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Thu. November 3, 2005
Replacing an old thermostat
Sometimes I have little revelations that pop into my head and recently one of these had to do with thermostats. Yeah, home ownership can really have an effect on you. Seriously though, I thought about the shoddy control over our natural gas furnace we have with our current, circa 1950s Honeywell round thermostat. It works well enough, I guess, except that it's analog and I'm just not into that sort of thing. I'm a digital boy. So, I did a little digging online and found that it's really no big deal (nor does it cost much) to replace it with a modern digital thermostat. With that, I hit the local Lowe's and picked up a new Honeywell (guess they've got quite the corner on the market) and began the installation.
Popping off the old thermostat wasn't any trouble but I did have to be careful because it has in it a vial of liquid mercury that, if broken, could cause some serious cancer. I gingerly set that aside and now had to figure out which wires went to where on the new thermostat. The new digital unit had spots for something like six or more wires but I read (and got a little pointer from Ken at work) that a simple gas furnace didn't need more than two wires. Great! Diligently reading the new unit's manual it informed me that the plate to which all the wires were connected on the old thermostat would have labels not unlike that of the proteins in DNA -- individual letters that may or may not have anything to do with the wire colors. This was not the case. I'm pretty sure our circular thermostat was pre-standards and, along with the mercury, probably had a plutonium core that would explode if jostled the wrong way. Nevertheless, no wire labels could be found.
I searched the Internets for old manuals and anything that might help. I found one place that alluded to where I should plug the old wires in the new thermostat but it was contrary to what I thought. There was one red and white striped wire that I thought should go in the "R" slot on the new one and the other in the "W" slot. Obeying my Internets overlord I tried it their way and it didn't work. Once I switched things around and turned the power to the furnace back on the warm glowing warming glow of hot air issued forth from our vents and life was good again.
Thanks for reading all this and, although boring, I hope someone searching the Internets out there will someday find this bit of advice useful -- I sure know I would've.
Comments (240) | To Top
11/16/2005 @ 3:15am
That wasn't boring at all. I don't think I've ever enjoyed reading about screwy thermostat installation before. Heh.
by Matthew Austin
11/25/2005 @ 2:30pm
Very interesting! did you go to the University of San Diego as a freshman?
by MaryEllen Pitard
11/28/2005 @ 6:47pm
I wish you had gone into a little more detail. I am having the same scenario you had.. replacing my old honeywell for a new one, except my old thermostat is the rectangle analog ones that I assume came after the round one you had. But just like yours there are no labels indicating what wire is what. I also have a red and white wire. I was searching the net for help and I came accross your page from a search I did on google. I also check the honeywell website hoping I would find a diagram of the old thermostat that would shed some light on this issue. Unfortunately, its seems that Honeywell does not believe in providing this kind of support on their website.
by Rigoberto
12/11/2005 @ 4:46pm
Wow, I'm replacing an old Honeywell with a new Honeywell,so you'd think the company wouldn't be so blithe in assuming that all wires or terminals will be marked in the back. My old Honeywell had nothing marked. Unfortunately, the wires in my house are so old too, so I don't see a red-striped wire. All I can say is that on the old face plate, one wire was at about where an 8 would be on a clock, and the other was close to where the 6 would be.
Thanks for this excellent post. If anyone has suggestions, please help. Thanks.
by Steve Filmanowicz
12/11/2005 @ 8:19pm
Steve: As I mentioned above, the "R" wire on mine was the red/white striped one that was near the 6 o'clock position (see http://www.kevinfreitas.net/journalPicView.php?date=2005-11-03&item=04) The other worked as the "W" wire.
Hope this helps. Cheers!
by KevinFreitas
12/13/2005 @ 4:07pm
So, what happened to the mercury switch? They can come in handy, but are really hard to find these days.
by Marshall
12/15/2005 @ 8:24am
I've got the exact same vintage Honeywell -- three of them, actually -- and with oil prices as high as they are I'm looking to replace them all for added efficiency. So hey, thanks for the helpful info!
by mattS
12/15/2005 @ 8:50am
mattS: Glad this helped. I was really surprised at how affordable new thermostats are. Seems more effecient since it's programmed to be pretty temperature conservative at night and while we're at work but, unfortunately, I can't compare it to a past winter since we only moved in last April.
by KevinFreitas
12/28/2005 @ 3:24pm
I'm in the same boat on the old thermostat with the discolored & unlabeled wires. If I can't determine which is the "R" and which one is the "W" wire, is there any harm in trying trial-and-error testing to find out which way works (can I harm the system by putting the wrong wire to the R and W connectors)? I figure if I try it one way and it doesn't work, I can try the other way .... but I don't want to break the furnace or new thermostat in the process.
by davo
12/30/2005 @ 9:47am
I'm replacing an 40 year-old White-Rodgers thermostat. There are three wires -- red, white, green. Any ideas how these correspond to the letter labeling system?
by dadzo
12/31/2005 @ 9:13am
Awsome....I followed your instructions and had no problem installing my Honeywell. You should write installation manuals for them.
by PJ Stalie
1/2/2006 @ 2:47pm
thanks! after finding un-labeled wires, i tried honeywell's site with no luck. then i stumbled onto your site and found my answers within a few minutes of reading and photo viewing. thanks for taking the time to share your experience, it made it simple for me to install my own thermostat. cheers!
by stofi
1/4/2006 @ 7:01pm
Same problem - the wires are unlableled on my old white-rodgers thermostat. I did a google and it brought up your page!
by jay
1/15/2006 @ 11:48am
Well since my house was built in 1904, and I have no idea when the furnace was put in (it still has the coal chute and coal room...) when trying to replace the honeywell round thermostat...I face a different problem. All the wires were brown...not red, not white...makes it hard to figure out which is which.
by Jeff
1/21/2006 @ 3:59pm
This site was an unbelieveable find. I not only had the same old thermostat with the same wire problem, I installed the same replacement thermostat. I can't imagine what compelled you to post both the solution and photos, but you really helped us out. Thanks.
Best-
Todd
by Todd
1/22/2006 @ 8:06pm
I had the same old honeywell with no letters, thanks to your info I was able to go ahead and wire and it works great.
by deity11
1/28/2006 @ 9:04am
Thank God for the Internets -- thanks for the great advice! I'm hoping this new thermostat will help me reduce my natural gas bills -- it's a tough year.
by Jason
1/28/2006 @ 9:14am
Todd, deity11, Jason: Glad my site helped. I certainly know I had a heck of a time finding info on replacing a really old Honeywell. Cheers!
by KevinFreitas
2/2/2006 @ 7:09pm
slick, worked like a charm!
by Johh
2/5/2006 @ 10:52am
I am replacing an old circular honeywell thermostat similar to your pictures on an oil-fired hotwater heating system. Besides the R & W wires a third unused wire was there. Would this be a C or G wire?
thanks
Andrew
by Sir Not-Appearing-In-This-Flim
3/11/2006 @ 2:12pm
I have an old white rodgers thermostat and it is not labeled either. It has three wires, two of which are connected to the sealed mercury vial. one is white, one is yellow and one is blue. help!
by Denise
3/26/2006 @ 3:55pm
You, Sir, are a God!!! I had the exact same antique Honeywell thermostat, and would have been lost in upgrading to a newer one had it not been for you (and especially the pics which mirrored my situation exactly). Not to mention being unaware of the mercury in the old unit, which I would have flung into the garbage. Any idea how to properly dispose of such a hazard (probably will consult with my friendly city sanitation department unless I hear of any other thoughts)? Again, thanks again!!
by ejmuelle
5/14/2006 @ 8:39am
My replacement situation is like Rigoberto's, except that I have yet to figure out how to get the old one off the wall after removing the cover. Help?
by Mary W
5/14/2006 @ 9:53am
We managed to replace the white-rogers thermostat with a honeywell RTH7400 for our heat pump (2-stage cooling, 2-stage heating). We have the following wires: W2, R, O, Y, G, and an X1 which we attached to the C terminal. When we tell it to cool the house, it heats; when we tell it to heat the house, it also heats. Please tell me how to fix this? Thanks!
by Mary W
7/2/2006 @ 11:36am
Hi,
I don't know if my last email worked so I am trying again. I just changed my old honeywell mercury thermostat with an electronic one, heating and cooling options 4 wires, non of which were color coded.
Mary try swapping your Y and W wires try website giveme5.honeywell.com/Product/digital%20round/T8775%20Product%20Data%20Sheet.pdf
it is in the honeywell website. also try hammerzone.com/archives/hvac/controls/tstat1/replace.htm it was also useful for me. I am guessing W2 goes to your heating relay.
hope this helps
by Darren
7/7/2006 @ 10:08pm
I am trying to replace a white rogers t-stat for 2 stage heat 1 stage cool with the following conections
R-red
G-greed
Y-yellow
B-orange
W2-white
X1-blue
I am trying to replace it with a hunter set and save model 44360 with the following connections
RH- 24 volt
RC- 24 volt cool
G- Fan
Y/O- air conditioning compressor
W/B- heating or reverse valve operation in heat mode.
Y1- heat pump compressor
what wires shoulod connect to what onthe new tstat?
help please
by mark w
7/16/2006 @ 5:06pm
I am so glad to know I'm not the only one in this boat!! I too have a house built in 1904. And of course, the wires on the old round Honeywell are also brown...and unlabeled!!!!!! Gah! I am going to give a try, hoping I don't turn it back on and cause my house to implode like the Poltergeist house.
by G
8/7/2006 @ 12:39pm
I'm replacing a older honeywell programable theromstat with one that has the off switch plus the fan.
There are only 2 wires coming in red and white plus there is a humidifier wired next to it.
There was a jumper wire black and white connect to the red and white screws.
Are they suppose to be connected .
There is no a/c.
I want to be able to turn on the fan.
the letters on the thermostat reads
o w g c r rc
How do I wire this?
