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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Missing c wire for new thermostat

Tying to install new smart thermostat but no c wire available. Was going to use g wire in c terminal but noticed the the g wire( old thermostat) is green and when I checked furnace,that green wire is ...
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Where to add C wire?

Would anyone be able to tell me which group of wires I add the C wire too?. I think it’s the white one but want to make sure Thank You
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Smart Thermostat - C Wire

I'm about to go out and buy a smart thermostat for my place and had a question about the 'c' wire (common wire). From what I've read online, the blue wire is commonly known to be the c wire for the ...
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How to fix/calibrate mechanical thermostat that sometimes won't turn on heater?

In my house I have mechanical thermostats that control wall-mounted electric heaters. I have a couple of problems with these thermostats: Sometimes they won't turn the heater on at all. Even if I put ...
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AC blowing hot air

I have been remodeling a small building for the last 6 months or so. We had power disconnected to this building since April. We just barely got the power back on, and after some work were able to get ...
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Marley hydronic baseboard heater help

I’ve installed my double post thermostat. The white wires are hot so each is capped and tucked individually. The power source to the heater is connected to the top wire and bottom wire (which is ...
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Adding a C wire to Nest learning thermostat 3rd gen

I'm trying to add a C wire to my Nest thermostat, I already had the C cable on both ends but it wasn't connected, I went to the attic and connected the blue wire from the thermostat wiring to the C ...
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Adjust Multi-Speed Carrier Furnace via thermostat as in manual, or need to rewire?

I have a Carrier 59SC2C100S211120 furnace. The blower is pretty loud and everyone says they really feel it when it comes on. I would like to turn down the blower in normal operation and then, if also ...
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Oven thermostat substitute?

I own an oven that uses a 2168 thermostat pictured here: with a wiring diagram that looks like the one on the right: . For reasons that I can't determine (mercury?), this thermostat is very hard or ...
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HVAC Thermostat not powering on, blown transformer?

We have recently been having some remodeling done at a currently not-occupied home. One of the things done was a brand new breaker was installed. Before the breaker was installed, our HVAC was working,...
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I'm installing a nest thermostat. The wires at the base are R G Y W

On my 24v transformer there is a C POST. I have wired the nest thermostat with the 4 wires R Y W G. Nest says the termostat needs a c wire,Can I just run a wire from the C post on the transformer to ...
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Turning HVAC on/off using the circuit breaker

So my thermostat is fried. Had a very capable HVAC technician take a look at it and he found this out. I have ordered a new one but it isn't going to be here for the next 2-3 days. I live in Texas and ...
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Heat Pump Condensate Safety Switch Wiring Question

I recently purchased a simple condensate overflow safety switch (Rectorseal 97647) to install in my attic air handler unit. I currently have the switch installed on the red wire, but do notice the ...
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Furnace/thermostat wiring confusion

[We purchased a house last year and I am just now getting around to this. We are wanting to exchange our non programmable thermostat T6-NHP01-A to a programmable one (we have a nest). I have changed ...
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Help on Wifi Thermostat Wiring Guide

I do have the WiFi thermostat (picture attached) that I m trying to attached with my current central airconditioning unit but no success after trying multiple wiring. I does have three wires coming to ...
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Can you install a heat pump with 4 wires?

I currently have a central AC system. I'm looking into replacing it with a variable speed one. I've been told that if I'm replacing it anyways, I should look into getting a heat pump instead for a ...
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What would cause the fan setting on my thermostat not to turn on the air handler fan

Just recently the fan setting on my Honeywell RTH8500D doesn't turn on the air handler. This is a recent problem. I usually run the air handler 24/7 during "pollen season" to filter the ...
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New thermostat not compatible?

