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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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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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40 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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Need C wire for Nest thermostat with zones. From zone panel to thermostats?

If I have a C wire connected from the furnace to the zone panel (but not to the thermostats), do I only need to run new C wires from the zone panel to the thermostats?
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1answer
31 views

nest 2nd gen, no common wire/terminal in the fan coil unit

I'm trying to install an older nest in my condo but it immediately complains that there's no common wire attached (error e24). I opened up the fan coil in my condo and there is no specific terminal ...
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1answer
66 views

What powers a Nest thermostat? [duplicate]

I have an older thermostat I'd like to replace with the more modern Nest thermostat. The online Nest compatibility checker tells me that I have a compatible device. However, I'm not sure how it could ...
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1answer
31 views

Install Hive Thermostat - C wire power

I am installing a Hive Active thermostat. My previous thermostat was battery operated and did not use a C wire. However, I found a 5th, blue wire, behind the thermostat so I used that as the C wire ...
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27 views

thermostat does not accept C wire connected to AC unit

I have three identical thermostats, model Radio Thermostat CT101. Two of them have C wires connected to the burner and work fine. The third one controls a heating zone and also central AC. It has R ...
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1answer
43 views

Will my wiring setup work with the Nest Thermostat?

I would like someone who is smarter then me to let me know if this current wiring setup would work with the Nest Thermostat? Thank you for your help
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1answer
59 views

How do I create a C wire? [duplicate]

My furnace is old and only has 4 wire connections, but I require a C wire. How can I create one based on this diagram? I do have 5 wires running between the furnace and thermostat.
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1answer
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Honeywell thermostat issue

I have a Honeywell thermostat with M-F schedule like so... 6:30 am (wake) - 70 6:45 am (leave) - 63 4:00 pm (return) - 70 9:00 pm (sleep) - 63 The Honeywell actually displays wake, leave, return, ...
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How can I use home automation with hot water heating radiators?

My apartment (in a condo building) is currently using stationary PTACs (using electricity and hot water), which I'm planning to replace with a split-level A/C system (for cooling) and hot water ...
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1answer
99 views

nest 3rd generation compatibility with honeywell

My home has a honeywell thermostat (THM5421C)! It has 3 wire: DATA,R and C. Humidifier is Aprilaire 700 Series and Furance is Armstrong A97USMV! furnace side: The wire connection as below: Is it ...
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Will a Gledhill Boilermate 2000 work with a Honeywell Evohome thermostat?

Our flat uses a communal CHP system, with a Gledhill Boilermate 2000 in our flat (i.e. we don't have direct access to a gas boiler). We're looking to set up a Honeywell Evohome system consisting of a ...
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2answers
68 views

Electric Baseboard Heater Thermostat Replacement

My house is mostly steam heat, but prior owners put on a small addition and also turned an upstairs closet into a bathroom. These new rooms have electric baseboard heat. Heaters work fine, but ...
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1answer
31 views

thermostat connections with different size wires

my current thermostat has 14 gauge wires connected to it and the wires are supplying 24 volts to the thermostat. i want to get a new thermostat but will need 18 gauge wires. since the voltage from the ...
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1answer
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Why is my thermostat turning the heat on too soon?

I have recently come across an issue with my thermostat and when and how my heat comes on. My thermostat seems to be an old round Honeywell. I set my temp at 65 typically. As of last night my ...
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56 views

Ecobee Smart Thermostat- Using Room Sensor as primary control

This is ultimately a fairly simple question about the Ecobee3 thermostat and the wireless room sensor functionality, but I'll explain my situation first. Twin home, 2 stories + finished below grade ...
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2answers
48 views

control for attic fan

I have an attic fan with an old (MH Rhodes 90015 /marktime) mechanical timer switch. I want to replace the timer with a thermostat (presumably a line-voltage thermostat). To my surprise, in the ...
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1answer
52 views

Replace existing thermostat with diy solution [closed]

I currently have a wireless Altech thermostat. Is there any chance I can replace it with an diy solution (based for instance on a Raspberry Pi)? The idea will be to only replace the transmitter and ...
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1answer
57 views

Can’t turn off power to thermostat

I’m installing a nest thermostat and trying to turn off power to the thermostat before doing so. I’m using a voltage tester and can see the wires coming in have power. I have two systems, one for ...
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1answer
103 views

Old Thermostat with just R and Y wires?