Thanks
Willy
by Will
8/8/2006 @ 1:30pm
thanks so much for providing some help here-I get home from after after the Honeywell customer service leaves every day, and their website really is no help. I like you have 2 wires, but 1 is black and 1 is white. The old unit I am replacing looks exactly like yours, with no labels anywhere, and the new one is the same one you have also! Thanks so much for the tips!
by Christina
8/9/2006 @ 4:54pm
Well, that does nothing to help me. I have an old line voltage thermostat. It runs a fan unit on a radiated heat/cool system. I'm in an old building where the radiators pump a super cool liquid during summer and in winter a heated liquid runs through them. But I cant find a newer thermostat that will run line voltage for both heating and cooling.
by Patrick
9/3/2006 @ 6:51am
Okay,
I gave up at midnight and its' HOT in Katrina Land.
This is how the old round Honeywell T87F is labled and what color wires(4) are attached:
B = green wire
O = no wire
R = Red
R = no wire, next to the above R
W = black (I think; wire came off during remoal)
New Honeywell RTH110B is a digital/non-programable.
I think I might try:
Rh = red wire
Rc = skip (jumper wire between Rh & Rc)
W = black wire
Y = white/yellow wire
G = green wire
Y = White or yellow
Will I ruin the unit if I try and it is wrong?
Getting Hotter! HELP!
Kathy
by Kathy
9/8/2006 @ 4:17pm
Hi there, just wanted to say thanks for this information. I have had a new thermostat for 2 years now and hubby has delayed putting it in. He finally got around to taking the old one off as we painted in the hallway. Once off he ran into the same problems as everyone else. Two wires with no markings. I google and found your site. Thanks a lot for taking the time to write this or I might have been another two years waiting for heat.
by Barbara Jackson
9/15/2006 @ 11:55am
FWIW, I have a black wire and a white wire on a house made in 1961. First I put the black one on "C" and the white on "W", but that did not work. After I found your blog, I put black wire "R" and white on "W"; that seems to work.
Thanks, Kevin.
by kickstand
9/21/2006 @ 2:34pm
AAAGH!! A simple 30 min job is turning into a major headache! Go to change a old Honeywell thermo ( with clock circa late 1950's early60's?), and suprise - 3 wires, white, red and Black plus 2 wires from electrical tansformer to power clock. Tried wiring as per 2 wire system - no go! Where does the black wire go?
by Emma K-W
10/10/2006 @ 2:16pm
Same situation. 2 wires--one blue, the other white, no labels. Old Honeywell slide thermostat. With your information about the R and W slots, in addition to other people's postings, I was able to figure it out. Worked like a charm! Thanks for providing this info.
by Marcus
10/14/2006 @ 2:28pm
Thank you so much, you made my day!!
R at 6
W at 8
by Ben
10/15/2006 @ 5:44am
Just wanted to point out that the magic R at 6 and W at 8 works for an oil fired furnace with no central AC as well. If you have extra wires, they're probably for a fan, so run with that. Thank goodness for this website! I couldn't believe it when I read all this and took a look at my old thermostat and there it was, a shiny vile of mercury. Incredible.
by Susan
10/15/2006 @ 9:25am
Yikes!! I have the same prob. Took off my old honeywell thermostat to my gas furnace,( A vertical one),replaced it with a hunter and have 2 wires. Black and white. I hooked the white to the "W" and the black? I HAVE to use that one don't I? I wired it to the "RH" spot. Hope it works. Anyone know better than me??
by Seyi
10/15/2006 @ 7:11pm
Thanks to your page I was able to successfully replace my old Honeywell with a new digital thermostat. I feel like such a handywoman! Thanks so much!!
by Angie
10/15/2006 @ 9:47pm
Installing a new White-Rodgers t-stat-4 wires,red,white,yellow and green,what terminals do they go to?
by James Honeycutt
10/22/2006 @ 11:09am
I attempted to change my old Honeywell electric clock thermostat for a new fangled programable one and thanks to your site I had the confidence to do it. I feel so good having done it. Thanks to your site.
by Lois
10/22/2006 @ 6:42pm
Thanks for the info!! Another alternative is to look on your furnace and look at the wiring there. For me, it was easy to find and well diagrammed.
by Chrissy
10/24/2006 @ 2:27pm
Without your directions I would still be waiting for Honeywell to respond. Work Great Thanks
by Dennis
10/29/2006 @ 2:07pm
THANK YOU, THANK YOU, THANK YOU for posting the info. We have a very old round mechanical Honeywell thermostat with two wires: 1-red (at 8) & 1-white (at 6). Left to my own devices, I would have installed the wires in the new one backwards. Luckily for us, we found your blog and followed your advice. The new thermostat works!
Shame on Honeywell for assuming everything is well labled on old thermostats!
by Carol
10/30/2006 @ 5:41am
You wrote" There was one red and white striped wire that I thought should go in the "R" slot on the new one and the other in the "W" slot. Obeying my Internets overlord I tried it their way and it didn't work. Once I switched things around..."
How did you switch it around? Do you go with your initial thinking (red/white into R, white inot white), or what?
Thanks for this post, seems several have found it helpful.
by Jeff
10/30/2006 @ 6:16am
Yup, I went with my initial red/white into R and that's the one that worked.
by KevinFreitas
10/30/2006 @ 7:41pm
You are a Godsend!!! Every place else I looked was just pointless, especially Honeywell, their troubleshooting wizards were more like troubleshooting jesters. I followed your suggestions and it worked!!! Thanks for saving me from being the laughing stock of my household!!!!
by Mia
11/4/2006 @ 8:43am
Great directions. I had the same setup in my house and found your directions to be really good. I actually called Honeywell, just to confirm all of this. They told me that in wiring setups with just two wires (w and r) there's no need to label them. So long as one wire goes to a W and the other to a R, the system will work.
by TEd
11/5/2006 @ 4:49pm
Thank you for this informative post!
You saved me a lot of time. I had exactly the same old style mercury thermostat and the same new digital one to go in its place. Honeywell's website is no help, and the manual doesn't even indicate which terminals do what. I knew I needed to short the wires to turn the heat on and disconnect them to turn it off. Had Honeywell said these two terminals (R and W) provide the contact closure for heat, it would be so much easier to figure out the correct wiring. But no, they don't want us to think, just follow instructions. When you use their so-called Wizard, and indicate that the wires are unmarked, you get a form to fill out to be contacted by them.
Thank God for helpful folks like you!
I hope Google has you near the top every time someone searches for "Honeywell 7400 wiring"
by Jan L.
11/8/2006 @ 8:00pm
THANKS!. You saved me a bunch of time. Worked the first time.
by canoetrpr
11/11/2006 @ 3:44pm
I am replacing a White Rogers Thermostat IF58W-77 This is for a heat pump 2 stage heat and 1 stage cool. I purchased a Honeywell 7400 series but it wouldnt work. Heat would be on when cooling was called for Old thermostat has connections R, G, X1, E, O, W2, and Y Technical support didnt help from honeywell
by Benny
11/14/2006 @ 7:29pm
Can't say how much comfort it is to know I'm not really stupid! I can't believe, that for a company as large as Honeywell, their website is not user-friendly, and frankly, not helpful at all. Thanks for your info regarding the thermostat. Knowledge learned should be knowledge shared. Thanks again!
by Marisol
11/17/2006 @ 11:08am
ok,heres the deal,,,,,,,i took the old honeywell unit off the wall(mercury type) and the wires FELL out.Some in this batch are folded so i got on the roof and traced them to the heat/cool ac unit..,,Ive a red,white,blue,green and yellow bared,,,where do i put them on my new honeywell7400 unit please....?
by al
11/19/2006 @ 5:16pm
It's about a year since your post and still, what a life saver! I didn't find much except for this post and I'm so glaaaaad I did! Now, if I could just find more info on messing with knob and tube wiring!!
Thanks a million!
by Margaret
11/20/2006 @ 8:28pm
help very cold replace arectangel white roger mercury with honeywell rth3100c e aux y g o l r b c i have black white yellow green oranre red blue and no more info ....it runs but on heat thanks for any help i dont have the old thermostat any more. dont know what to do....
by bonita
11/21/2006 @ 7:42am
Hi, I installed a new thermostat, Colors were as follows, Black going to the green label, organge going to the Yellow, red going to redh and redc yellow going to white, i did the same thing in the new one, but nothing works but the fan when it's on ON, no heat no auto, can you please help.
by moe
11/24/2006 @ 9:30am
HI,
I'm changing an old White-Rodgers mercury t-stat and have 2 wires, a black and a white. The white appears to be the ground at the r lower corner, and the black seems to be the live wire. How to I connect these to a new programmable tstat? (NOMA)
by Patrick
11/27/2006 @ 9:30pm
It said it only takes 15 minutes on the package, but I am on day two of trying to figure this out! I'm replacing a White-Rodgers mercury analog thermostat with a digital Honeywell one. I have a black and white wire. There was also a red one connected to nothing on the old one, so I don't think that one is critical. The black one was connected to a terminal marked Y, but I don't know if I trust that since I have read Y is for cooling and I am trying to get the heating to work. Where do I hook up the balck and white wires?
by Krista
11/29/2006 @ 10:22am
Ok i worked it out.The red wire bridges to r/rc. The white whire goes to W and yellow goes to Y but they are Bridged. Blue isnt used and Green goes to G. I have heat again and the fan works in auto as it should. I hope this helps ,now the house is toasty :)
by al
12/3/2006 @ 9:48am
I filled out the wiring wizard on the Honeywell website at http://yourhome.honeywell.com/Consumer/Cultures/en-US/Support/Thermostat+Wizard/
Honeywell emailed me back in a day or two and said to use R and W, and it didn't matter what order. Leave the installed jumper between R and Rc.
So I hooked up black to R and white to W and it works great!
by Krista
12/21/2006 @ 11:17pm
So simple and thanks so much. I love the Honeywell controller but they could do a much better on support at their site.
For my simple Taco zone valve it was red to R and white to W. The instructions tell you to ignore the current color coding.
I believe connecting the white to W and whatever other color to R will work. I am now off to purchase some more of these controllers for my house and garage.
