Questions tagged [thermostat]

Mechanical or electrical device used to control a heating, ventilation, and air conditioning (HVAC) system, or other temperature reliant system.

230 questions with no upvoted or accepted answers
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52 views

Installed Honeywell R8285A 1048 control center combined with a Honeywell PRO 8000 thermostat

to operate an inline duct fan on a long run to a new addition. Thermostat in the new addition activates fan when the thermostat is set to cooling perfectly. I can use it to manually turn on the fan. ...
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2k views

Weathertron Xl1200 to Nest Thermostat

We have a Trane Weathertron Xl1200 heating pump with the thermostat pictured below and are trying to replace it with our new Nest thermostat. Our old system has a variable speed air handler and we ...
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127 views

Complete power loss in over-the-range microwave

The over-the-range microwave in my kitchen (GE, 1500W) has completely lost power. The power loss was intermittent for a day, but then at some point it never came back. I have checked all fuses that I ...
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11 views

Manually Toggling Heatpump Reversing Valve to enable cooling

Background A Radiothermostat CT80 fails to signal heatpump cooling, so jumpering the RED node with the GRN (Fan) and YEL (Cooling) node has successfully enabled cooling. The weather became cold, ...
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15 views

Evaporator fan motor does not turn on, could it be thermostat?

If thermostat freezes, will it not turn on the fan motor? It will turn on if I spin it manually. Whirlpool fridge with freezer on the bottom.
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Thermostat frozen over

I have a whirlpool fridge, with freezer on the bottom drawer? Freezer part freezes, but does not throw cool air to fridge part. Took apart freezer to check fan motor, spin the fan blade manually and ...
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28 views

No furnace fan in cooling mode while hooked to a fresh air damper controller

I added a fresh air damper and control, ( Soler Palau MD6-ES24VK) to my furnace (2006 York GY9S). The damper worked great in the winter but now that I am doing some cooling, I noticed that the outside ...
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288 views

Thermostat Upgrade, furnace C-wire reading low voltage

OK so here is the scenario. Upgrading thermostat from dumb to smart (Ecobee). I've done 2 others in my house that required re-wiring so I have a good sense for what should be done but I'm stuck. My ...
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389 views

Direct Wiring (bypass thermostat) of heatpump cooling

Last September my CT80 radiothermostat would not signal cooling despite the measured temperature exceeding the temperature setpoint. It would be nice if a relative could manually switch the cooling ...
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32 views

CT80 Thermostat Wiring Diagram Selection

Which terminal should the brown wire be connected to the RadioThermostat CT80? The original thermostat was wired as depicted: The brown wire is connected to terminal E (not F). As I understand it: ...
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29 views

Are my new thermostats compatible with my system?

My two old Lux Pro PSP511LC are dying (LCD going out on both!) so I got two new thermostats from a friend he didn't need we both thought I could use. They are the Orbit Clear Comfort 83521 thermostat. ...
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25 views

Thermostat with an external transformer

I am trying to hook up a Vine TJ-610B-W WiFi thermostat to my heater. The original thermostat had only 2 wires, hooked to R and W, none hiding in the wall. I plan to use an external transformer for ...
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1k views

C wire - thermostat - not providing power

I'm replacing my old Honeywell thermostat with a new Wifi thermostat. My old/current one is battery powered and doesn't use the C wire. I found the C wire behind the plate. I connected the c wire to ...
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53 views

Help adding C wire to furnace - Heat only system

Looking to add C wire into my furnace. Heat is currently running on two wires with older thermostats. Luckily the in wall wiring has three wires. Any help to point out the C wire for my setup? Or ...
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84 views

turn on furnace blower with temp sensor

I have a wood stove in my finished basement. I am looking for a way to turn on the blower fan of my furnace once the temperature in the basement reaches a certain setting like 75 degrees, that is ...
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144 views

How do I wire a switch between two 24V heating only thermostats to switch between thermostats?

