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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390 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 wire this old Lennox thermostat to my Heil 2003 furnace?

Here is my attempt which isn't working. Maybe I should jumper R to G and move the green wire to C with Blue? The wires I cut off it had that jumpered. Here is the image address: https://imgur.com/...
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6answers
22k views

Which furnace thermostats support variable swing/deadband?

My home furnace is currently controlled by a programmable Honeywell thermostat, but it regularly thrashes the furnace by turning the furnace on for just ten or twenty seconds. It seems that the ...
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Where do I connect my C wire from my thermostat when there are two transformers?

I have a Laars gas boiler that has 3 heating zones. I want to replace the old mercury honeywell tstat on the 1st floor (heat only) with a newer honeywell RTH9580 wifi model. I've taken pictures of my ...
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987 views

How can I add a C-wire to a Venstar T5800 thermostat?

I am trying to replace my existing thermostat. My old thermostat has: Rh, W (coming from the heating unit). Rc, Y, G (coming from the AC unit). On the Venstar T5800, I can map as follows: Rh+Rc -...
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Trane air handler twe036c140a0 create “c” wire

Trane Air Handler twe036c140a0 Create "C" Wire Can someone please tell me the best way to Create a "C" Wire for a Honeywell WiFi thermostat (model rth9585wf).
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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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Honeywell Home Thermostat - wiring issues?

I have the Honeywell Home - 7-Day Programmable Thermostat. When my roommate installed the device it was winter and everything appeared to work fine. Now that it’s heating up, it’s impossible to cool ...
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4k views

Nest thermostat - combi boiler and UFH set up question

We recently had some work done, a new open plan room, a new boiler and underfloor heating (UFH) put in. We had some confusion, a lot of which comes from not having a basic understanding of how the ...
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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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159 views

Why is Thermostat Y wire connected to C terminal on furnace?

I have a Nest E thermostat, and like many others have lost wifi and getting low battery because I have no common wire connected. After looking at my old Lennnox 78ugf3-75-1 furnace, I noticed that my ...
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340 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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Adding c wire to Goodman model GMT070-3B gas

this is a photo of the old board I took out a while back. New one is the same. I'm trying to add a c wire and don't know where to put it on the board. Can anyone help me?
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69 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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55 views

Unconventional thermostat wire labels on boiler

I have inherited an electric boiler for heating water in pipes running through the house. The existing thermostat is a very old and very simple mechanical one. I want to install a more recent ...
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1answer
474 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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649 views

Thermostat C Wire (Possibly Unconnected)

I purchased a Honeywell RTH6500 Wifi Thermostat, which requires a C wire. My old thermostat showed a connected blue C wire. However, it was battery-powered. If I removed the battery, the thermostat ...
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92 views

Using a second thermostat as a remote temp sensor

I’m using Honeywell WiFi enabled thermostats to control heating and cooling at home and cottage. I would like to add another thermostat of the same type simply so that I can remotely read the ...
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1answer
518 views

Installing a Hive Thermostat

I purchased a HIVE thermostat and want some assurance before I go about installing this. First of all i was wondering where to put the receiver as I thought it would just replace one of the ...
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1answer
584 views

New Thermostat installed but compressor comes on immediately

I have a new Insteon Thermostat that I'm using to replace my prior Honeywell t-stat. This is installed to a relatively new HVAC system (both AC and Heat) that DOES have a "c" wire. I've attached the ...
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2answers
33 views

Trouble with identifying wiring for heat pump setting up Nest

The home I moved into has a Honeywell thermostat controlling an Amana heat pump. I am trying to replace this with a Nest thermostat instead. Here is a photo of the wiring for the existing thermostat ...
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1answer
154 views

Another “How do I add ”c" wire to boiler for Nest

I have tried searching this forum and others, but I could not find anyone with a situation like mine. I thought it better to ask here, rather than damage something. I have a Lennox wall mounted ...
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24 views

Question About Wiring - Hooking up New Thermostat

Replacing this: src With this Honeywell Mable thermostat. Regarding the wiring, it doesn't exactly match up, can someone help clarify how to wire the the thermostat? The old wires are hooked up ...
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2answers
109 views

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
75 views

Connecting Common Wire to Control Board

I have a heat pump and want to add a thermostat that requires a common wire. I have read through many threads that show how to add a wire but I already have a few extra in the bundle so its not so ...
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1answer
34 views

Can’t shut off power to heat-only (hydronic baseboard) thermostat

I have no AC in my condo, only hydronic baseboard heat, currently controlled by an old mercury thermostat. I have a new smart thermostat with a c-wire adapter I want to replace it. Trouble is, I’ve ...
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179 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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65 views

Plz help me, connect a common wire for smart thermostat in furnace

I bought a 3rd generation Nest. It doesn’t turn on after I hooked it up. I did research saying I need a common wire as power supply. I have closely look all the wires in my system and drew a diagram....
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33 views

Replace existing swamp cooler thermostat with smart thermostat - any special differences between the two thermostat types in this application? [duplicate]

Has anyone replaced their swamp / evaporative cooler's existing thermostat with a smart WiFi-connected thermostat like Nest or Ecobee? I want to know if there are any differences in connection or ...
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1answer
35 views

How can I control my furnace fan from a secondary thermostat?