Thanks a million!!!
by Andre
12/24/2006 @ 11:23pm
okay.......i've frickin had it with the honeywell website. they don't tell you jack crap about anything. i'm trying to replace old thermostat, jade controls, with a new honeywell rth6300b. I have a red, blue, yellow, and green wires. red connects to r, blue to o, yellow to y and w, and green to g. so i get the red is going to connect to r with a jumper to rc, yellow to y, green to g, which leave me with the blue to w (or o/b). is this a good guess or not? also is there not going to be a jumper wire then from the y to the w like on my old thermostat? Someone please help me before i end up having to check myself to a place that has padded rooms just from trying to put in a new thermostat!!!!
by Gina
12/30/2006 @ 4:59am
I stumbled on this page in my search for info on replacing old mercury thermostats w/ digital thermostats. Very helpful. Thanks!
by Ray
12/31/2006 @ 12:54pm
Thanks- I also had just a black and a white wire on my old round mercury Honeywell. Black to R, white to W. Honeywell should get off their high horse and read these posts. There are thousands of these old style thermostats out there and they are not making it easy to replace with the new efficient models.
by John
1/2/2007 @ 9:53am
We have an ancient Honeywire analog thermometer with no labels. Can someone please tell us what color wire correspond to what? We have: Red, Black, White and Blue. Thanks in advance!
by Jamie
1/2/2007 @ 5:36pm
I have a gas boiler, no AC. The wires coming out from wall are green, white and red. I have Noma progammable 5+2 thermostat with the following terminals: W,Y,G,RH,RC,O,B,H1 and H2. How do I wire this for programming heat only? Thanks for the help..
by Ted
1/2/2007 @ 6:29pm
Sorry, correction on previous message. The color is not green, but blue, if that makes a difference. Thanks.
by Ted
1/5/2007 @ 3:30pm
is it ok to replace an old one with a new one
by Jay
1/21/2007 @ 11:30pm
Thanks for this site... and thanks to those of you who confirmed with Honeywell that R & W are interchangeable. My wires were identical and I was glad to confirm the order didn't matter. I'm all set up!
by Glenn
1/28/2007 @ 8:30pm
I am looking to replace a very old rectangular honeywell thermostat, when I attempted to take the old one off--it did have the mercury vial in it. It has more like a coil. Not what I was expecting-Can anyone tell me if I can proceed with normal installation
by michelle
1/28/2007 @ 8:31pm
correction-IT DID NOT HAVE A MERCURY VIAL IN IT!!!
by michelle
1/29/2007 @ 6:04am
great info. I had one blue and one green wire on an oil furnace with very old round honeywell thermostat. Very happy to know i can switch them interchangeably between R and W positions and that i need to keep the relay between Rh and Rc. Thx!
by AG
1/30/2007 @ 9:00am
Thanks for the tips. Thermostat at our place seems to be stuck in two settings: medium and boiling. Off is no longer an option.
Ours does have the mercury. How does one dispose of this?
by Bill Dineley
1/30/2007 @ 9:35am
Bill: Your local waste management should know what to do if you give them a call.
by KevinFreitas
2/3/2007 @ 12:41pm
Hi, Just a quick and simple explanation of why it doesn't matter for two-wire systems on which wire goes to which terminal, (i.e. "R" or "W"). This is a low-voltage 24V ALTERNATING CURRENT circuit, which means the current in each wire alternates between + and - (at 60Hz I believe) so they are for all intents and purposes IDENTICAL. Put either to either terminal and it should work. Hope that clears things up.
by David
2/5/2007 @ 6:15am
i installed new nome auto thermostat but fan comes on same time as the burner assume wire is crossed can you help ?
by p merrett
2/7/2007 @ 12:01pm
Hi Ken,
How often do you have to replace the batteries in the new RTH110B Thermostat. I'm trying to find one that will run an empire direct vent 750 millivolt heater, and have been told that the RTH1110B will work, but that the older round TS86A model that has no batteries will also work.
Thanks,
glenn
by glenn
2/12/2007 @ 10:30pm
Thanks for your site!! I'm about to open and install a RTH7400 to replace an antique, mercury based, 2 wire, 24volt, gravity hotwater heat only, T. stat.
I will be relocating the new T. stat (the old one is in the kitchen!!!) I'll pull new, 3+ conductor wire. So,... should I give the new T. stat constant 24Vac? (Not just leakage through the existing gas valve coil.) Anyone know where the 24Vac supply wire would go? I know the two existing wires that switch the Nat gas conversion burner on/off go to R & W.
by Happy I found you :-)
2/13/2007 @ 6:25pm
Never mind. I see the stat gets enough power over the existing two wires.
by Happy I found you :-) (again)
2/14/2007 @ 5:48pm
Another satisfied customer. Thank you for your posts, and help - at this late hour at 5 degrees outside, while my new Honeywell is waiting to be connected. R & W, here I come.
by John
2/24/2007 @ 12:40pm
Thank you everyone! With the information found here, I was able to (almost) effortlessly replace the ancient 2-wire thermostat with a Honeywell programmable unit. It works perfectly!
by Paul (CGCampers)
2/27/2007 @ 11:56am
Now, I got mine working but I did one thing that is now keeping me wondering. I was not able to fit my cables into the R terminal without removing the "Jumper or Bridge". The system is working fine on my too zones. Since I do not have cooling (not that hot here in Canada), I should be OK, right? Thanks in advance.
by Rick
2/28/2007 @ 4:52pm
Just adding my thanks. R at 6, W at 8 worked for me. It's somewhat unbelievable to me that I couldn't find such helpful info anywhere on the Honeywell site. But thanks to you (and Google!), I got the info I needed and got the thing working fine.
by Sir Not-Appearing-In-This-Flim
3/2/2007 @ 6:50pm
It's great that people like you take the time to put stuff like this on the internet. I had the same no label wiring problem. This site was exactly what I needed.
by Curt
3/3/2007 @ 1:58pm
Room temp displayed follows set point selected without change in actual room temperature!
(Heat only, Gas, hot water, gravity, huge radiators ie/ slow to change, Smart response selected)
Adjacent digital thermometer displays 21.5 & room feels cool
Set point at 72 F room temp display 72
Push “up” button once. Heat comes on
Temporary set to 73 displayed
Within ~3 min room temp display changes to 73
Push “up” button again. Heat remains on
Temporary set to 74 displayed
Within ~ 3 min room temp display changes to 74
Push “down” button. Heat remains on
Temporary set to 73 displayed
Within ~3 min room temp display changes to 73
During all of the above the adjacent digital thermometer displayed an unchanging 71.5 And elapsed time was only ~9 minutes.
by Normal RTH7400 behavior?
3/4/2007 @ 12:29pm
was wanting to know, if i have a old round thermostat, and replace it with a digital, and i have central air and gas heat will it still work and i dont know how many wires i have yet in the wall
by Scott
3/4/2007 @ 1:27pm
Thank you for this great information. I opened up the thermostat and it was easy to hook up. This was a great resource for a stupid problem!
by LeeLa Heinzel
3/4/2007 @ 4:08pm
Thanks! This worked great. I was just able to discern the reddish color of the old insulation on one wire and the (dirty) white color on the other. I installed our brand-new Lux thermostat and it's working like a charm.
by Dave
3/8/2007 @ 3:06pm
what is the jumper on the back of the thermostat used for?
by dale
3/10/2007 @ 6:59pm
whew! until i found your site i was beyond stressed. switching from the round mercury thermo to a digital one ...the directions were useless! thanks again!
by Friend of Fiver
3/11/2007 @ 11:54am
I bought a hunter thermostat and my thermostat has an "E" wire, but the hunter doesn't what should I do?
by Jason
3/18/2007 @ 8:01pm
replcing a lennox thermostat with diagram,
G-green
O-orange
RH & RC- red, same wire spliced
W-white
Y-yellow
with
Honeywell thermostat T8411R model
G
C
R
W1
O
What goes where?
by dcsecseo
3/24/2007 @ 10:15am
We had two black wires and guessed. It works so far. Thanks!
by Mike
3/31/2007 @ 8:04am
mIKE, AT LEAST YOUR MORE HELPFULL THAN HONEYWELL TECH SUPPORT. I HAVE THE HONEYWELL 7400 SWITHING OUT A HUNTER 44428. I HAVE A BLACK WIRE THAT WENT TO "A" ON THE HUNTER BUT NO "A" ON THE HUNEYWELL. THE O/B ON THE HUNTER HAS THE ORANGE WIRE GOING TO IT. ANY IDEA?
TKS
BOB
by ROBERT FROST
4/4/2007 @ 8:37am
Help we took off a white rogers prog. 2 stage 3 zone thermostat and not sure if the wiring is accurate. We can't get heat from any zone. Seems the thermostats are in communion with one another. It is F1-80. Thanks.
by Sir Not-Appearing-In-This-Flim
4/19/2007 @ 6:40pm
HERE IT GOES
E IS FOR ELECTRIC HEAT.
W1 IS FOR A HEAT STRIP OF SECOND STAGE HEAT.
RED WIRE IS THE POWER WIRE
WHITE IS YOUR HEAT WIRE
ORANGE IS FOR A HEAT PUMP REVERSING VALVE
YELLOW IS USED TO TURN ON THE COOLING CYCLE
GREEN IS THE FAN WIRE, COULD BE BLUE.
IF THERE IS A GREEN WIRE, THEN THE BLUE WIRE IS THE COMMON WHICH IS NEEDED IF YOUR T-STAT HAS A CLOCK.
THE JUMPER IS USED ON SOME T-STAT BETWEEN RC AND RH TO POWER BOTH THE HEATING AND COOLING. IF YOU HAVE BOTH, YOU WILL NEED THE JUMPER. IF YOU DO NOT PUT IN THE JUMPER THEN YOU WILL NEED TO MOVE THE RED WIRE BACK AND FORTH WHEN YOU NEED HEAT OR COOLING.
IF THERE ARE ONLY TWO WIRES AND THE UNIT IS A 24 VOLT TYPE, IT SHOULD NOT MATTER WHICH WIRE GOES WHERE. iF YOU PUT THE TWO WIRES TOGETHER THE HEATER WILL COME ON, AND RUN FOREVER, OR UNIT THE UNIT MELTS DOWN. IF YOU WERE TO PUT THE RED, GREEN AND YELLOW TOGETHER, THE COOLING CYCLE SHOULD START. RED AND WHITE SHOULD START THE HEATING CYCLE.
T-STAT ARE DESIGNED DIFFERENTLY DEPENDING ON THE TYPE OF SYSTEM YOU HAVE.