I have a gas-fired forced air furnace which I need to control two separate heating zones from. One zone is to heat a crawl space only to 45 degrees and the other is the space temp of the cabin. I ...
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53 views

Main burner in NG fireplace goes out

What could be the reason of main burner going out intermittently. The pilot stays on. The voltage of the thermopile is 638mv when burner is off. The thermostat is a manual heat only. When I short out ...
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121 views

how to connect C wire for ecobee lite to Weil-McLain EG Series-5 gas steam boiler

I want to upgrade from a battery powered Honeywell thermostat to an ecobee3 lite. This is for heat only. My current Honeywell has two wires: Red and White. Missing is the C cable. There are enough ...
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19 views

how to communicate thermostat to turn on wood heat system when during heat pump defrost cycle

I have physically disconnected the strip heaters in my air handler but the fan still runs which I do not want. I have a wood boiler I want to run in place of the aux heat Can I disconnect the white ...
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21 views

Not sure what colors go to my new thermostat

Not sure what colors go where from my old one to my new one the old is on top and new is on bottom
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622 views

Nest 3rd Gen 24VAC two transformer issue

Hopefully this will finally solve the issue with my Nest. I bought a Nest 3rd Gen Learning Thermostat and followed the instructions to the tee. I have a two transformer system (Forced Air A/C and ...
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43 views

How to identify a c wire?

I have 3 wires coming out from the wall at my new house (red, white, blue). It is a water boiler heat only system. The tstat was already removed unfortunately. I thought the blue wire was the C wire, ...
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63 views

Heating System Premature CutOff / DIY Options?

I've collected all of the facts about my system and the problem we are seeing. We have two external air pump units outside the house and a Rheem furnace (GH36S, 36000 BTU) that appears to be working. ...
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17 views

Mercury thermostat behaving strangely

I reinstalled an old mercury thermostat. Heat and air both work, but they won't cut off until I move the thermostat switch to Off. In other words, when the switch is on Heat, the furnace and blower ...
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74 views

Lennox G12D2E-55C-6 with a Johnson Control G779LHA-1 ignition control and Mercury Thermostat

I am looking to replace the mercury thermostat with a Lux Kono thermostat simply to have the ability to run the fan only and circulate the air. I believe this thermostat does that periodically. I'm in ...
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25 views

thermostat issues with honeywell

I've gone thru 3 thermostats in the last 6 months, and the temperature on them goes wacky. I've tried everything except call someone. is there a trick or solution. this is the third honeywell ...
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47 views

Can a Nest work in my setup (or am I stuck with Lyric, as they claim)?

Before crucifying me for the subjective question let me clarify that my question is quite specific if you read on. I bought an old home with bad insulation and a 55-year-old furnace 3 months ago. I ...
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1answer
48 views

Temperature monitoring for storage hot water system (RP-2 connection)

My HWS has a secondary outlet connection I don't use, and I'd like to use it to install a thermal probe I can monitor. HWS RP ¾ / 20 temp probe? Does anyone know of a practical way to install a ...
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1answer
303 views

Connect Wifi Thermostat to Goodman GMP050-3?

I'm trying to connect up a wifi thermostat to Goodman furnace, specifically the GMP050-3. I've done some reading on this but I'm still not quite sure how to go about it. Specifically, I'm not sure ...
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370 views

Nest for this setup

Is this the correct wiring setup for nest.
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578 views

Wiring for a new honeywell thermostat

I am trying to install a basic Honeywell Programmable thermostat, but the wiring is a bit different, and I am reluctant to start taking it apart. I have a Goodman heat pump, which is occasionally ...
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94 views

Identify furance/cooling system from wiring?

Is there any way to tell the heating/cool system you have from the wiring? I have a Honeywell th6320wf02 that was correctly working and then I accidentally overwrote its system type. It's wired like ...
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61 views

Two Separate Systems on one Thermostat?

I have a baseboard hot water system and a separate gas furnace with heat and AC. Thus far, they have been on two separate thermostats. Is there a way to put them on one thermostat or is there a ...
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53 views

Is my control board bad?

