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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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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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
956 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
57 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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1answer
97 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
59 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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71 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
98 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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36 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
9k 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
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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
51 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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1answer
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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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0answers
74 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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1answer
27 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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0answers
23 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
49 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
53 views

Need help disassembling Groehe shower thermostat

I have what I think is a Grohe 19624 Shower thermostat like this the one shown here: http://www.guillens.com/index.jsp?path=product&part=392046. It is leaking and I need to get it apart to ...
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1answer
220 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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3answers
690 views

Using a ground wire as a thermostat C

Just theoretically, A C wire is just a return for 24v transformer right? So if you were in a situation where you have access to the slab, or just a standard outlet or switch receptacle could you wire ...
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0answers
16 views

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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2answers
161 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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1answer
33 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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33 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
86 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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2answers
4k views

Is the transformer bad on my Central Air Conditioner?

Need some help diagnosing a problem. My very old central AC unit isn't working. It's just AC and about a year ago I connected a C-Wire to the air handler when swapping the thermostat for a wifi ...
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5answers
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
1k views

Carrier Furnace (6-wire) to Honeywell thermostat --> no cooling :-(

Carrier Furnace w/ Honeywell WiFi Thermostat I have a Carrier furnace with the cheapest programmable thermostat (TB-PHP01) that came with my house. The thermostat uses six wires: Y, C, R, G, W, and O. ...
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75 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
106 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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2answers
31 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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1answer
127 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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4answers
8k views

Can a wifi thermostat to control milivolt operated fireplace?

Have a propane gas fireplace, controlled by a hand held remote control thermostat. Wish to install a wall mounted wifi controlled thermostat, heat only. Seems that all available thermostats operate ...
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1answer
309 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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0answers
29 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
116 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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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
45 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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2answers
203 views

Smart Thermostat and 24 volt transformer direct to thermostat

I have a hot water boiler and separate AC system and bought a wifi smart honeywell thermostat to get a C wire- installed a 24 volt transformer that has two wires if one goes to the C where should the ...
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0answers
738 views

Nest 3rd Gen 24VAC two transformer issue

Hopefully this will finally solve the issue with my Nest. I bought a Nest 3rd Gen Learning Thermostat and followed the instructions to the tee. I have a two transformer system (Forced Air A/C and ...
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2answers
85 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
321 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
127 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
78 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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0answers
38 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
69 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
153 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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