WALL HEATERS ONLY HAVE TWO WIRES, AND WILL NOT WORK WITH A 24 VOLT T-STAT. YOU WILL NEED A MIL-A-VOLT T-STAT.
by WALT
4/28/2007 @ 1:24pm
Thank you for this guide, i am in the first year of first time home ownership, and this was a great help.
by Cliffy
5/1/2007 @ 7:11pm
Thanks. we replaced our old round Honeywell with a new Honeywell programmable rth8500
black wire @ 6 to R
white wire @ 8 to W
Brilliant! It worked the first time! Cheers!
by Phil and Kate
5/4/2007 @ 6:20pm
i am replacing an old thermostat with a honeywell and the i have a wire that was labeled as a T and the only letter i didnt use on my new one is a L.. is this it.
thanks
by manuel
5/4/2007 @ 6:25pm
The model number is RTH3100C and
by manuel
5/6/2007 @ 4:36pm
i am trying to install Hunter 44760 and going from a Lennox 8743 (I believe). This is a 2 stage heat pump and cooling. The Lennox is wired Blue - V,Yellow - X, Black - R, Orange - Y, Brown - L, Green - F, Red - M, White - A, and nothing is connected to the E terminal. I can't find any diagram for the wiring for the Hunter 44760. Can you help?
by Bob
5/18/2007 @ 2:17pm
I started looking for help to do this project once I gathered enough information. After reading all of this, I may simply get an electrician to do it, then SHOOT him! I know its all one big plot for sure now! Not that I'm paranoid mind you~ ;-)
by Carl
5/18/2007 @ 2:22pm
Ok, I start off with a thermocouple that will not ignite from the pilot flame. I dare not attempt this one because the internet said not to. Yeah or nay?? While searching for help on this I ran across upgrading the thermostat itself...seems logical, right? Forget it! Know a good electrician in Kingstowne, Virginia?
by Carl
5/18/2007 @ 2:24pm
ok, where's Kevin when ya need him????
by Carl
5/18/2007 @ 2:28pm
Hey Carl -- sorry I'm not an electrician nor anywhere near the Commonwealth. ;) I'm just a guy, like many here, who needed help and couldn't find it anywhere else. Good luck with your project and hopefully other folks with chime in here with helpful tips.
by KevinFreitas
5/20/2007 @ 5:20pm
I recently replaced my old thermostat with a Honeywell RTH110B. I started having episodes of my fan coming on in the cooling mode but not the compressor. This snowflake that keeps showing up on the display has me snowed. Any suggestions? I feel dumber than a fifth grader.
by Ken
5/21/2007 @ 3:51pm
Hey, I appreciate the effort you make to help others! And free too! lol
by Carl
5/28/2007 @ 4:31pm
OMG....I'm it's too hot to have a CRAPPY landlord lol. Can some1 PLZZZZZZ tell me what color wires goes to what on the thermostat. It's a hunter model # 44155C. My wires are red, orange, yellow, blue, green, white, black and brown. the thermostat in order is G...RC..RH..Y/O...W/B..Y1
by HOT AS u know what!!!
6/25/2007 @ 12:49pm
I HAVE NO LABELED WIRES ON MY OLD THERMOSTAT, THE COLORS COMING OUT OF MY WALL ARE GREEN, RED, WHITE AND BLUE. I HAVE BOUGHT A NEW LUX TX 500. THE DIAGRAM ON THE NEW ONE HAS A PLACE FOR GREEN, YELLOW, WHITE, RH AND RC. CAN YOU HELP ME DETERMINE HOW TO HOOK UP THE WIRES.
by JULIE
6/28/2007 @ 12:02pm
Yesterday while moving in a refridgeator I severd the old thermostat off wall hardware store sold my friend a honeywell RTH110B the only problem is that the wires were only hanging 2 in one jacket red & white and 3 red,white ,green in second jacket New Honeywell RTH110B is a digital/non-programable.
Rh = red wire heat
Rc = red wire cool
W = ? wire
Y = ? wire
G = green wire
I just don't know I crossed the fan& condensor wires but friend called at 3 am to say it was 63 degrees had to tell him to pull breakers. honeywell site no help someone please help.......
by steve redman
6/28/2007 @ 4:18pm
I have a 1957 round Honeywell thermostat with a new 1985 Lennox thermostat. The 1957 Honeywell had a small night light built into the thermostat. The Honeywell had 5 wires: red, white, blue, brown, and yellow. The Lennox thermostat only has 4 connections red, white, green, and yellow. I taped the brown wire up and connected the blue wire to the green connector on the Lennox thermostat and it works ok. Was the brown wire for the night light?
by Jordan
6/28/2007 @ 4:24pm
I should of said that I replaced the 1957 round Honeywell Thermostat with a newer thermostat (a 1985 Lennox Thermostat) which was given to me. The older 1957 thermostat was not working right ( the air-conditioner would not turn off yet the heat worked ok.
by Jordan
8/8/2007 @ 6:21pm
My house was built in 2006, yet I only had 2 unlabeled wires coming from the outdated thermostat (one red and one white wire). I wanted to upgrade to the honeywell 5-2 programmable thermostat. On the old thermostat the white wire was at the 6 oclock position and the red whire was at the 8 oclock position. I put the red wire in the W slot and the white wire in the R slot (after removing the metal pin) and it worked like a charm!
by Sixx
8/16/2007 @ 7:50pm
kevin-
did you remove the jumper between R and RC on your new digital T-Stat? i see some people post that they did and some did not.
by will
8/26/2007 @ 4:25pm
I am trying to replace my really old Honeywell thermostat, model T666A. I couldn't find any information on the internet. The wiring terminals are number coded, from 1 to 4. The cover has a small diagram showing the diagram of the wire. It seems like 1 and 2 are for heating and cooling. But I am having hard time to figure out which one of 3 and 4 are fan relay and heat/cool. Any idea where I can find the manual or cross-reference chart showing which wire is which?
by rachel
8/27/2007 @ 5:43pm
Help! I'm roasting- no, freezing- no, boiling... welcome to Minnesota! I'm trying to replace a Honeywell T87F ( the "old round one") with a Hunter 44155C. Unfortunately, I now just have a jumble of wires hanging out of my wall.
The old system:
W-R-B-G-Y
The new system:
G- R/C - R/H - Y/O - W/B - Y1
After hours of consulting both owners manuals, my furnace, 10 internet sites, the Thermostat Wizard (ha ha ha), I threw up my hands.
by Jan
10/10/2007 @ 8:27pm
This is the most useful information we were able to find on the internet regarding our circa 1950's Honeywell round thermostat w/ the mercury vial and 2 wires (1 white at 8 o'clock and 1 red at 6 o'clock). I guess it doesn't matter which way we hook them up so long as the jumper is left between R and RC so--we're on the way to hooking up our new Honeywell 5-2 Programmable Thermostat on our oil-fired heating system now. Thanks for posting this much-useful information!!
by Alishia
10/11/2007 @ 4:05pm
Im trying to trade out from a Honeywell T8411R to a Hunter42995B. I have 7 wires coming out of my wall Green,White Yellow,Red,Blue,Black and Orange. On the Hunter it says,Rh,Rc,G,Y,W . How would i wire this?
by Lesa
10/13/2007 @ 1:12pm
I had an o-l-d 2-wire Homart/Sears thermostat on the wall. I'm very thankful I found your page here =)
Hooked the new Honeywell up per your example, and everything is roses.
Much appreciated =)
by Nettle
10/17/2007 @ 4:14pm
I replaced the analog thermostat in an uninsulated Buffalo apartment. Months later, the digital thermostat failed in the middle of the night, and we woke up when the temperature in the apartment fell below 40.
by buffalo2wheeler
10/19/2007 @ 10:06am
great post. this is by far the best, simple to read and most detailed piece of internets information out there. Personally I have a wall gas heater with some Columbia Electric older millivolt thermostat with two unlabeled wires (both just black!) and by luckily finding a dated Honeywell manual, I discovered that, according to this manual for a two wire system it doesn't matter which order (so they claim), but they should connect, as kevin writes, to R and W.
by jon
10/19/2007 @ 1:58pm
Thanks Kevin, your info is still helping others. I too installed a new Honeywell digital thermostat today and was stuck when the old unit had no letters labeling the wires. I had a blue and white 2 wire harness.Using your pics and the 6 and 8 o'clock position mentioned, I hooked the white wire to R and the blue wire to W and it works like magic. Thanks for sharing your info
by Bruce
10/21/2007 @ 2:07pm
we spent all afternoon trying to figure this question out (the red and white wires). your info was exactly what we needed and salvaged our home repair efforts. now it's a succesfull afternoon instead of a frustrating failure!! thanks so much.
by Jill and Mike
10/26/2007 @ 12:34pm
Great page. I too have an old style thermostat but with 5 wires connected. The old thermostat had labels (G,W,Y,4,R,A) - heating and central air.
These new thermostats are simply switches. For an RTH6300B, I used a multimeter to determine each switch condition:
Pressing Fan button to ON connects G-Rc
Cooling ON connects G-Rc and Y-Rc
Heating ON connects W-R
For my furnance and central air, a separate 24Vac transformer is used, so I needed to remove the jumper between R and Rh.
by Mike
10/26/2007 @ 12:36pm
Correcton to above: I mean R and Rc, not Rh.
by Mike
10/27/2007 @ 10:08pm
well i have an old honeywell thermostat I want to replace with a honeywell T8601D. I know my old thermostat is just a 2 wire system. A red and white wire is what it has. You connect them together the heater starts up and you seperate them and heater stops. real simple setup. Well I tried hooking them up to the W and R but it did not work for me. When i hook up to these ports it does power up the thermostat but does not start furnace. I adjusted the temp i wanted to see if it would activate the furnace but it didnt. I did by this thermostat from eBay so i do not know its history. One thing in the back of my mind is there suppose to be any jumpers besides just the two wires hooked up. Any suggestions in how to hook up the new thermostat...thanks for any assistance
by FRANK
10/29/2007 @ 6:51am
To Frank:
You probably need to configure the T8601D for the type of system you have.
