I have recently installed a honeywell digital progammable thermostat, my second.......?

Question

the first one has worked fine for 2 years. My house is 100 years old, and the one I just replaced has three wires coming out of the wall--red, white, green. The green was not hooked up, as I have no fan system (oil-fired boiler), just heat. I never turned off the power to hook up the new thermostat......when I installed it as instructed, I can't get the boiler to fire when I raise the temperature. The boiler still works--I can fire it with the other thermostat, but even when I switch the wires (which I had to try with the other one because they were not neatly color-coded), I can't get it to work. Please help!

There is no heating/cooling switch--there are separate contacts for Rh and Rc.................and I have it hooked up to the Rh (I've tried both)

Answer 1

Try reading the instructions The ones for home use always come with a lot of details. There is also this web site with details http://yourhome.honeywell.com/Consumer/Cultures/en-US/Products/Thermostats/Programmable/Do-It-Yourself/Default.htm

It includes an installation manual and an "ask the expert" link.

Answer 2

First thing - is the boiler a 24v or milivolt system? If milivolt then check to make sure new t-stat is compatible.

Then make sure that there isn't any pressure on the circuit board of the new t-stat from uneven wall or excess wire length bunched up behind t-stat. (like bending a calculator -the numbers get all messed up)

Is there a c connection on the t-stat if so c must be hooked up to the common on the transformer( opposite terminal of R(or RH))<24 volt systems only>


Also some of the Honeywell stats have an energy saving feature that prevent the system from cycling too often. Hook up to RH and W turn up the setting then wait and give it Lot's of time to fire. If it doesn't fire after a half hour then your new t-stat is toast ...It happens... exchange for new and try again

Answer 3

its really a very simple solution if your other thermostat works but the new one does not:

1. red wire to Rh on thermostat
2. white wire to W on thermostat
3. on back of thermostat set fuel selection switch to oil, and if available second switch to to hydronic or hot water (boiler)

this should take care of the issue, however if this stat does not have these selector switches on the back where you attach the wires you do not have a stat that is proper for use with oil heat

note: some digital stats have an installer set up menu through the touch screen ( vision pro ) to select your system heating type

also make sure, and this is important to turn power off to the boiler or you will run the risk of damaging the transformer that operates the boiler itself

good luck

Answer 4

Which thermostat did you get? There have been problems with the TH4110 or "Pro 4000" thermostats having bad relays in them. Your wires should be connected between Rh and W. You may have a bad thermostat right out of the box.

Answer 5

http://yourhome.honeywell.com They can probably help you. Also, if your thermostat is turned to the "heat" setting, which you would need to have it set at to work....maybe you have your wires crossed? Did your first one stop working after just 2 years? Or did you upgrade? I've had mine for 10years and it works like a charm! Maybe something is wrong with the heating system itself. Good luck!

Answer 6

Check the thermostat for a "heating/cooling" switch. Make sure it is set to heat. If it is, then you have connected the red and/or black wire to the wrong contact.

Answer 7

Get the instructions out. I believe you need to install a jumper between 2 other contacts. It may be between h and j but check the instructions. Then put it on heat and the fan switch doesn't matter, either auto or on. Thats just for central air.

Answer 8

you may need to have a jumper between RH and RC