I have a new Honeywell thermostat that says it is compatible with oil furnaces, but I just took off the old rotary one and it appears there are only two black wires. I assume this will not work, ...
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replace fossil-fuel kit on dual-fuel heat pump with upgraded thermostat

I have a 25-year old dual-fuel heat pump (about which I've asked many questions here). There is a PCB in the furnace/air-handler called a "fossil-fuel kit" that handles switching between ...
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1 answer
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No voltage on old thermostat wiring

I'm trying to add an amazon smart thermostat. I don't have a C wire, but there is a spare black wire behind the thermostat. I put my multimeter on 200 VAC and expected to see 24 VAC on the red wire. I'...
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240 volt to 120 volt plug from HVAC blower motor

I am trying to place both germicidal lamps (approx 70 watts total) and a negative ion generator in my air condition return space where the blower motor is. My fist advice was to run these two devices ...
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why does my air conditioner run when at set point

my 10 year old a/c now starts even though house is at set point. if I raise set point it will shut down. all day long with set point at 79 it will start, run and shut down again with ambient temp ...
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C-Wire Adapter without Y wire on board

I was looking to get our AC thermostat replaced with a smart one. We have an outside unit, upper unit, and the thermostat. I checked it out and no surprise, there was no C-Wire in use or hidden ...
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What should connect to the COM contact on my new thermostat?

I am replacing a fan-coil thermostat. Unit itself is Wito ultra-s 06-2t. Old one was wired and installed by an electrician, quite some time ago. I dismounted the old one and wanted to replace it with ...
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Can it happen that with a high hot water output in an electric dual flip-flop thermostat heater the lower thermostat is never turned on?

We have a problem with an electric dual element heater with flip-flop thermostats (only upper element working). The plumber changed both thermostats once, the heater failed again in the same way, and ...
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Electric Wall Thermostat with Remote Option

I have a an apartment from 1980s, so the thermostats are quite old. One of them is Marley MD26 Qmark Electric Line Voltage Wall Thermostat x 3. Plus 2x thermostats that built into the heaters ...
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How do I wire this Sensi touch smart thermometer with my old radiator furnace wiring? No panel

Four wires coming out of the wall to the old thermostat are W,G, R,Y. There is no extra wire to use as c wire, so I decided to go the route of the “use g wire as c wire” since I don’t care about ...
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Dryer won't heat even after replacing the Thermal Fuse, Thermal Cutoff Fuse, Thermostat Cutoff Kit, Heating Element, Thermistor, high-limit thermostat

Dryer won't heat. Heating element wont hold continuity. Ordered a New one, got the wrong part, took the coils off the new heating element and put them on old.. installed.. this worked well for 5 min ...
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Home electric panel: Two different electric cirtcuits on the same thermostat

Trying to figure out if the electric installation is up to code at my place. There are two electric circuits : The first one feeds the electric heaters in the living room The second one feeds the ...
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1 answer
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Advice on how to wire a 4 wire RGWY wifi thermostat to an old hvac with no c wire?

I have a 4 wire RGWY coming out of the wall to my old thermostat with no additional wire available for c wire. I was going to use the green one instead as I saw a tutorial online, but when I got to ...
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Where do I connect my common wire (C wire) for smart thermostat?

I've been running 2 Nest thermostats (1 upstairs, 1 downstairs) for years that didn't require a common wire. I'm replacing them now with Ecobee3 Lite thermostats. Both thermostats control heat from ...
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How can I tell if my current thermostat wiring has a C wire?

We just moved into a new house and I want to replace the thermostat. I am trying to figure out if my current setup has a C Wire. If it doesn't, then I'll need to get a new wire run -- which I want to ...
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Where to connect the C Wire? See pictures and diagram [duplicate]

I have Rheem RBHC-14A00NFA AC unit. I am trying to install nest thermostat but don’t know where to connect the C wire. I am attaching the picture of the wires and the diagram. Please help! Thanks
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Nest Installation Wiring [duplicate]

Hello trying to wire a Google Nest Learning Thermostat and my old one used only VG and V+ and now I need to know what I should hook it to.Also I have 3 others wires that weren't hooked to anything in ...
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How are these 2 Water Source Heat Pump units wired to a single Thermostat?