You can download the manual here:
www.ventingdirect.com/pdfs/Honeywellguides/69-1410.pdf
by Mike
10/30/2007 @ 1:52pm
i went thru the manual in the beginning and didnt make any sense too me. I called Honeywell and it was a waste of time. They told me to hook up to the R and W and when it didnt power on they said call a contractor to wire it up. It will cost me more for the contractor than what the thermostat did...not a good use of money for a 2 wire simple system
by FRANK
10/31/2007 @ 10:10am
It seems that your thermostat needs a power connection to terminal C. My RTH6300B runs on batteries.
If you look at page 2 of the manual in Figure 3, you'll see that C needs to be connected also. Connect Red to R and white to W. Then connect a wire from W to C.
by Mike
10/31/2007 @ 3:51pm
I'm attempting to replace an old GE Weathertron with a Honeywell RTH230B. The Weathertron has 8 (yes, 8) wires coming into it. The Honeywell has only 5 terminals. I may just need to spend more money on a replacement thermostat. It's just a condo, and I don't feel like putting a lot of money into it. Here's the list of 8 wires:
R
T
O
G
Y
X2
B
W
The replacement has Rh, Rc, W, Y, and G. Any suggestions.
by Joel
11/1/2007 @ 9:16pm
mike, didnt work..i did a jumper and it powers on the thermostat but when it goes to kick on the heater you hear a click and all goes blank on the screen. a second later the display comes back on like it was reset. what I am wondering is where else can i get a constant 24v for the unit
by FRANK
11/2/2007 @ 10:29am
Frank: The click you here is the relay switch closing W to R, but I assume when it does that power is no longer routed to the thermostat and with the no power, the relay opens (i.e. a normally-opened relay) disconnecting W to R.
Did you try a wire across R to C ?
by Mike
11/3/2007 @ 9:38am
Hi
This was incredibly helpful and re-assuring. I agree with the others, shame on Honeywell and Thanks to you!
John
by John
11/3/2007 @ 11:54am
I wanted to add my thanks - my old Honeywell was installed in 1937, and neither wire was colored (both wrapped in brown string, it looked like). The pictures were very helpful, as were a lot of the other comments, and the descriptions of the wires being at 6 and 8 o'clock - otherwise I would have been out of luck!
For those of you with two-wire systems who are connecting but not working, make sure that the wires are well seated and tight into your new thermostat. My wires were old, very thick copper, and they did not want to stay where I put them in the new unit without a lot of straightening and fidgeting. Good luck!
by Megan
11/4/2007 @ 5:15am
please advise how to replace old honeywell electric clock on left side thermostat with a new one. the heat will not go on the gas burner is new and work ok
by rivkah
11/4/2007 @ 6:13pm
thank you! if only i had found your website sooner! after much debate (i have the same round mercury filled honeywell with no labels but have a black and white twisted wire and a white wire) i decided that the two necessary connections should be r and w. but we needed new wiring, so we replaced it, hooked it up and had to do the same switch you did. all is good now, but i wish this was a bit more commonly known. thanks anyway.
by felice
11/6/2007 @ 6:15am
replacing old stat with wiring as follows:
red to r
white to w
green to g
blue to y
and a jumper from y to 1
I assume red will now go to rh on the new honeywell.
white to w
green to g
and blue to y
this doesn't seem to work. if i add the jumper from y to rh, rc i get constant fan power, but no fan without it.
help!
by todd
11/9/2007 @ 1:44pm
Thank you , Thank you, Thank you I did a websearch to connect a Honeywell RTH 211B PURCHASED AT Home Depot. would you believe it was manufactored July 2007, and if you go into the Honeywell site on the thermostat wizard "no referance is made". Now how is that for product support! I had the two black wires coming from the old rotary dial mercury switch in essence a continuity switch. No labeling on the old thermostat and No referance on the New Thermostat documentation to which the wires should go, Great product support!
In short just wire each lead one to the " W" and one to the "Rh or Rc" since it already comes bridged it does not matter which and as the French would say " whala"!
by Edward
11/12/2007 @ 12:31pm
I want to replace my old Honeywell round, manual thermostat, Model T87F with a new Honeywell digital, non-programable one, Model RTH5100B. I have some questions.
1. How do I get the old one off the wall? I see five screws. Two with what looks like tan or white wires attached. The other three have nothing.
2. Are the two wires I mentioned above the two that I attach to the new thermostat or are they behind the thermostat on the wall? I pretty sure that I only have to deal with two wires. My furnace has no fan or an a/c unit.
Thank you.
by Nick
11/16/2007 @ 2:00pm
Hello,
I need help. I have an old Coleman Presidential III with heat and air. It has the original thermostat installed that only has two wires - a red and a white.
I bought a new digital thermostat to replace the old ugly one. It is a Honeywell RTH110B.
I connected the red wire to the Rh and Rc with a jumper and the white wire to the W. Now, the heat works right. It will come on and go off depending on where I set the stat. The cooling however will stay on constantly no matter where I set the stat...what did I do wrong
by Marc
11/16/2007 @ 2:05pm
Now, I tried leaving the white wire connected to the W and putting a jumper between W and Y. The same thing happens though, the A/C will not turn off. It comes on as soon as I flip the switch on the unit to cool and will not go off.
by Marc
11/17/2007 @ 5:24pm
Trying to install Honeywell RTH3100C, non-programmable thermostat. My bird removed and completely severed all wires from old mercury thermostat and rendered it useless. Put thermostat in summer and the A/C worked fine. When I tried to test heat recently, EVERYTHING DIED!!! Voltmeter indicates no power coming from the 24V side of the 240/24V stepdown transformer. Replaced. Now nothing. I've got the following wires coming from my wall: Tan, black, white, red, orange, yellow, green, blue. I am trying to fit them into slots labelled as: E, Aux, Y, G, O, L, R, B, C. Unit indicates C is optional with batteries. Honeywell's worthless site doesn' t support this unit; phone number goes to automated system. Please help me get some (preferrably hot) air moving...it's getting unbearable in here.
by Jason
11/17/2007 @ 6:53pm
We were so desperately to wire TWO un-labeled WHITE wires from White Rodgers to Honeywell RTH7400. Nothing worked until we found your page, then the furnace went up with ONE try. Great JOB!
by Mori
12/1/2007 @ 2:04pm
I had the old honeywell thermastat with 2 wires...& we followed the advice on this site and put the black in the R and the white in the W in the conventional rows in the new programmabe honeywell RTH7000 series. But, we left the jumpers in...so don't forget to remove the jumpers..lol..
And thanks again for your help everyone!
by Cee
12/1/2007 @ 5:21pm
WOW! your little Blurb here jsut cost me a 200+ service call for not having heat! Ive been having proplems with my Propane furnace going out. Problem seems to be that the wires that were atached had nothing to do with color! as your blurb stated! switched them not the furnace is cycling like normal TX!
by Jay
12/1/2007 @ 5:22pm
I meant SAVED me the 200+ service call ;)
by Jay
12/8/2007 @ 5:50pm
I purchased a Honeywell RTH7500 to replace an old York mecury thermostat for my heat pump system. I followed the wiring scheme to the letter, but I have no heat! The fan auto setting does not work and we you turn it to manual it just blows air ! Below is the wiring scheme I converted from the guide.
Old New
W-White AUX
B-Blue C
G-Green G
Y-Yellow Y
O-Orange O/B
R-Red R (Which is Jumpered to RC
X-Black E
Please help!!!
by Tony
12/15/2007 @ 4:44pm
Thank you everyone so much for your helpful comments! I had a red and blue wire attached to an old Honeywell round thermostat and the instructions for the new digital Honeywell RTH221 were no help.
R (which was actually the blue wire) at 6 o'clock
W (which was actually the red wire) at 8 o'clock
did the trick!!!
P.S. So *that's* what a mercury switch looks like....I will dispose of it properly.
by Handywoman Linda
12/15/2007 @ 4:51pm
Changing from a double mercury T'stat on a PD series Magic Chef heat pump. Old Terminals: C(Black), W2(Green), G(Blue), Y1(Yellow), W1(White),E(Orange),X1(Brown),R(Red) Need to wire to a Honeywell RTH3100C with E,Aux,Y,G,O,L,R,B,C.
Thanks
by Ron
12/20/2007 @ 4:44pm
I'm trying to replace an old Trane Weathertron with a Honeywell RTH230B. The Weathertron has 8 wires coming into it. The Honeywell has just 5 terminals. Here's the list of 8 wires:
R
T
O
G
Y
X2
B
W
The replacement has Rh, Rc, W, Y, and G. Help please!
by Oscar
12/22/2007 @ 5:24pm
Dude, brilliant bit of info - thanks so much!
by phillycheese :-)
12/26/2007 @ 12:22pm
I'm trying to install 2 T410A thermostats in an all electric building. There for a ceiling heating system. There were only 2 wires.. blue and black. But the blue wire was the hot wire. I attached the hot/blue wire to the L1 (top) and the black to the T1 )bottom. This didn't work. I guess I'll just switch the wires and hope it works. I tested the wiring, so I know there's power to the recepticles.
by Jim
12/30/2007 @ 2:44pm
Thank God for your posting. My almost 90 year old house did not have colored wires or letters on the old round Honeywell and the Honeywell site was of no use at all. My new RTH6300B is now installed and working beautifully thanks you.
by Jean in Baltimore
12/31/2007 @ 2:03pm
I just upgraded our mercury containing Honeywell to the RTH6300B you used and thank God I found your site! The Honeywell instructions gave no inkling as to what to do with 2 unlabeled wires... THANK YOU! Works like a charm, R & W as you said...
by Shawn
1/1/2008 @ 2:25pm
You are a certified God for putting up this how-to guide!!!
I bought a home with the exact same thermostat that was originally installed in 1952. I wanted to replace it but was discouraged by the lack of information on how to replace a thermostat. Most of the current information is tailored towards replacing digital thermostats and not analog.
I called some contractors and they were giving estimates from $150-$350.
Thanks a bunch for putting this up!!!
by Ash
1/2/2008 @ 12:44pm
What a great helpful site. In hindsite I did everything right except leaving the jumper wire on. Thanks a bunch!
by John
1/2/2008 @ 1:17pm
Thank you, thank you, thank you. Your website really helped me out with my OLD Honeywell thermostat. The old one wasn't labeled at all & Honeywell was zero help. Now my new one, the RTH230B is working!
by Mike
1/5/2008 @ 5:49pm
I had the exact same thermostat as you, put in a house originally built in 1967 and was trying to replace it with a Honeywell RTH8500. Farted around with Honeywell support for a while before finding this page - problem solved! Cheers mate
by Alan
1/6/2008 @ 8:37am
Great place you have here.
