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Questions tagged [thermostat]

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

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195 views

Nest + opentherm + zone valve

I have a Nest 3G, I'm now considering to change my boiler due to age-related issues. Can someone tell me if I can connect the Heat-Link to both zone-valve (on/off contacts) and boiler (OpenTherm). I ...
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6answers
394 views

Why can I not find a 120V programmable 2-pole thermostat

I'm wanting to connect a 120V wall heater to a programmable, 2-pole thermostat. The difference between 1 vs. 2 poles involves whether or not the thermostat can truly, completely cut power or not. ...
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213 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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2answers
822 views

Can 1 24v transformer support 2 smart thermostats.

I replaced my old thermostat with a lyric. My doorbell transformed was unused and 16 V. I replaced that with a 24 and wired it directly to my lyric. Everything works great. If I do an additional ...
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39 views

how to wire a taco Thermostat to a honey well aquastat with an external 24 volt transformer

How can I wire a Taco Thermostat to a Honeywell Aquastat with an external 24 volt transformer? What wire goes on the T, W, and TV connections in the Aquastat from the Taco valve and from the ...
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69 views

Why won't my air conditioner turn off since a power outage?

Last week the power went out to my neighborhood as they did some work around the corner. When the power came back I found my AC would not turn off. I had the air set to 72 and it went down to 60 ...
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1answer
804 views

Honeywell Mercury Themostat 3 Wire, replace with Digital/Programmable?

Have an old Honeywell thermostat (house is 17 years old). Wondering if I can replace it with a newer Digital or Programmable one? Here are some pictures of it.
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48 views

Smart Thermostat (Nest, Honeywell or Ecobee) from KMC wiring?

I moved into a 1br condo recently and was looking to update the thermostat to Nest (or other Smart home thermostat). The current thermostat model is KMC and when I took off the casing, the wiring does ...
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1answer
181 views

Installing Honeywell RTH9580WF on ICM280 Furnace Control Board

I bought for my new apartment thermostat Honeywell RTH9580WF to replace my old Honeywell TH3110D1008. I watched almost every video I could find on internet "How to do it", but I couldn't fined ...
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2answers
90 views

Is there a low temperature thermostat that is simulatneous switching for two electric garage heaters? [closed]

I want to connect two QMark MUH108 10kw electric garage heaters to a single thermostat. According to the spec sheet, this unit uses 24 V control. It was previously asked about a low temp thermostat ...
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2answers
1k views

Electric baseboard heaters stuck on with digital thermostat

I have two electric baseboard heaters in my house that are both controlled by a single digital programmable thermostat (King ESP-230). I believe each heater is 1500w so 3000w total. Twice now in the ...
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1answer
29 views

Why does my oil furnace cycle quickly?

I have a Rheem ROBF-067LBEA949 oil furnace as part of a forced-air Rheem UPNL-036JAZ heat-pump heating-and-cooling system, controlled by a Honeywell TH5220D1029 thermostat in its 2H1C w/ AUX ...
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2answers
47 views

Upgrading from a 3 wire rotary thermostat to a Electronic Digital

This is my first post so please be gentle. I currently have a Honeywell rotary thermostat (240V) 3 Wires plus earth. Live in Neutral (for the anticipator I believe) Switched live out I appreciate ...
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2answers
737 views

Thermostat set at 65 - Furnace went to 90 - possible causes?

Oil furnace. Honeywell programmable thermostat (not WiFi-battery operated). Heat set as always at 65 degrees F with auto fan. No changes to settings whatsoever. Had been working fine all winter. ...
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2answers
99 views

Why do my rooms heat to different temperatures?

Any advise would be appreciated. We moved into a 30-year-old home and this is our first winter and we've noticed that some of the rooms are colder than the others but none of the rooms are actually ...
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1answer
25 views

Is this thermolimiter faulty?

After recently replacing a broken fan element, my oven still doesn't heat up. I'm trying to establish whether the other elements are at fault or whether the faulty part is the thermolimiter. The oven ...
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1answer
159 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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2answers
31 views

Home thermostat woes

I tried to switch to a new smart thermostat in my home. When I was adding it, something happened. The new thermostat didn't show any power (And yes, the C wire was plugged in). Not knowing what else ...
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1answer
43 views

How can I install a Honeywell Wifi RTH6580WF1001 thermostat in place of a Honeywell RTH2300b?

I have separate heating (hot water) and air handler (cooling System). The current thermostat I'm using is a Honeywell RTH2300B and the new one I want to install is a Honeywell Wifi RTH6580WF1001. The ...
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2answers
2k views

Installing Nest 3rd generation thermostat from Old Trane Weathertron Thermostat (Mercury one)

Nest is not detecting Power (Rh) Showing error that power is not connected. Please help. Installing Nest 3rd generation thermostat from Old Trane Weathertron Thermostat (Mercury one) New stat wiring:...
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37 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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1answer
2k views

Heater will not shut off when it reaches desired temperature

I am just noticing this running the heat. If I set the thermostat to 70 it will run and run and the temperature reads 70 but the unit does not shut off. If I turn it up to 72 and then when it reaches ...
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1answer
50 views

Is a 4000W line voltage thermostat sufficient here?