I have a Goodman evaporator/gas heating unit that runs the central fan motor constantly after it is powered up a couple of seconds. This happens regardless of what wires are hooked to the control ...
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199 views

Connect C wire to Carrier board

I got Carrier board HK61EA010 and extra C-blue wire that is not connected to the board. I wanna use this wire to power WI-FI thermostat. I cannot find the manual for this board. Does anyone know where ...
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1answer
3k views

Where to connect my “c” wire on the boiler side. Weil mclain gas boiler

Im just curious if the “c” terminal on the plug in relay is where im suppose to connect my “c” wire on the boiler side. I have 18/5 wire ran already. Just need to find out where to terminate. To the ...
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68 views

Furnace and Thermostat Issue

One day my parent's furnace and thermostat stopped working. The thermostat is a smart thermostat that depends on 24volts to the R and C wire. We measured voltage between the R and C wire and was ...
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1answer
3k views

How to wire C wire to the transformer of HVAC?

How are you all doing? I tried to connect the digital thermostat (Ecobee3) instead of my old honeywell thermostat. The original wiring is below (figure 1) HVAC is located on the ceiling of bathroom ...
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412 views

Master thermostats on a multi zone heat system

I have a 5 zone split level house with forced hot water heat. The issue I’m running into is that my house has an in-law apartment that I rent out and it occupies 2 of the 5 zones, and the other 3 are ...
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1answer
315 views

Replacing old thermostat with 2 white wires for zone boiler heat

I am replacing our basement thermostat that had a white and orange wire together and a white and blue wire together. That is all there is. I ham trying to put in a heat only non programmable honeywell ...
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57 views

Thermostat & transformer

I want to ensure I'm safe. Is it normal to find fluctuating 12 volts when the thermostat (2-wire heat-only) is at "rest" and not calling for heat? The thermostat appears to function normally with a ...
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970 views

How to insulate a thermostat

Some previous owner of my home moved the original round 2-wire thermostat to a wall of the vertical chase used for the hot water heater vent, the gas lines, etc. The wall is quite a bit colder than ...
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854 views

Need Help on Adding a Common Wire for Nest

I recently purchased a Nest thermostat. After couple weeks of usage, the Nest is constantly shut down due to low battery. I search online that adding a common wire is the go solution for this. However,...
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1answer
139 views

Ecobee3 lite connected to Lennox Pulse G14Q Heat/Air Condition

I have read a similar wifi thermo connection feed here and they had success hooking the C wire to the T terminal on the furnace. I can get power to run the thermo from the T terminal, but when I do, ...
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1answer
232 views

Ecobee3 Setup and furnace only has W G R

My existing thermostat has 4 wires (missing C) so I'm attempting to use the Power Extender Kit (PEK) at the furnace control board. Only problem is, I only have 3 wires that are obviously labelled at ...
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1k views

Thermostat won't display temperature and won't control heater (although fan works)

I'm having issues with my Honeywell RTH7600D thermostat. It's a couple of years old and has worked fine until recently. We're in Southern California and the cold weather has recently started so I ...
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1answer
69 views

Rapid on/off cycling of furnace

My 50-year old wall furnace keeps cycling on and off as it gets near the set temperature. Can I fix this by changing to a new thermostat? It's a 2-conductor cable (no blower).
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2k views

fireplace thermostat will turn off fireplace but won't turn it on

I have a propane fireplace that wouldn't start. Cleaned the thermopile and thermocouple and got the pilot to work fine. Then the main burner wouldn't light from the thermostat--it only lit if I jumped ...
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1answer
227 views

How to connect wifi thermostat with a boiler after cable upgrade?

I have an old battery operated thermostat right now with two wires (18/2) attached to it running to a boiler. No AC, fan, etc.-- just a boiler. I can easily replace the wire with 18/5 one, however I'm ...
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1answer
79 views

My thermostat and heating system was working fine but the batteries read low power

So my Honeywell non WiFi Thermostat was working fine except for the low battery signal in the top right-hand corner. We took the face off of the thermostat of course shutting the Heat and fan off ...