If anyone here needs a manual or installation instructions for a Honeywell thermostat visit this site:
http://yourhome.honeywell.com/Consumer/Cultures/en-US/default.htm
Just enter the model number on the right pane under "Owners manual & Literature Search"
Also available is a The Thermostat Wizard that might help you with wiring
by J. Salce
1/8/2008 @ 4:18pm
Nice. I, too, had the same problem. I, like most other comment posters, searched the web to no avail. Your information gave me the confidence I needed to finish the job without fear of burning my house down. Thanks!
PS- I tried that Thermostat Wizard. The model of my old thermostat wasn't listed...
by James Frederick
1/13/2008 @ 8:25am
I just finished looking around on the web for useful info about
this classic thermostat. You'd think there'd be more info since it
was used so much in residential installations.
I did a double-take at your photos. It looks exactly like mine,
right down to the stucco walls. My house was built in 1914,
so it's anybody's guess when these thermostats were installed.
I was initially looking for maintenance info on these devices.
But, I may try replacement using your info, if cleaning them doesn't work.
Thanks...I may be back.
-Doug
by Doug
1/15/2008 @ 10:56am
i need to replace a ge weathertron thermostat that is a 1979 mercury bulb with a carrier programmable
the carrier has term. forw/w1-y/y2-g-r-y1/w2-o/w2*-s2-s1-l-b-c the old ge has term.r-o-g-y-x2-b-w-F
how do place wires on carrier
by mike stalvey
1/15/2008 @ 11:09am
I negleted to say F term on ge is empty
by mike stalvey
1/16/2008 @ 4:52am
my memory is bad but I think it might be helpful if I gave you the wire colors.
The GE weathertron
R=red
T=brown
o+orange
G=green
Y=yellow
X2=black
B=light blue
W@=white
thanks
by mike stalvey
1/16/2008 @ 8:42am
I presently have White-Rodgers, Model 1E30-910, heat only, wall thermostats. Is a White-Rodgers, Model 1E30-211 a compatible replacement for the White-Rodgers 1E30-910? The 1E30-211 looks exactly like the 1E30-910, both are two-terminal, and both have mercury contacts. Thank you!
by Jack
1/22/2008 @ 4:40pm
Replacing 5yr.old Baystat240A with a new Honeywell 3100C.
Need help wiring.
Old Baystate Color Code
R-Red
T-Tan/Brown
O-Orange
G-Green
Y-Yellow
2X-Black
BL-Blue
U and W have a jump Wire
New Honeywell Code
E-
Aux-
Y-
G-
O-
L-
R
B-
C- That says Optional With Battery
What wires go from old Baystat to new Honeywell
Need Heat
by George
1/23/2008 @ 12:56pm
I HAVE A OLD 70'S STYLE RECTANGULAR WHITE-RODGERS THERMOSTAT THAT I WANT TO REPLACE I TOOK THE OLD THERMOSTAT OFF THE WALL. LOOKED ON THE BACK FOR WIRE LABLES BUT THERE ARE NO LETTERS ON MINE HELP PLEASE. IM REPLACING IT WITH A RTH3100C HONEYWELL STAT.
by JOHN ROBERTS
1/24/2008 @ 7:37pm
Hi.
I am replacing and old White-Rogers 1F35-910 Mechanical thermostat that had three wires labeled as such: R5, Y6 and 4. The wire colors are white, red and dark green. I am assuming the white is common, D Green is power and Red is stop heat. I found this online as someone else had the same problem but so far, no heat from boiler. Any suggestions?
by John Trujillo
1/26/2008 @ 1:15am
i have an old mercury thermostat with 2 wires, one is red and one is whiteish yellow connected to it, how do i connect the new rth230b, i tried to connect the white and red and nothing happened. i have a electric fan heater thing. please help me.
by richie
1/26/2008 @ 1:18am
there are other wires coming out of the wall but they are not connected to anything...
by richie
1/26/2008 @ 1:20am
the old one is a white rodgers 2 wire
by richie
1/26/2008 @ 2:06am
i fixed it, i through the mother fuckker into the street!
by richie
1/26/2008 @ 2:41pm
You probably already know this, but mercury is associated most closely with brain damage, rather than cancer, because it can cross the blood-brain barrier. Mad Hatter, ya know. If you google "Minimata," you'll see some pretty terrible stuff mercury can do. Thanks so much for the post, it'll help where the instructions with my new thermo were no help at all. =)
by Axolotl
1/26/2008 @ 2:43pm
Oops, "Minamata."
by Axolotl
1/27/2008 @ 3:04pm
Some of you were lucky enuf to have red wires, each of my 4 wires was either black or white. Well, the new thermostat is installed and it does work - after a fashion. It does not go off - ever. Could it be that something is wrong with the furnace instead?
by Sara
1/29/2008 @ 3:35pm
John Trujillo, did you get it figured out??? i'm having the SAME issue right now. the new thermostat has the connections: G, Rc, Rh, Y, W. My system has Y6, R5 and 4...
WTF!?!?!?!
by Kate
1/31/2008 @ 6:42pm
So, has anyone come up with the White-Rodgers 1F35-910 solution yet? I have four of these cursed beasts in my house controlling zones for my hydronic heating system, and want to replace each with a Honeywell RTH110B. All three wires on the existing thermostat go to their respective zone control valves, but from there I'm lost. White-Rodgers still makes the 1F35-910, and their recommended replacement is the 1F97-1277 - but even then the terminal designations on that thermostat doesn't have the Y6, R5 and 4.
by Bill
2/5/2008 @ 3:05pm
I've been researching this for the past few days. Has anyone tried:
Rh = R5
Y = Y6
W = 4
As the connection for a 3-wire heat thermostat?
Honeywell's T87K thermostat, which allegedly works as a replacement for the 1F35-910, shows this connection. The T87N, which is for AC as well as heat, also shows the W terminal as the heat relay, which is what the '4' connection is on the White-Rodgers.
Comments?
by Bill
2/29/2008 @ 9:44pm
i really need help i got 8 wires coming from my old bryant tstat, and i cant figure out what wires go where on this new honeywell rth230b only has 5 terminals: rh, rc, w, y, g. on the old one there were : w2, o, x, e, y, r, g....
im so confused, the w2 has a white and blue wire in its terminal, x=black, e=tan, o is orange, y is yellow, r is red, and g is a green wire. can some one please help me. its cold up here. thanks
-tim-
by tim
3/1/2008 @ 3:36pm
Thanks very much for this blog. I had the same problem today with wires of unknown source and no discernible resources to figure what needed to connect to what. Your blog gave me the confidence of which wires was which (I had a red and white stripey wire too) and I connected them as you suggested and voila! it works!
by Diane
3/8/2008 @ 7:22am
thanks for the timeless info! For anyone with an old (but remember - it is unique & charming!) house that constantly has 'surprises' waiting for us with each new renovation project, your info came in handy.
by claudia
4/4/2008 @ 6:17pm
I have a Lennox 36G 6901 with 9 wires and am trying to fit a Honeywell RTH7000, and not having much success as the Lennox codes/colors don't seem to match anything. Any help or suggestions on finding color codes/diagrams for the would be greatly appreciated.
Thanks.
by Mark
4/12/2008 @ 5:39pm
Wow, I must be really backwards... In my 20's house, I'm replacing a 70's 4 wire electronic Tstat with a 1920's 2 wire T-stat, to actuate my gas furnace. I've already replace all my 60's wall switches with old 20's push button switches. So happy I found this sight... and learned the mantra... "red and white, red and white". THANKS! Mike in Seattle
by Mike Flahery
4/17/2008 @ 10:10pm
Dear Sir,
I want to replace my old honeywell mercury thermostat (model t8085d 1008) with a new non-programmable thermostat. Would you please tell me what is the correct thermostat for me. Thanks.
Regards,
Canaanlee
by canaanlee
4/25/2008 @ 3:37pm
I have a coleman unit , to change from heat to cool you have to do it by a switch on the front of the air handeler. No biggie . I want to replace the old mechanical thermostat with the honeywell rth 221 . I have 2 wires to the thermostat RED and BLUE . and thats it . I hooked up to rh red and w blue ( jumper to rc in place ) and its will not shut off automaticly . Whats the deal ? Any Help out there ?
by Phil
5/8/2008 @ 8:04am
Thanks...this helped a lot!
by Andrew
5/21/2008 @ 11:59am
I want to replace an old 2-wire round Honeywell thermostat (2 wires are from furnace primary control), with a Honeywell T8601D. I know I need a 3rd wire (common), but am uncertain as to what wires are connect to where (on the new thermostat, as well as on the furnace). I'll appreciate any help and/or a diagram.
Thanks.
Robert
by Robert
6/9/2008 @ 5:16pm
Problem with replacing the White-Rogers old one in my house is had to get the front off....not the cover...the front. 3 small screws that looked like electrical connections. Once those were off, all the wires and letters appeared!!! Then it was easy.
by Rob
6/13/2008 @ 10:04am
Two thermotats-both identical installs:
All my wires have the listed colors matching an old honeywell 'round' thermostat, no problem with the color codes or how they were wired. (Red, Green, Yellow, White, Blue wire never unused) Yeeeetttttttt...only the fan switch comes on when switched to the 'fan on' mode. No compressor, no heating, hmmmmm. I stopped what I was doing to give the process a fresh look later today.
This really should have been a simple replacement, Yes/No?
by Chuck
6/21/2008 @ 3:48pm
Wow...this 30 minute job took hours and it's 116 degrees in Phoenix right now. I had the old mercury style Honeywell with 4 wires. There is no help to be found out there with the internet or with the Honeywell website.
Thank God I found this post. The website "Darren" sent out was very helpful and I now have air. If not for this post I would have had to wait till Tuesday to get someone in here and I'd be $150. poorer. Go to:
hammerzone.com/archives/hvac/controls/tstat1/replace.htm
Thanks Kevin! I'll bet you never dreamed this post would go on for 3 years now.