UPDATE: this may be R and V, not R and Y, although I'm still not sure how it was set up. I am replacing an old thermostat in my house (the house is from the 60s, I'm not sure how old the thermostat ...
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How to Run Fan Only with Thermostar Furnace With G Wire

I have a Thermostar Furnace that works great for Heating our home. We do not have AC and do not want that. But, we do want to be able to just run the fan without heat. The W and RH wires were ...
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Thermostat White-Rodgers 1F82-261 switches to stage 2 heat for no apparent reason

I am running a central heat system that uses a heat pump as stage 1 and a gas furnace as stage 2. The thermostat used is the White-Rodgers 1F82-261 which supports 2 stages of heat. When using regular ...
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1answer
117 views

Where is the C wire terminal on my boiler

I am trying to connect the T5+ smart thermostat to my oil based furnace. I see there are only two used wires at the thermostat R And W but 3 additional cores available. My boiler is a old Weil McLain ...
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2answers
74 views

Can I reverse my heating zone?

I have a three zone hot water boiler based heating system. The boiler is currently at one end of my ranch style house. The radiators appear to be directionless (no valves or anything). One of the ...
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1answer
89 views

How should the thermostat wires be connected to my furnace?

I have an Amana AMV90704CXBB furnace, and regular programmable thermostat. I took the furnace apart because I have to wash the blower motor wheel. It was covered in construction dust. In order to ...
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92 views

Where should I connect my C wire on Goodman GMP075-3 Rev.B

I am trying to install an ecobee4 to replace a digital battery powered thermostat. I removed the existing thermostat and found that there was a spare blue wire that was wrapped around the others that ...
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1answer
34 views

Finding Common Wire on Laars JVT boiler

Replacing mercury thermostat with wifi. I have just a red and white wire connected to current thermostat and boiler. There is a green present, but it isn't hooked to anything on boiler. So I can ...
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3answers
145 views

Making sure old Honeywell Thermostat (round dial) doesn't turn on

I've had to cover my baseboard heater with painter's tape and duct tape because I keep getting click beetles strolling into my apartment after 6pm (I live in Michigan, and the temps are dropping). I ...
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0answers
313 views

How to wire a Taco zone valve controller with ecobee

I'm having an issue with wiring my Weil McLain gas boiler. It was wired up fine and working for a single zone. I added (2) 4 wire zone valves in. So I now have 2 zones, a Taco zone valve controller(...
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1answer
23 views

re-wiring/retro-wiring a Carrier 40MVC024 ductless A/C for external thermostat: guidance

My server room has two air-conditioning units, with acutely counterproductive controls. I want to rewire them for external thermostats. Can I simply splice a traditional thermostat inline with the "...
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Do I need to replace the thermostat wiring leading to my boiler?

I have a boiler in an old building with four different apartments. There are two thermostats that call for heat from the boiler, and valves that direct the hot water to the respective part of the ...
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1answer
453 views

Why my baseboard heater won’t turn with new thermostat?