This is a brand new construction, 13 floor apartment building in Manhattan. I am trying to replace the stock thermostats with the new Ecobee. 3 rooms were easy but the larger living area has 2 of ...
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How do I properly wire new Honeywell thermostat?

I’m writing because I’m trying to replace my old Honeywell Thermostat with a new one. The old labels for the wires does not match what they are asking for with the new one. I’ve attached a pic of the ...
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Wiring of a Vine TJ225 thermostat

How do i wire a TJ225 Vine thermostat? I have 2 red wires, a green, a white, and a blue wire. Red wires go to RH, and R, G goes to green, white to white, and the blue goes to Y on the old thermostat, ...
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Help with installing Google Nest thermostat

I have a Google Nest I want to install and I saw there was an unhooked blue wire at both ends, so no big deal right? Wrong, apparently. What the heck? We have a Climatrol 170-1-080-02-00 furnace and a ...
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Would a smart thermostat be effective for a floor with the thermostat always off?

I installed a smart thermostat on my 2nd floor since I ended up tweaking it often to reduce my electricity bill. I left the 1st floor as a dumb thermostat since I've always left it off. My upstairs ...
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No C wire for Nest thermostat but unused C terminal on furnace

I know this question is similar to others I’m just hoping for a short answer. It’s a small house and the thermostat and furnace might be twenty feet apart. The control board on the furnace has an ...
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Goodman AH2429-1A

I am trying to convert my old thermostat to a Wyze smart one and everything was going smoothly until I tried to connect the c wire adapter. I can’t find the terminals labeled YRGW like it wants me to. ...
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Does the NEC recommend metal or plastic boxes for 240V? [closed]

I need to install a junction box for 240V going to two separate Thermostats for baseboard heaters (one 750W and another 1100W). Should I use plastic or metal boxes for the thermostats and junction box?...
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1 answer
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Existing thermostat wire colors - no white?

Looking to switch from an old Honeywell CT87A thermostat to a smart thermostat, probably something requiring a common wire. There are 2 thermostats (one on each floor) in a 2 zone forced hot water oil ...
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What smart thermostat can be used for this gas heater?

I am located in eastern Europe and smart thermostats aren't a thing here. So there are no people with experience in installing these. I really would love to use something like google nest or ecobee ...
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Ecobee 3 Lite / Fan Center for Fan Coil / Aquastat

I live in an ancient (1967) condo with a two-pipe system. Cold supply in the summer, hot supply in the winter. There is no electronic changeover or even an automatic cutoff valve. The radiator coil ...
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Can I split a single 2500 watt baseboard heater into 2 smaller heaters?

I am converting a large bedroom into 2 smaller rooms by adding a dividing wall and hallway (see diagram). The large room had a 2500 Watt electric baseboard heater (240V). I would like to use that same ...
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Why does my furnace blower turn on when the thermostat is turned off?

The weather has been nice so we have had our thermostat turned off for about a month. The other night it turned on randomly and started blowing warmer to hot air getting the temperature to 78 degrees ...
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Lennox Wiring for Ecobee SmartThermostat

Confused by the wiring, hope someone can help me out. At the furnace there's only four wires in the cable (R, B, G, and W), but at the other end, a yellow wire appears. It's not reflected in the ...
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Is it possible that Thermostat Y wire and C wire is the same wire on my air handler (furnace)?

I'm trying to install Ecobee, and like many others, I do not have C wire at the thermostat, thus need to find it on my air handler. My air handler is from Allstyle and the model number is HFD36-42840G-...
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Nest C-wire issues with old boiler, xfmr, and 8124 aquastat

I have my C & Rc connected to my old 28vac xfmr and my W & Rh directly to T & T on aquastat. I added the Rc so the Nest would stay active in Summer when boiler is turned off. This setup ...
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