A bit cooler now,
Dawn
by Dawn English
6/22/2008 @ 9:14am
Happy it/I/everyone could help. Enjoy!
by KevinFreitas
7/10/2008 @ 7:59pm
Yes, great site but haven't seen my particular situation just yet and hoping you can help!
Trying to replace a White-Rodgers 1F56-444 with a Honeywell RTH230B programmable 5-2 thermostat (similar to the 6300?). It's a condo unit and we have both heat and central air. The current settings/mappings are:
G - Blue
Rc - Red
Y - Yellow
W - White
A - White
Bridge from Rc to RH
How do these map to the Honeywell?:
Rh
Rc
W
Y
G
I assume the common letters map, and the Honeywell has a built-in Rc-Rh bridge, but then what do I do with the other white wire currently connected to A?!
by JD
7/16/2008 @ 6:24pm
oh thank the lord for the link to the 'wiring wizzard'. I had a white rodgers single stage low voltage that had G, RC, Y, W, and 4. who'd ever heard of terminal 4? What the heck was I supposed to do with terminal 4? Anyway, it ended up that my Honeywell RTH5100B has an R terminal.......the '4' wire goes to the R terminal.
Hint....don't worry about the colours of the wires if you have the terminal names.
thanks
by Paul in Hamilton On
7/26/2008 @ 12:55am
hello,
i have old lennox thermostat that has seven wires.
out at the pump the wiring diagram is like this.
Y- the wire is orange
R- the wire is black
V- the wireis blue
M- the wire is red
X- the wire is yellow
F- the wire is green
the white wire go auxiliary heat
ok i'm trying to hook my new thermostat
with is a honeywell rth3100c
the two diagram are not the same
by Dan
8/3/2008 @ 12:44pm
We bought a programmable thermostat to replace our very old round Honeywell. Had the same problem as alot of people on this site being the wires not marked. We have a red, a white and a green that was cut off. We had 2 programmable thermostats installed years ago by a heating company, so I took the covers off to see where those wires went. To my surprise, one of them has the red wire going to RC and the white to W, the other thermostat has the red wire going to RH and the white to W. They have been working fine so I am baffled as to why would it connect to RC when we don't have A/C? Our heat is hot water baseboard, oil fired.
Thanks.
by Casey
8/5/2008 @ 9:34am
I'm installing a 2 stage gas furnace and I have a noma 5-1-1 programmable thermostat #52-2558-8
It calls for a 2 stage thermostat. Can I use my Noma.
by Mr. B
8/5/2008 @ 2:40pm
I am installing a new Honeywell RTH3100C thermostat to a Trane AC with a heat pump. I read the posts and connected the wires to the terminals:
E terminal with Black wire
Aux terminal with White wire
Y terminal with Yellow wire
G terminal with Green wire
O terminal with Orange wire
L terminal left empty
R terminal with Red wire
B terminal left empty
C terminal with Blue wire
The AC works fine, but the Heat Pump does not come on.
I must have one of the wires (heat) connected wrong.
Please, please, does anybody know what is connected wrong???
Thanks,
Bob
by Bob Fryer
9/1/2008 @ 6:08pm
I would have never been able to replace this thermometer- or rather get the courage...if it wasnt for this website. Thanks so much!
Angela
by Sir Not-Appearing-In-This-Flim
10/4/2008 @ 2:05pm
This site appears helpful, but I didnt see my situation, and I tried the Honeywell wiring wizard but it doesnt include my model.
I currently have a White Rodgers (9510E7) rectangular thermostat and I am trying to replace with Honeywell 5-2 Day Programable RTH230B.
Currently there are 8 wires comming out of the wall
Blue- not connected to anything
Black- not connected to anything
Red- R
Brown- C
Yellow- Y
White- W2
Green-G
Pink- O
The new thermostat only has room for 5 wires. Some are straight forward, but others are confusing. The outlets are:
Rh- Heating Power
Rc- Cooling Power
W- Heating Signal
Y- Cooling Signal
G- Fan
*Jumper wire between Rh and Rc.
Can someone please tell me what wires connect to the Rh,Rc,W,Y,G Honeywell outlets and which are not used (and possibly why not used). Thanks in advance!!
by John
10/15/2008 @ 8:08pm
Thanks for the instructions! This worked like a jiffy. Although I had a hard time distinguishing wires because there was very faint indictation of color. I had an old Honeywell just like yours but I had three wires: The Red and White striped (I think it was striped but it was VERY Faded) I put into the W like you suggested, The blue and white (very faint blue) I put into the G and the White I put into the Rh.
by Sally
10/18/2008 @ 4:20pm
changing old thermostat to RTH8500.
i have the following cables and colors:
Y - orange
W - yellow
R - Red
G - Green
A - Black.
What the heck is A. Honeywell conversion chart doesnt have A. Bloody A.. Please help!
by Aaron
10/21/2008 @ 11:40am
If the furnace was not switched off on the fuse would that cause the new thermostat not to work?
by Lina
10/21/2008 @ 10:12pm
>
I have an old white rodgers thermostat (Model: 1E30W-311). The two black identical wires from the wall, are connected to two UNLABELLED terminals of the thermostat, one on the left and other on the right terminal. I want to replace this broken thermostat with NOMA PROGRAMMABLE THERMOSTAT THM501. The brochure mentions that in case of 2-WIRE HEATING, connect HEATING RELAY wire to W, and the other wire to RH. THE PROBLEM IS THAT, THERE IS NO DIFFERENCE BETWEEN THE TWO BLACK IDENTICAL WIRES. So, which one to connect to W and which one to RH.
PLEASEEEEEEE HELP, I AM FREEZING ALONG WITH MY 5 family members..... WAITING (albertwl627@yahoo.com)
by Sir Not-Appearing-In-This-Flim
10/23/2008 @ 6:20pm
Oooh mercy!! You are wonderful, fabulous, a life saver and I think I love you!
I was at my wits end trying to figure this out when I happened upon your site!
I was trying to replace an old American Standard thermostat - the kind with the little vial of mercury in it. The new thermostat had all kinds of instructions for wiring that did NOT exist on my old thermostat. No wire labels anywhere. One black, one white. That's all I have. Dilemma: which one goes where? Following the procedure described here I put the black wire on the R terminal and the white wire on the W terminal (the R terminal has a jump wire on it from the factory) and wha-lah! Perfect!
Now when my husband gets home from his trip I'll have this new fandangle thing all done! I've even figured out how to program it! I amaze me.
Thanks for taking the time to post this wonderful site!
My house was built in 1897 and I'm still running old water heat with radiators ~ wonderful heat by the way ~ and it's up and running like a champ!
Oh, Sir Not-Appearing-In-This-Film >Sounds like to me it doesn't matter which way you connect them. One way will work and the other won't. A person above did it one way and it didn't work, so they switched them and it works. He didn't mention any problem created by the backwards hooking them up... just my guess... but if it didn't hurt his....???!!!
by Sir Not-Appearing-In-This-Flim
10/24/2008 @ 11:29am
I have a rectangular White Rodgers that I will try to replace with a Hunter Modell 44110. None of the wires are labeled, I have green, yellow and tan - it also looks like I have a glass tube with mercury in it. Actually, I can't even figure out how to get the base plastic piece off the wall, the screws are inset in the wall through a teeny hole in the base mounted to the wall. Help.
by Sir Not-Appearing-In-This-Flim
10/24/2008 @ 1:19pm
What a useful site! I just went from an old mechanical Lux CH200 to a programmable Lux, and of course there was no label on the leads in the old unit. I had a red wire and a brownish wire to connect, with a 50-50 chance of getting it right by guessing. In the old device, the red wire connected to a red wire on the left side in the thermostat, and the brownish one went to the other screw on the right. I determined that the red wire went to the RH connection and the other to the W. And it worked!
by Sue W
10/26/2008 @ 7:33pm
I have a house built in 1921 - it is complete with radiators and good, old fashioned steam! My 'red and white' wire was black - without this post I would never have thought to use the 'R' connection - I was trying every other combination except the R! Thanks for the tip!
by Sir Not-Appearing-In-This-Flim
10/31/2008 @ 1:37pm
Well, there aren't supposed to be labels in the old ones....the DIRECTIONS (lol) that come with every new one say to very carefully label the old wires with the labels that come in the package BEFORE you remove them from the old frame, there is a key in the package too. eg., red-y blue-w and so on, so that you can connect them again. Even with this I still had an issue with mine, but it goes to show how few people read directions:)
by Sir Not-Appearing-In-This-Flim
11/7/2008 @ 1:56pm
Any idea on the voltage for the electric clock on the old Honeywell clock-thermostats? The electrician who hooked up the new boiler threw away the old transformer. The settings still work but the clodck doesn't. Think it would be OK to hook up a model train variable transformer and crank it up until the clock runs smoothly?
by Lalor
11/11/2008 @ 6:35pm
I hope you can help! I'm replacing a white rodgers model # 1F58-77 thermostat,
Y-yellow
G-green
R-red
W2-white
X1-blue
B-brown
with a Honeywell T8411R
G
C
R
W1
Y
L
W2
E
B
O
Would you please help me figure out what wires goes where?
by Crystal
11/12/2008 @ 11:09am
I have a White-Rodgers t.stat with the following wiring....
Yellow - Y
Blue - C
Green - G
Brown - O/B
Red - R
White - W2 & "jumping" to E
Would like to replace that with a Honeywell 7400 series
1. Is that the right Honeywell model to use ?
2. If so, how to wire ?
by Randy
11/16/2008 @ 3:05pm
I had an old White Rodgers Thermostat and tried to replace it with HoneyWell. Like most people here, there were no letters. Only had BLACK and WHITE wire. I plugged the BLACK in R and WHITE in W and it works perfectly.
by Vico
11/18/2008 @ 8:01am
what is the s1 wire on a bryant thermostat?
by Ed
11/19/2008 @ 2:38am
LORD. I am single and a woman...LOL does that say enough? I replaced my old Bryant 1976 thermostat with the Honeywell RTH221 programmable thermostat and well it turns on and heat comes out but the thermostat keeps kicking the heat on LITERALLY every 10mins. I have central gas heat and central air...both the furnance and AC were replaced in August of 2008.