I have a pair of electromod basement heater. The label on each of them show them show 750/1000W. Power supply to this is 240V I am trying to replace the old manual thermostat with a progrmabale one. ...
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1answer
38 views

Upgrading from a two wire analog tstat to a Nest, need help

I am looking to upgrade from an old analog tstat to a Nest. My old stat had only two wires connected (R and W) but the wire bundle had three. So I tried connecting the green wire to C and then turned ...
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1answer
58 views

how to get 240V to 4 wire 240V thermostat

I have a 2 pole circuit breaker in the panel with a 2/12 cable connected to it. Black wire is connected to one pole, white wire is connected to other pole and bare wire is connected to ground bar. ...
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3answers
398 views

Wiring for ecobee3 lite

I recently purchased the ecobee3 lite and am now stuck trying to install them. I have 3 Honeywell thermostats I am looking to replace and my heating system is oil/hot water. My home was built in 1970 ...
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2answers
104 views

Checking voltmeter on my Honeywell Wifi Programmable Thermostat

I have a wifi programmable Honeywell thermostat. Worked fine for 3 years, this morning I turned on my gas furnace for the first time this year and it would not go off, even when I set the "Heat" / "...
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1answer
57 views

replacing old line voltage thermostat

My old 4 wire 240V mechanical line voltage thermostat stopped working. I want to replace it with a digital thermostat. Problem is I don't know the amp rating of the old thermostat. I checked with ...
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1answer
97 views

Wiring Baystat240a to Honeywell RTH2510 w/ picture

I tried to hook up the wires but all the lettered terminals on my old thermostat don't match the letters on the Honeywell thermostat. I have the AC working but I still have three wires left over. I'm ...
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1answer
183 views

Connecting Wood/Electric Furnace to Smart Thermostat

UPDATE: I spoke with an ecobee tech and they pointed me to an alternative solution. If I get an adapter called a "Fast-Stat Common Maker", all I need to do is figure out where to connect the C-Wire ...
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1answer
967 views

How do you remove a Carrier / Bryant Infinity thermostat control from the wall?

I have a Carrier Infinity system with model # SYSTXCCUID01-V thermostat/control. I need to temporarily remove it from the wall. I found a diagram of how to install it: (diagram source) I do not ...
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1answer
69 views

Ecobee 3 lite Installation — Confusion about C wire (on furnace but not at thuermostat)

I am about to install the ecobee 3 lite thermostat. On the thermostat end, there is no C wire - just the typical 4 wires - R,Y,W,... On the furnace end though, there is white C wire too, which I do ...
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2answers
144 views

How to hook up new 5 wire HVAC cable to newer HVAC unit with only 2 wires coming from it?? WITH PHOTOS

I have a newer HVAC unit that was installed using only 2 wires to control the heating only on the unit. The unit is capable of having AC connected and I would like to wire it so that it will work with ...
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0answers
24 views

Troubleshooting remote AC (heat pump)

BACKGROUND The system was working well in July: 6AM: AC turns on and reaches target temperature of 77 deg ISSUES Although it is a heatpump in cooling mode, I will refer to the system as an AC for ...
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1answer
53 views

My AC and Heat systems are separate, Can I wire one or both fan(only) controls to my thermostat?

My house used to have just Forced Air heat, but a year and a half ago, I had central air installed. When it was installed I had questions about the wiring they weren't addressed to my satisfaction. ...
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1answer
326 views

Turning off Power to Thermostat to Replace It

I'm replacing my old thermostat due to issues with it somehow not staying at my set temperature. It's a Simple Comfort 2001, and I'm replacing it with a newer model, a Simple Clean 2001L. Both of them ...
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1answer
37 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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0answers
36 views

smartzone or Furnace: c-wire to smart Thermostat

I'm about to add the c-wire to smart Thermostats. However, I'm not sure where to connect it as I have the following options: I have two zones, ( and I have two smart Thermostat) , I can connect the c-...
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2answers
96 views

Need to identify a common wire on my old HVAC

For Nest Thermostat 3, I am trying to identify a common wire on my old HVAC. The diagram can be found on the link below:
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2answers
780 views

Where do I connect a C wire in an old Furnace?

I am hoping to be able to upgrade to a smart thermostat but unfortunately my furnace doesn't have the "easy" option with an obvious C terminal. My furnace is OLD but it actually has the full 5 ...