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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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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wiring hrv in a confusing house

some beautiful pictures first time posting apologies if my placement is off Buying HRV. I am debating between two units, venmar evo5-700 which doesn’t support furnace interlock or lifebreath rnc205, ...
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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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24 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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Replace existing swamp cooler thermostat with smart thermostat - any special differences between the two thermostat types in this application?

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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68 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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43 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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45 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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36 views

How do I wire a/c if furnace wiring compartment has no y terminal? Have not found anybody that knows -Help?

I have been trying to figure this out for more than a year. All was running until HVAC company came to replace 2 thermostats with nest and rewired 2 HVAC units (a front of house and a back of house ...
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26 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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44 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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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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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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2answers
29 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
38 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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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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Air Conditioning Thermostat Wiring

A set of three air-conditioners cool a storage building in an American sub-tropical environment. There is no heat: AC only. Cooling is signaled by switching the RED (24V) to: Yellow wire (cooling ...
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17 views

Relay requirements for Heatpump Thermostat

I would like to understand if three 3-relays are enough to control a heatpump. As I understand it, 24V AC is applied to: Green: Fan Yellow: Cool White: Heat When designing a network connected ...
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50 views

Can I calibrate this thermostat? (Cadet brand, 240V)

My thermostat operates but seems to be badly calibrated. It will hold temperature, and you can adjust that temperature, but its not the temperature it says on the dial! It goes much higher than the ...
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24 views

Thermostat Relay Positioning

A Florida AC-only storage building is equally divided sections each with: a single hallway to provide access to storage units 3 doors (25 feet apart) provide building access into one of the hallways ...
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21 views

Wiring c wire to current valve controller

I am looking to hook up a wifi smart thermostat and realized while I have 3 wires hooked up to my old thermostat, the common wire is not hooked up to anything in the basement. I'm wondering if I can ...
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2answers
28 views

Relay in Thermostat: current capability \ rating

When designing a thermostat, a relay must swtich a 24V AC signal to call for cooling / heat / fan etc. Industry standard thermostat wire color code used for most systems: White. The white wire ...
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1answer
66 views

Rth5160d1003 New Thermostat wiring from Older 7 Wire Setup o & b wires?

I need help with wiring up the new thermostat. I have a Gas furnace heat with heat pump. Goodman Units. The old thermostat G=GREEN C=BLUE Y=YELLOW R=RED O=ORANGE b=BLACK E=WHITE. The new thermostat ...
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1answer
51 views

installing ecobee SmartThermostat with Voice Control on older home

I recently purchased the most recent ecobee Smart Thermostat with Voice Control. The existing thermostat needs to be updated. However, I'm not sure if I'm able to install this without installing the ...
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Fan will not turn on in my wall radiator

Last year it was super hot water running through it constantly 24/7 all winter with no thermostatic control. I had to let the fan run for more heat. If I went to bed and left it running the ...
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1answer
30 views

Boiler only runs for 4 minutes then shuts off

I have a Slant/Fin boiler that's attached to a old White and Rodgers thermostat, typically the boiler only runs for about 4 minutes before it shuts off. This small period isn't really heating up our ...
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2answers
82 views

How to correctly wire a bathroom heater switch

I have an old Honeywell thermostat-type switch that controls the heater in the bathroom. Teenagers frequently forget to turn it off and so it runs for hours. I want to replace it with a push-button ...
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0answers
30 views

2 humidistats for 1 humidifier

I have two zones in my house with a damper system and want to move away from using my humidistat to control the solonoid valve on my humidifier and instead use my Nest thermostats. My zone control ...
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1answer
44 views

One Furnace, Dual Zones — Install Sensi on each?

Just bought a new (<6 years old) house and it's two stories, but only has a single furnace in the attic and a single condenser outside. However, there are two thermostats that work (semi) ...
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3k views

Does a thermostat need to be connected to the fuse box? My builder says no?

