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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1answer
31 views

How do I convert an old Satchwell/Sunvic TLX2203 thermostat wiring to line voltage wiring?

I have an old Satchwell/Sunvic TLX2203 thermostat. It has 3 wires connected to it which look to be: switched live (green) live (red) neutral (black) (at least I think that's the case) I would like ...
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27 views

My central heating comes on when it feels like it

I have checked the wireless thermostat is sending a demand signal to the receiver but boiler isn't firing up (BTW my hot water on demand is working fine). Later on the heating comes on until i turn it ...
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1answer
47 views

How do I convert my fireplace switch into a thermostat switch?

I have a fireplace that's controlled by a regular on/off switch. How can I convert it into a thermostat switch so that the fireplace shuts off automatically whenever the room gets warm enough? If it ...
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1answer
2k views

C wire - thermostat - not providing power

I'm replacing my old Honeywell thermostat with a new Wifi thermostat. My old/current one is battery powered and doesn't use the C wire. I found the C wire behind the plate. I connected the c wire to ...
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16 views

Heat pump thermostat wiring, can I leave the Optional C terminal empty?

We have an old Carrier Heat Pump system. The thermostat tells me that "C IS OPTIONAL WITH BATTERIES". The thermostat does have batteries. So I can leave the C terminal empty and use the ...
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1answer
296 views

Can't get wifi thermostat to work with gas boiler

I bought a Sensi WiFi thermostat and I have been trying to install it. I can't quite figure out how this wiring should work. Here is a link to pictures of the boiler and the current thermostat. The ...
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16 views

New Thermostat / Re-wiring [closed]

I Had an I comfort WI-FI enabled Thermostat with 4 wires: R, I+, I-, and C. I bought a honey well TC3 and when i hookup the R and C wires there is no heat or cool function. Do i need to change the I+ ...
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1answer
72 views

Is my control board bad?

I have a Goodman evaporator/gas heating unit that runs the central fan motor constantly after it is powered up a couple of seconds. This happens regardless of what wires are hooked to the control ...
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1answer
40 views

Can I directly add a Common wire to this point on a 24VAC transformer, or will load be too high? (70mA)

Referencing This excellent answer I have a two wire furnace controller, 24VAC, no common. I measured the current draw of the relay (when the thermostat wires are shorted), it draws 0.2A Wish to add an ...
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2answers
38 views

Ecobee 3 - I have 3 Wires

I have three wires coming to the existing, very old, thermostat: Black, but wired to the "R" terminal of the current thermostat. White, but wired to the "W" terminal of the ...
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1answer
82 views

Swapping to Hive thermostat. 4 wire communicator has 2 wires per post

I'd previously asked if I could swap my wires from the 4 wire communicator to the larger board and was told I could. I finally found time to do it. However, as I was preparing to move the wires, I ...
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1answer
4k views

Where to connect my “c” wire on the boiler side. Weil mclain gas boiler

Im just curious if the “c” terminal on the plug in relay is where im suppose to connect my “c” wire on the boiler side. I have 18/5 wire ran already. Just need to find out where to terminate. To the ...
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1answer
30 views

Installing Nest From HoneyWell T8575D Condo 8-Wire thermostats

My condo apartment current has the HoneyWell T8575D installed and I want to switch to Nest. But I couldn't find which Nest port should the "Fan Common" line go into. The wiring from the wall ...
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1answer
20 views

HVAC: adding a C wire for Nest thermostat

Just installed a brand new gas boiler, want to keep using my existing Nest thermostat (they are compatible according to Nest). Current system only has two wires: Rh and W Nest is designed to steal ...
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27 views

Nest thermostat + SIMPLE dual transformer setup. What is wrong?

I have a a VERY SIMPLE dual transformer system (Rh is the heating transformer and Rc is cooling transformer) for heat all I need is (Rh + W1) for AC all I need is (Rc + Y1) With this dead simple ...
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1answer
65 views

Main burner in NG fireplace goes out

What could be the reason of main burner going out intermittently. The pilot stays on. The voltage of the thermopile is 638mv when burner is off. The thermostat is a manual heat only. When I short out ...
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33 views

Thermostat wiring identification - missing yellow wire/extra wires

Help please and apologies in advance for lack of technical knowledge! I'm looking to replace my old Honeywell 8022C 24v thermostat with a Nest, and have failed on several levels now I've taken a look ...
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1answer
138 views

Old thermostat to Hive thermostat

My wife decided we needed a smart thermostat... which means I need to install said thermostat... Currently a Bryant Evolution series is mounted. She purchased the Hive with Hub when it was on sale. ...
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40 views

Water heater not producing hot water but everything seems to be working?

We just bought a house and the previous owner had a brand new water heater installed. The first day we took a shower it was not very warm and the next day there was no hot water at all. I checked the ...
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1answer
185 views

how to connect C wire for ecobee lite to Weil-McLain EG Series-5 gas steam boiler

I want to upgrade from a battery powered Honeywell thermostat to an ecobee3 lite. This is for heat only. My current Honeywell has two wires: Red and White. Missing is the C cable. There are enough ...
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3answers
60 views

Thermostat location in 3 story building

Where would you place the thermostat in a single zone, 3 story building. Tt's a multi-family residential, 3 units, one unit per floor. The boiler is a high-efficiency condensing boiler in the basement,...
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2answers
172 views

How to verify that resistive load thermostat is dead

I have an electric heater, connected to a resistive load thermostat (240V). Yesterday we found the thermostat apparently totally dead (display off, etc). I've checked the breaker, of course. (There is ...
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35 views