I had 4 wires
Y- Blue Wire
G- Green Wire
R- Red Wire
W- White wire
I plugged the blue wire into the Y, the Green into the G the W into the W and then the Red wire into the RC slot...I had tremendous trouble unscrewing the little screws that hold the wires IN place so it told me to remove the little jumper thingy that was between RH and RC...could this be my problem? Since I removed the the jumper thingy thats why my thermostat keeps kicking on every 10mins on the DOT! lord.
ANY HELP WOULD BE APPRECIATED
by Amity
11/22/2008 @ 7:45am
Thanks for the tip......Worked perfectly!!!!
by Jerry V
12/8/2008 @ 7:03am
Thank you so much this was a god send article.. Im a 33 year old female and did it all myself Thanks to you and everyone elses comments.. Its nice and warm in here finally
by sam
12/10/2008 @ 9:17am
Thanks for the help. Wow,a lot of help from a lot of different people!!! I used the advice for the black and white wire attachments. I found a 3rd red wire hidden under the old thermostat when it was removed, so I left it hidden. Everything works great!
...black to R, and white to W. Keep the R & Rc jumper attached.
by Brigitte
12/13/2008 @ 3:13am
I have a honeywell rth 7000 series and i installed it myself about 3 months ago. recently a red light has been coming on periodically. Does anyone know what it means i've checked the net and all the booklets it came with and i couldnt find anything
by JA
12/14/2008 @ 2:21pm
Can anyone help me. I have a gas system with fan. When I removed the old one there are only 3 wires, a red, white, and green. I purchased a new Honeywell CT87N. First question, is this the right one, and secondly the new one has a jumper to R and Rc, Do I remove the jumper and use only the R or what do I do. Please help me for it is below zero in Montana where I live. Thank you.
by Dorothy
12/18/2008 @ 9:03am
Perfect! i was so discouraged when I took the face plate off of my old Honeywell thermostat and only saw 2 wires! I tried calling Honeywell and the phone lines were so busy they disconnected me! The website was NO help at all! I found your quick fix and had my new programmable thermostat running in no time! The R wire is found at o'clock and W is found at 8 o'clock. Easy! Thanks a bunch!
by Sir Not-Appearing-In-This-Flim
12/26/2008 @ 10:42am
I am spending the $100 - 150 to have a professional do it. I have 5 wires, no labels, no way to tell WTF I am doing.. give up.
by Sir Not-Appearing-In-This-Flim
12/31/2008 @ 9:02am
This site saved us ALOT of heartache, we spent all morning trying to figure this out then stumbled on this website, exactly what we were looking for! Thanks a ton!
by David
1/5/2009 @ 12:30pm
You are my hero! Thanks for this site.
by myboyzr2
1/5/2009 @ 2:56pm
I just want to replace my old T8085D Honeywell for a replacement thermostat. This old Honeywell has 5 wires connected, B,R,G,Y,W,. Do I need to find a replacement thermostat with the exact same wiring or will a universal thermostat work?? Any ideas which model??
by Sir Not-Appearing-In-This-Flim
1/6/2009 @ 6:12pm
I WILL TAKE ANY MERCURY YOU DO NOT WANT i love the liquid metal and i am a element collector so i really like this element WILL TAKE THEM
by element collector
1/10/2009 @ 6:06pm
Can't set the clock on a Honeywell RTH230B. I had one for a few years and had to change the batteries recently but after putting new ones in I could not set the clock (hours and minutes continuously blink after holding down the clk button). So I go and buy a new one and the same thing, clock blink and even after holding down the clk button I can not adjust the time at all. Everything else works fine but I would like to be able to program the thing.
Thanks
by Sir Not-Appearing-In-This-Flim
1/11/2009 @ 9:13pm
I am trying to replace a 1980s Honeywell Round T87F with a Honeywell programmable TRH230B. I have an oil furnace with hot water baseboard heat with zone valves. I have 3 wires from wall - red, white and green. Tried the red in Rh and the white in W and took out the jumper cable- no luck. Do I need to put in the green into G which is labeled fan and put back the jumper cable to make it work?
Thanks so much for your help!
by Noni
1/17/2009 @ 6:54am
I found this site interesting, and feel for people frustrated with these situations. May I suggest backing away from the wire colors and numbers or letters and take a few minuites to see how the circuit works? You don't need to be an electrical engineer, just buy a 5 dollar VOM volt ohn meter, read the instructions that come with it or look up a site for instructions.
With the thermostat on the kitchen table and a little patience you can teach youself simple cuircuits then you will be able to wire any type of thermostat. Of couse it would help to kown the circuit to the boiler, furnace or A/C, but as long as you can tell the difference between a wire with voltage and a wire closing a circuit you will have it licked. No one can help you over the internet if the wire colors are not the standard in the field. I.m going to try to get some time to post some simple circuits. Once you know how to use the VOM, you can troubleshoot and repair many other household items.
Safety first, watch out for line voltage 110V and 220V some old house actually have live voltage thermostats!
Good Luck to all
Matt
by Sir Not-Appearing-In-This-Flim
1/17/2009 @ 3:13pm
Thanks for the help!
by Rick
1/19/2009 @ 5:47pm
thank you so much! my story was identical to yours, i was so frustrated by honeywell's assumption that everything would be clearly labeled.... i had two exposed copper lines... no labels.... this was endlessly helpful.
by mike
1/21/2009 @ 4:46pm
The amount of stuff you can find answers to on the web is unbelievable, such as, which wire is the heating signal wire on an ancient Honeywell thermostat from the 1950s. Honeywell doesn't have that info at their own site but Kevin did. The power of the web! Installing a new stat probably cost 100 - 150 if you can't DIY.
thanks - you saved me $$$!!!
by Marc
2/10/2009 @ 4:29pm
I'm replacing a white rodgers 1F58-77 thermostat,
Y-Yellow
G-Green
R-Red
W2-White with jumper to E
X1-Blue
B-Black
...with a Honeywell rth3100c
C, B, R, L, O, G, Y, Aux, E
Would you PLEASE help. Thanks!
by Mike
2/16/2009 @ 6:23pm
I am trying to install a rth3100c. what is the wiring diagram? I have a black, white, yellow, green, orange, red, blue.
on the rth3100c it reads
e,aux, y, g, o, l, r, b, c
by wes
2/22/2009 @ 10:28am
Hi Kevin, I am trying to install a t-stat. Here goes: My old honeywell/mod th3210d-0739 has E,Aux,Y,G,O,L,R,B,C. E=brown wire, Aux=white wire, Y=yellow wire, G=green wire, O=orange wire, L=no wire, R=red wire, B=no wire, C=blue wire.
My new Lux/programmabe/model tx9000ts has W,Y,G,B,O,Rc/Rh, C. I connect E(brown)to B, Aux(White)to W, Y(yellow)to Y, G(green)to G, O(orange)to O, no wire to L, R(red)to Rh, C(blue)to C. Is this correct??? help I am a single mom with two teenagers.
by Debbie
3/7/2009 @ 3:58pm
I just bought a Honeywell RTH7500 Thermostat. Hookup was easy enough but I'm afraid i'm locked into the wake-leave-return-sleep schedule the thermostat offers. I've changed the times, but it doesn't seem to want to let me do away with the leave and return portions of the schedule. In other words, all i really want is wake and sleep. I can't find in the manual how to override/ignore the leave/return. Thanks you for any suggestions.
by David
3/29/2009 @ 11:49am
i have installed plenty of thermostats and i have never come across one that has a wire labled t and now i have an ac unit that wont work if some one could email me and help me out every thing else hooks up right i just dont know what to do with that
by Sir Not-Appearing-In-This-Flim
4/7/2009 @ 9:07pm
I installed a Honeywell RTH230B about 6 months ago and was quite proud of my accomplishment. Unfortunately, when my bro-in-law was in town, he 'secured' the outside of the thermostat because it was very well attached to the wall. Now my A/C does not work, sooooo .... I took off the thermostat and discovered that he had wound my dark orange wire around the other wires & stuffed it into the wall! Not only that, but now ... by some miracle ... I now have not one but TWO tan wires coming out of my wall.
Now I'm stumped and have lost all of my previous bravado. The colors hanging out of my wall and my attempt to attach them are:
RED ........... RH
ORANGE .... RC
BROWN ..... G
TAN ........... W I twisted the 2 tans together!
DKBLUE .... Y
And, should I use the jumper wire between Rc and Rh? I think I used it before this mess, but when I opened it up this time, it was connected, but it was on the top of the wire connection panel, not under it!!!!
Whoa is me ... after the bro-n-law left, I could only get heat from the tstat, no a/c which is why I took the thing apart.
I'm in Vegas ... my upstairs temp 2day was 84 ... a small preview of things to come ... YIKES ...
PUHLEEZE HELP ME ... SOMEONE ... ANYONE ... I AM SO INCREDIBLY FRUSTRATED I FEEL LIKE CURLY FROM THE STOOGES!
Cannot access an electrician ... already in bankruptcy and barely holding onto this soon to be an oven of a house ....
HELP ME .... I'M MELTING !!!!!
BRAINBURP928
by Sir Not-Appearing-In-This-Flim
5/22/2009 @ 6:34pm
i just bought a new t-stat i have red,white,green,blue,yellow wires i hooked up the red to the rc,with the jumper going to the rc and r than the yellow to the y the green to the g and the white to the w and left the blue undone but now the blower is working but my central air unit is not kicking on what iam i doing wrong please help me
by tammy
6/6/2009 @ 3:45pm
I bought a Honeywell RTH3100C thermostat, to replace a mercury one, I have 4 wires off the wall, White, Blue, Green and Red.
I install the Red to R, Blue to Y, White to W, and Green to G. The A/C works OK, but when I switch to Heat, then the heat and A/C compressor are running together. Do I have a short some where or wrong wiring.
I really appreciate your help.
Nik
by Nik
6/24/2009 @ 2:01pm
HI Kevin,
I have a old thermostat white rodgers with a small tube of mercury in it. My old thermostat is a manual one with 2 levers on the right side for hot and cold control.
My question is how do I take off that mercury tube and do we need that to be put in the new thermostat or just dispose it off.
New is from Honey well any help is appreciated
Thanks
dnyanesh
by Dnyanesh