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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29 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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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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20 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
88 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
49 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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21 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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16 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
46 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
46 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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16 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
36 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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113 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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37 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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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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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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39 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
26 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
517 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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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
32 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
36 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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34 views

Connecting two thermostats in parallel to control old millivolt wall gas heater

Hello I have a very old propane wall heater on a vacation home. It is a "millivolt" type that does not require external power (no battery, no 24 VAC, no 110 VAC). It is a simple 2 wire system. No C ...
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1answer
82 views

I have a garage heater but I don't want it to run at all if the temperature outside is above 45 degrees

I was thinking about putting two thermostats in series so that I could set the garage temp to ~65° but ONLY have it come on in the event that the outdoor temp falls below ~45°. The garage does get a ...
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1answer
56 views

Thermostat/Furnace Wiring Confirmation

Like so many others, I am looking to install a new wifi thermostat with an older furnace. I've searched across the Internet and I have a pretty good idea of what is needed and why; however, I have a ...
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85 views

Where to connect a C wire for my smart thermostat

I am trying to connect the c wire but I'm at a crossroads of sorts. I have a dual zone so there are 2 thermostat wires come into what looks like a relay box ( see pictures) I have located the ...
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Aprilaire 600, No water to filter

I don't get 25v to thermostat. If I short out the outside air on the control panel I get the thermostat to kick in and I get water to the filter. I can't locate the outdoor sensor if ti is bad
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1answer
44 views

Red wire in place of C-WIRE?

I just moved into a new home and was trying to connect my Ecobee thermostat. I know it requires a C-wire. I found the wire wrapped around the others in the previous thermostat, which didn't require ...
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2answers
81 views

Thermostat wiring

Can someone look at wiring of my thermostat and HVAC panel? I don't understand why R wire is connected to RC at thermostat. I am also not sure why Y wire is not connected at HVAC panel. Here is my ...
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1answer
37 views

Checking voltage on a 240 volt thermostat

Very basic electrical question. I have a non-functioning double pole thermostat (wired to an electric baseboard). I'd like to replace it, but of course my breakers are not labeled. Is there any way to ...
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0answers
59 views

Honeywell RTH5160D Thermostat Wiring w/ Heat Pump

I have installed a Goodman heat pump and a Honeywell RTH5160D thermostat. I chose that thermostat because it is supposed to switch automatically between cooling and heat modes. The system has been ...
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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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One Thermostat for 2 Air Handlers

We have 2 single stage AC/NG gas furnaces serving a common area. We would like to set them up for 2 stage operation on a common programable smart thermostat. Should I combine the R and C wire from ...
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Replacing thermostat and metal plate inside wall cutout

I am replacing my Honeywell thermostat. I removed the old one and there is a metal plate inside the drywall cutout that the old one was screwed to. I need to remove the plate because the screw holes ...
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21 views

Nest Thermostat E Wiring Question

all, I wanted to get a Nets Thermostat E, but my current thermostat doesn't have a C wire. From what I read online, it's better to use a C wire, so I was considering adding a Venstar Acc0410 adapter....
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30 views

Tried switching old thermostat with digital one…wasn't working, so switched it back to old one and ir is still not working

I decided to upgrade the old thermostat control for heating/cooling, to a simple non-programmable digital unit. I simply attached the wires to the corresponding terminals in the new unit. After ...
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1answer
21 views

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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Thermostat Unit Pops Out When Trying to Close

My father has a radiator in his house that is missing a Thermostat Unit (the plastic thing that screws on top of the valve - not really sure what it's called). I managed to screw on a unit from ...
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1answer
46 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
45 views

Connecting thermostat common wire to air handler or boiler?

we are planning to install a Nest learning thermostat in our house. On first installation attempt the device notified us that there was no power from the Rh or Rc wires which from my understanding is ...
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PTAC heat troubleshooting

I own a condo with two Islandaire EZ09EBMXH8N10AA PTACs, one of which is acting weird. They have self-contained A/C mechanisms, but the rooms are heated by pumping hot water from the building through ...
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1answer
35 views

How to add a C wire to an old Lennox attic furnace GS810-105N

I bought a smart thermostat for my house in hopes of cutting some bills a little. I read up on them, I thought, thoroughly and figured I could handle the task. However, upon climbing up in the attic ...
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2answers
28 views

Can I hook up the Glas WiFi Thermostat with oil furnace in basement and central ac in attic

I have an oil furnace in my basement with only 3 wires for the thermostat only 2 being used. I just installed central air in my house but air handler is in the attic with 5 wires for the thermostat 4 ...
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Pretty basic Honeywell Wireless Thermostat Questions

I thought I knew at least the basics of how the Honeywell Thermostat worked, but testing with a multi-meter dashed those presumptions. I have another question posted, but until I get the basics ...
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1answer
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Honeywell TH6320R1004 Wireless Thermostat with Two Transformers

I have a Honeywell TH6320R1004 and am trying to set it up to work with a second transformer (just added a Taco ZVC403 to an existing Taco SR503). The second transformer was needed to power the zone ...
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How to wire my new thermostat from old boiler switch

I bought a new thermostat hoping to replace a simple on/off switch for my boiler. I've never done this before and am confused about how I should arrange the wiring on the thermostat board. This is ...
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255 views

How do I turn off the programs on my White Rodgers thermostat?

I can't find anything on the internet about this issue. Sites like this: https://www.hunker.com/12279552/how-to-program-a-white-rogers-thermostat explain how to set up a program but they don't explain ...
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1answer
64 views

Where do I connect C-wire to Burnham boiler?

I'm adding a smart thermostat to one zone of a two wire, oil fired boiler system. I've roughed in a new wire and could use some help determining where to terminate it at the boiler. The wiring is far ...
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28 views

New thermostat turns fan off when set to on, never turns off on auto

My oil heat furnace was functioning normally on an old mercury switch thermostat, but I wanted to replace it with a programmable Honeywell 5+2 one. There were Y, W, G, R, and B wires screwed in on the ...
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2answers
145 views

How do you install a thermostat if you don't have Y or C wires?

My thermostat is a LuxPro LUX PSP511LCa. I looked behind the thermostat and I see the following: A red wire connected to RC A jumper connecting RH and RC A white wire connected to W A green wire ...