I just purchased a home, and was in the process of replacing the thermostats with Nests. I flipped off all the circuits in the fuse box, and the thermostat on the first floor powered off. However, the ...
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0answers
30 views

Thermostats with or without variable temperature differential (swing)

I am looking at replacing my thermostat, and don't really need or want one with geosync. I am thinking of the honeywell RTH9585wf. Currently I have a lux that is not wifi but programmable. It ...
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2answers
91 views

New thermostat for hydronic heating, no wiring labels, 3 wires

This hydronic system was not working when we bought our home. The fan would kick on with a manual switch but when you changed the temperature settings to go above the room temp nothing would happen. ...
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1answer
82 views

240V wiring and a thermostat

Newbie here. I do a bit of home electrical work at the most basic level. (Replacing outlets and switches. Running a new line off an existing outlet. Nothing that would even elevate me to an amateur ...
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2answers
24 views

thermostat wiring

Consider a simple two wire thermostat for a heating system, as shown in this diagram from electrical.online.com. There are two wires going into the thermostat, one, Rh, from the 24vac secondary of the ...
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18 views

Issue Installing Ecobee 4 on 4 zone boiler with Aquastat

I have a 4 zone valve boiler system. Each of the zone valves is Honeywell. I have a 24-volt transformer along with an aquastat. I have attached a photo of the wiring diagram from what I can tell ...
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1answer
63 views

Low Voltage C-Wire at Thermostat

Looking to install an ecobee thermostat and decided to measure my common wire before unhooking anything. I tested the R, C wires and see they are only reading 14v, whereas R,Y, and R,W are reading 28v....
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1answer
75 views

Air conditioner locating c wire on old unit

Hi guys I'm trying to figure out I'm using a dual heat and cool thermostat so i decided to get myself a smart thermostat and want to connect both thermostats into 1 but I'm having trouble location the ...
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17 views

Furnace/thermostat require constant power reset/“reboot”

I have an AprilaireProgrammable thermostat attached to York furnace?Ac unit. The set point is usually around 22 degrees, and the room temperature is reading around 20 degrees. The furnace is not ...
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1answer
41 views

Add “C” wire to NEST

I have a NEST thermostat. My heating and cooling system is in the attic.I need to add a "C" wire to the control board, but I can't find out where I need to open the unit in the attic to see where the ...
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1answer
209 views

No C Wire Nest Thermostat

I just installed a nest thermostat. The previous thermostat did not have a C wire attached. It G, RC, (RH Jumper), Y and W. When I hooked up the nest thermostat it was short cycling the blower fan ...
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1answer
79 views

Is a pulse width modulating thermostat compatible with a W2 auxillary heating (Nest compatibility question)

I have the wiring configuration for a RHEEM thermostat Pictured Below. On it, there is a "V" wiring connection which according to the manufacturer is for "Pulsed width modulation" type heating. On the ...
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3answers
76 views

Cheap digital thermostat turns off furnace when cold?

I woke up this morning and my thermostat which looks like a pocket calculator was just turned along with my furnace. I pressed both buttons and it turned back on, but my house was freezing cold. ...
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35 views

Very Old thermostat with TR wires

I want to buy a new smart thermostat, but am confused on the old wiring. I have single zone 120year old gas boiler (converted from coal, then oil, now gas). No cooling. The old honeywell thermostat is ...
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2answers
58 views

Theory: How do thermostats without a “C” common wire get powered?

My simple question is: When a thermostat has four wires: white, red, green, and yellow, the red is for 24V (AC?) and the white/green/yellow are for heat/fan/cooling. The role of the thermostat is to ...
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1answer
76 views

Can I use a nest thermostat for two heating sources (Furnace and electric floor heating)

Current situation: My home is currently heated with central air. Not my first choice, but that's what I have. I have brand new 98% efficient modulating furnace controlled by a Nest thermostat(no AC)...
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1answer
87 views

Electric water heater thermostat keeps tripping and needing reset

I have a 40-gal A.O. Smith Promax electric water heater (see pics below). It was a few years old when we bought the house, and we've been living here about 10 years. So I realize the heater may be ...
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2answers
525 views

Identify voltage by looking into gang box

I was replacing few of my old manual thermostats with smart thermostats. While installing the new ones, I noticed that some of the gang boxes have 4 wires (2 black, 2 red). Some of them have 6 wires (...
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31 views

Nest thermostat wiring problems

Removing my old Honeywell thermostat to replace with the nest. I live in Florida and my ac unit is 10 years old. I’m not sure if I have conventional heat or a pump. I took a picture of the old one but ...
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1answer
70 views

Use a 2-wire line voltage thermostat on a 24v / low voltage 2-wire furnace

This is an ancient furnace at my aging mother's. Basic 24v thermostat, two wires only, the original from my childhood used a mercury switch. There are some commercial, line voltage, 2-wire thermostats ...
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1answer
39 views

Help with a Nest E install on a old HVAC system

Hello I am trying to replace this thermostat with a Nest E but this has proven more complicated than I thought: I plugged all the cables to the nest adapter and figured that the blue wire which wasn'...

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