I have a WaterFurnace geothermal system with upper and lower level zones. I recently added an outdoor wood burner and my issue is that I want to use a secondary stat to run the furnace fan during the ...
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29 views

No Y wire to thermostat

I am trying to install a Honeywell rth6580wf thermostat. I have located all the wires except Y. It is a gas powered heat and central AC system. At the system there is a Y wire going outside to unit, ...
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4answers
6k views

How to wire a relay for an evaporative cooler to a thermostat?

I have an evaporative cooler with 120VAC control that I want to switch on and off using a relay that is activated when the cool call comes from my thermostat. I plan on just using 1 relay to activate ...
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447 views

Why might a central heating programmer no longer override a room thermostat?

My central heating and hot water is governed by a Danfoss FP715 Si. Using this I can set the time each day when the central heating and the hot water come on and off. When the central heating is on it ...
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1answer
513 views

Figuring out electrical connections for THREE electric baseboard heaters with single pole thermostats

I recently purchased a home (triplex) and in the basement unit, which is a one bedroom apartment, there are three baseboard heaters (bedroom, washroom, and living room). The issue is that the living ...
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2answers
279 views

Lennox G23Q3/4-100-2 And Ecobee4

**Pictures attached to go along with my rambling explanation I have my Lennox G23Q3/4-100-2 natural gas furnace and my central air system that has been working since 1995 on a basic programmable ...
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4answers
70 views

Thermostatic control of an unmanaged energy source to supply hot water cylinder

I have a solid wood burner that contains a heat exchanger. There is no guarantee that the combustion can be regulated. This heat exchanger feeds a loop that acts as the source heat exchanger in a hot ...
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1answer
126 views

Honeywell T6 PRO Z-Wave Thermostat (model th6320zw2003) exhibits very erratic behavior after battery replacement

Background: My apartment complex installed Honeywell model th6320zw2003 thermostats in all units about six months or so ago, and it had been working well for all that time. The only issue was that ...
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909 views

How to connect c-wire to Burnham Series 2 boiler?

I am trying to install my ecobee 3 light but the previous thermostat did not use any c wire. Fortunately, there was an unused wire in the wall and I would like to set it up as a c-wire. The problem is ...
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1answer
52 views

replace fireplace switch with nest thermostat

I have a fireplace wired up to a switch (simple off/on), and I want to throw a Nest thermostat on there. It has a black and white wire coming out of the wall. I think the white goes to the W1 and ...
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78 views

Nest thermostat e heat link replacing the old danfoss

I really need help with replacing this current danfoss thermostat with a new nest thermostat e heat hub. I'm in the UK. Below is the new heatlink just need to know what wires I need to wire and what ...
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1answer
57 views

Checking my understanding - How to add C-wires for smart thermostat install x3

I'm in the process of installing some smart thermostats (Nest Thermostat E) to replace my old ones. I have a boiler radiator heating system with three zones. Two zones are straightforward heat only (...
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53 views

Replacing A Trane thermostat with A Honeywell Wifi thermostat?

Heres what I have. On A Trane brand thermostat Red wire = R Black wire = W2 White wire = W1 yellow wire = Y Green wire = G Orange wire = O Blue wire = B or from what i'm told is my C wire?? And i'm ...
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1answer
96 views

Do I need a special thermostat to take advantage of a modulating gas valve?

I just got a high efficiency condensing gas furnace installed. I feel like it was done poorly, but I'm not sure. Some questions I'm wondering about are: Do furnaces need to be level? It is visibly ...
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34 views

Intermittent Furnace Issue

So I have been having a bit of an issue with my furnace since installing the nest thermostat. The first day after I installed it was perfect. Everything was working. The second day I kept getting the ...
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1answer
2k views

Add a c-wire to 25+ year old Rheem furnace

I've looked at just about every post on adding a C-wire to power a WiFi thermostat but remain uncertain on how to proceed. The current installation on a Rheem RGAC-080A is two wire as here: XFMR - ...
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1answer
1k views

How do I get the Nest Thermostat to warm up my house prior to arrival

I have a Nest Thermostat and live in the UK. I have a radiator based heating system. When I leave the house, some time later the Nest realises this and sets my house to Away. From this point onwards ...
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1answer
8k 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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2answers
34 views

Is a 2.5 Ampere relay sufficient for 24V thermostat AC only application?

The goal is to 24V control signal YEL (cooling) and GRN (fan) for a Florida storage building, with three AC units. A single board computer (Raspberry Pi) is outfitted with 2.5 Ampere relays. Is ...
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1answer
46 views

No C terminal on furnace. Workarounds? Possible the AC?

I'm Trying to connect my C wire to install a new thermostat but the furnace doesn't have a C terminal. In my readings on this I found that because I have an AC,I can connect my C to one of the wires ...
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11 views

I have a Quadra-fire topaz direct vent gas fireplace, what type thermostat is needed

I'm looking to run a thermostat to my gas fireplace, it's a millivolt system, how do I wire the thermostat correctly

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