I want to upgrade a baseboard electric thermostat to a programmable. The existing digital, non-programmable thermostat is rated for 22A (5280W) (made by PSG). The only programmables I can find max out ...
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1answer
30 views

Can a Thermostat Common Wire (C-Wire) Be Added to a DNV40NB Heater?

During recent renovations, we had to move our existing thermostat. Instead of replacing it with the same dumb 2-wire knob (white/red), I'd like to get a smart thermostat like the ecobee3. All of these ...
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545 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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3answers
83 views

Thermostatic Control of Simple Apartment Heater

My daughter's apartment has a very simple heater. As shown in the pictures below, it is an heater-coil unit with only a fan control. There is no temperature control or thermostatic feedback. So, for ...
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0answers
3k views

Honeywell RTH6500 WiFi Thermostat wiring questions for a heat pump

I'm trying to install a new Honeywell RTH6500 thermostat on an old heat pump system that has regular plus emergency heat and the closest matching diagram says to put both the white "W2" wire and black ...
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2answers
212 views

Box Fill for Line Voltage Thermostat

I know that normally a receptacle or device in the gang box counts as 2 conductor volumes. Does a line voltage thermostat just count the same as any other device? I'm replacing an old mechanical 240V ...
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1answer
55 views

Fuel oil burner running intermittently

Fuel oil (Beckett oil burner) here. It's -20°F outside right now and the house is at 61°F even though I have the thermostat cranked up to 75°F (we have a thermometer in the house as well, ...
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2answers
49 views

Help with Sain Smart 24V Relay Cycle Timer Module

I'm considering getting one of these: https://www.sainsmart.com/products/24v-relay-cycle-timer-module ...to force my 2nd floor thermostat to force heat on every so often (say, 1 minute every 15) to "...
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722 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
90 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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2answers
153 views

Why would furnace not come on immediately?

I had a brief scare just now. It is 7-degrees right now and getting colder so I definitely don't want a furnace failure. I came home and house was at 62 with thermostat at 64 (my standard not-at-home ...
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1answer
148 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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1answer
656 views

How often to replace thermostatic mixing valve

To start off, I absolutely hate idea behind thermostatic mixing valve, but that's not a question. The water in my house runs hot for about 10 minutes and then turns icy cold, and I have to turn it ...
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3answers
250 views

Why is the furnace heating the house far past the thermostat setting

Problem: Furnace came on as usual in the morning but failed to shut off after the set temp on the thermostat was reached. The house temp (as measured on the thermostat) reached about 10 degrees higher ...
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2answers
88 views

Upgrading baseboard thermostat -wiring help

Going from old analog thermostats to programmable digital. They're all 240v but appear to currently be wired as single pole and new stats are double. Photos attached of line in, and two out for load- ...
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1answer
278 views

Upgrading 2-wire to Ecebee3

I have a honeywell 2 wire thermostat (old) that has 2 wires R W that seem to be wired directly to the furnace (blower/burner??) but I also have a control board with no wires attached to it. I tried ...
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1answer
139 views

Adding a C wire to older 3 wire

How do I use the green wire as a C wire as suggested in most installation instructions for the newer wi-fi thermostats? They all reference terminal strips at the furnace, all I have is the 3 wire ...
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0answers
185 views

modine heater connection to honeywell thermostat

I have a 45k modine heater I just installed and want to attach a Honeywell RTH6580wifi thermostat to it. has anyone done this and what wires do I connect to what wires.....heater and thermostat. ...
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0answers
181 views

Five stages of heating and cooling on the nest thermostat

Third generation nest thermostat base I have a boiler for in floor radiant heat and two stage heating and 2 stage AC forced air unit. I would like the GEN three nest to control both units using the ...
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0answers
610 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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2answers
842 views

Can I use the Y wire in place of the C wire for my new thermostat?

I'm looking to wire a Honeywell Lyric T5 to my furnace (I do not have an air conditioner, I do have a humidistat). My current wiring at the thermostat is G,W,Y,R. At the furnace it's G,R,C, and 2 at W,...
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1answer
53 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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1answer
1k views

Thermostat won't always start heater on its own

I have a gas furnace that seems to work fine; it keeps the house warm when things are running as expected. Sometimes, however, we'll notice the house is getting cold. The temperature on the ...
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1answer
265 views

Is it Code to support Class 2 (thermostat) wires using a gas line?

Related to this question. Our gas furnace, while quite functional, has some quirks in its installation. One of them is that the installers cut off the old (original to the house) thermostat wires at ...
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0answers
41 views

furnace wont kick in

My furnace seems to work intermittently. overnight its seems to stop... i have checked the thermostat and it shows says it is heating. fan is on auto, but nothing coming out. when i turn heat to off, ...
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2answers
113 views

How to check thermostat is working?

This is the wiring of my Honeywell T8411R. I noticed my room was not warming up. I moved the switch to Em.Heat and still no warm air blowing in ducts. I would like to test if my thermostat is sending ...
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2answers
683 views

Pulling wire using previous wire?

I’m trying to pull a new thermostat wire down from a first floor room down into the basement. The exit point in the basement is in the ceiling, between two ceiling boards pretty inaccessible. Would it ...
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0answers
1k 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 ...