I have an old ITT General Controls (mercury switch) thermostat for our electric furnace. I am trying to replace it with a Honeywell RTH230b thermostat. The old wiring has four wires (two white and two red) which are attached to screws labeled "F, H1, H2 and V". Looking at the wiring diagram on the inside of the Wesco Furnace "Model 20UE-H,R,S" it also shows the wires coming from the bus labeled "F, H1, H2 and V". There is not an A/C unit or Heat Pump. Currently, the ITT thermostat has a switch which will turn on the fan only. I am assuming I need to hook up the wires to Rh (leaving the jumper in place between Rh and Rc), W and G. But which wire goes to which? I have also switched the Honeywell jumper from HG to HE for an electric furnace. Any thoughts or help?

Kurt

WOOPS I believe your ITT General control/thermostat is designed for operating a two stage heat system. The give away on this is the H1 and H2 designation on the furnace and on the bus.

So what you really need is a two stage heat thermostat and almost all of them will have a fan control switch. So I believe you will need to take back the thermostat you just bought and get a different one.

You next problem you will also need to figure out unless you labeled the wires off the old thermostat before removal. For proper wiring you actually need 4 different color wires so you can tell exactly where they came from (terminals) and where they go to (thermostat terminals). You have two red and two white wires so I have no idea which red or which white is actually attached to which terminal if you catch my drift on this.
Unless you marked them EXACTLY from which terminal they were on at the old thermostat you run a good chance of damaging the new thermostat due to improper hook up.

BTW here is your manual. See top left page one where it says it will not work with multi-stage equipment. See under NOTE

http://customer.honeywell.com/techli...0s/69-1800.pdf

Thanks for the quick response. I have actually NOT disconnected the wires from the old thermostat so that we can continue to use it while we try to figure out the wiring for the new thermostat. The problem with the old unit is that you need to turn it up to 90+ degrees to get the furnace to kick on and down to 50 degrees to get it to shut off. Makes for quite cold nights if you leave it off and the temps are getting down in the teens. Also made it hard to tell if it's is a single or two phase system. Does this mean that we have been using it as a single phase system the whole time because we are turning it up to 90+?

So, your response about the two phase heater was what I was afraid of, only because it means another trip to town for the right thermostat. Beyond that, once I do get another unit, where will the F and V wires go to? Is the F for Fan? BTW, the red and white wires are not in any particular spots as H1 is Red and H2 is White, F is Red and V is White.

The term is STAGE not Phase.

Does this mean that we have been using it as a single phase system the whole time because we are turning it up to 90+?

That is possible and it indicates something else might be wrong with your furnace other than the thermostat.

Beyond that, once I do get another unit, where will the F and V wires go to? Is the F for Fan? BTW, the red and white wires are not in any particular spots as H1 is Red and H2 is White, F is Red and V is White.

As mentioned before we deal in wire colors but not like yours. I am reposting my info I posted before just in case you did not read it .

You next problem you will also need to figure out unless you labeled the wires off the old thermostat before removal. For proper wiring you actually need 4 different color wires so you can tell exactly where they came from (terminals) and where they go to (thermostat terminals). You have two red and two white wires so I have no idea which red or which white is actually attached to which terminal if you catch my drift on this.
Unless you marked them EXACTLY from which terminal they were on at the old thermostat you run a good chance of damaging the new thermostat due to improper hook up.

Now your F wire might go to G=Green on the new thermostat and the V wire might be the W=White terminal on the new thermostat. But this is all guess work from here on my part since the wire colors are not standard on your setup.

You might look at this other links post to see what someone else said about the type of wiring you have since I said before it is impossible to tell from here.

Trying to install programmable thermostat [Archive] - DoItYourself.com Community Forums

If in doubt about your units actual problem or thermostat wiring I suggest you contact a local HVAC professional for a ON site visit to your home.

Quote:

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Originally Posted by hvac1000

As mentioned before we deal in wire colors but not like yours. I am reposting my info I posted before just in case you did not read it .

You next problem you will also need to figure out unless you labeled the wires off the old thermostat before removal. For proper wiring you actually need 4 different color wires so you can tell exactly where they came from (terminals) and where they go to (thermostat terminals). You have two red and two white wires so I have no idea which red or which white is actually attached to which terminal if you catch my drift on this.
Unless you marked them EXACTLY from which terminal they were on at the old thermostat you run a good chance of damaging the new thermostat due to improper hook up.

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Well, I DID read your posts and was grateful for your help. But when you suggest that "we deal in wire colors" you must not have read my post which told you that the wires are labeled on BOTH sides (at the terminals AND the thermostat terminals) as "F, H1, H2 and V" so I know which thermostat terminals they will come off. And you must be suggesting that I buy a new house because the old house I have does not use "the right color wires". Not practical. I understand that the wires are not the typical ones used, but for a house built in 1945, I'm lucky to have wires that I can tell where they go.

That being said, your link was very helpful, thank you. From that I see that:

ITT goes to Honeywell
F G
H1 W1
H2 W2
V Rh


As for having an HVAC professional for an on-site visit, we live about 1 to 1 1/2 hours from the nearest "big city" and the hourly charge for that would be pricey. I'm trying to resolve this before having to use that option. Thanks again for the help.

The main problem I was trying to prevent is cross wiring. When you have identical color wires going to different terminals it is bad news in our industry since we(the company doing the work would be responsible if something was damaged) In your case if you damage it you live with it. I only try and answer questions the correct way so there is NO confusion and your wiring setup can be confusing unless you label each wire as removed as I suggested.

I also do not see a reason for you to be a smart since I never suggested you buy a new house and the mention of a on site professional was made for your protection not mine. You are getting this info for free and everyone who helps here just tries to help save people $$ or save them from freezing to death at this time of year.

Not trying to be smart, just trying to point out that I am stuck with the wiring I have and am trying to work with what I've got. I understand that you don't want to give advice that may be detrimental to my system. The on-site professional was a good idea, I was merely trying to explain why I hadn't gone with that option yet. And I have sincerely thanked you several times for your help. I do appreciate it.

I understand but it can sometimes be frustrating on this end. LOl The main thing is that you get it to work. Post back to this thread if you have any problems.

A pick of the old set back thermostat still in use out in the country house where a friend of mine lives. Such a deal.

Made the 3 1/2 hour round trip to the nearest Home Depot and got a new two stage programmable thermostat. Well, you really do get what you pay for. This more expensive model has directions THAT INCLUDE the wiring instructions from the older letter labels that were on the ITT thermostat. Hooked up and it's working great so far. F does go to the G terminal, V goes to the Rh terminal, and H1 / H2 goes to the W1 / W2 terminals.

I bet you are glad that is all over.