Baseboard heater powered by a switch, not thermostat

Our finished basement has electric baseboard heat. The baseboard is powered by a light switch, so I either have the heat on or off. Can I take out the switch and use the wiring to connect a digital ...
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25 views

Connecting New Thermostat C Wire To Transformer

Looking to add a C wire to my 2 zone system (new smart thermostat). Since the original wiring was 2 wire, I ran a new set of 5 wire lines. The link below shows how my current set-up is wired to the ...
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1answer
82 views

Furnace with no “C” connection

I have a mobile home furnace. This furnace only has a 4 wire connection terminal, G,W,R,Y. I also have a condensing unit outside with the 24 volt 2 wires coming to the furnace. I know I connect one to ...
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1answer
55 views

New ecobee3 lite, have heat but no cool option

I recently installed a new ecobee3 lite. When I completed the setup process, I found that there was no option to enable cooling. My original setup had both heat and cool options. I believe the option ...
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1answer
40 views

Replacing old 2-pole line volt thermostats in a 120V hydronic heating system - is this configuration safe and acceptable?

I am replacing several old mechanical 120V 2-pole thermostats each of which controls both a blower fan (which blows air over hydronic coils to push warm air into the room) and a single central ...
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1answer
20 views

Different wirings on 2 thermostats controlled by a 2 minizone system

I was replacing my 2 thermostats controlled by a 2 mini zone system (Trol-A-Temp). One of the thermostat has 6 wires/terminals (Y,W,R,G,O,B). The other one has 3 wires/terminals (Y,W,R). I was ...
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2answers
547 views

Temperature of water in the shower fluctuates - will a cheap thermostatic tap help?

I recently moved to an apartment where temperature of water in the shower fluctuates and we called for a plumber. He either cleaned up or replaced one part (I think it was the mixer - nothing visually ...
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1answer
66 views

2 wire thermostat wire want to be able to select fan only

I have an older furnace with only 2 wires at the thermostat "white and red". No issues at all with my system works as should. Thermostat is new Honeywell basic model not smart. I want to ...
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2answers
440 views

Connect Wifi Thermostat to Goodman GMP050-3?

I'm trying to connect up a wifi thermostat to Goodman furnace, specifically the GMP050-3. I've done some reading on this but I'm still not quite sure how to go about it. Specifically, I'm not sure ...
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0answers
17 views

Horstmann C27 to Nest

I'm in progress of changing Horstmann C27 with Nest Learning Thermostat Gen3. I'll share the images below, I'm looking for a way of mapping the cables to the Nest. C27 supports both Hot Water and ...
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1answer
7k views

Honeywell RTH6500 WiFi Thermostat wiring questions for a heat pump

I'm trying to install a new Honeywell RTH6500 thermostat on an old heat pump system that has regular plus emergency heat and the closest matching diagram says to put both the white "W2" wire and black ...
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1answer
1k views

Converting I+ I- thermostat to 'standard' wiring

I've been replacing my thermostats with the RadioThermostat CT50, which reports to my home-brew home control/alarm system. I have a 3-year old AireEase 4-ton unit in the shop that has a Comfort Sync ...
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1answer
24 views

Use Honeywell VisionPro without EIM?

I just acquired a Honeywell VisionPro TH9421C1004 thermostat but I didn't get the Equipment Interface Module (EIM) with it. Can I still wire this directly from my furnace? It only has 3 wire ...
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1answer
66 views

Hook up new thermostat

Top brown picture is my old thermostat white is the new one , do I have it wired correct? On out side unit we have replaced motor, fuses, compassator ,cc contactor ,relay . We have a heat pump. But ...
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1answer
812 views

Need help adding a C wire for a wifi thermostat

With the increasing popularity of wifi thermostats I know this question has been asked many times, however I'll ask it again fr my specific situation. How do I add a "C" wire to my existing air ...
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0answers
30 views

Changing Weathertron to Honeywell Thermostat

I have a GE Weathertron (model 3AAT80 1A1/2A1) that I want to switch over to a Honeywell (RTH6360). Most of the wiring seems straight forward, but ... R (Weathertron) to R (Honeywell) O ...
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0answers
56 views

Need help changing from Trane thermostat to Honeywell T9

I currently have Trane thermostat (TH8320U1040) and trying to change it with Honeywell T9 thermostat. On Trane I currently have following terminals connected: Wire Color - Terminal Name Orange -...
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1answer
7k views

Central Heat Won't Turn On When I Raise the Temperature on Nest Thermostat

I'm sure my heater is working. It's 47 degrees outside, and I'm only a little cool inside. My Nest thermostat is set to 67 degrees. The screen on my app (which agrees with the thermostat) is shown ...
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1answer
1k views

C wire and smart thermostat

I'd like to install an ecobee3 thermostat, but I'm not entirely sure about my wiring. The current thermostat seems to only have a W and RC wire coming into it. There is also what appears to be a blue ...
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1answer
255 views

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

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
47 views

Thermostat wiring for fan only

I have a White Rogers 1E78-144. My house has heating only and no AC. https://climate.emerson.com/documents/ie78-non-programmable-thermostat-instructions-en-us-4209010.pdf The current wiring only ...
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1answer
777 views

Wiring a C (common) wire to a Triangle Tube Prestige Excellence 110?

Wiring noob here. Can someone give me step-by-step instructions for where and how I should attach a C (common) wire to a Triangle Tube Prestige Excellence 110 boiler for a ecobee3 thermostat? I think ...
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1answer
135 views

C Wire in Air Handler

Can someone please help me find where to connect a C wire for my smart thermostat? Here are some pictures with descriptions. It is difficult to get to the 24v connection in the back. My schematic ...
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1answer
52 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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2answers
177 views

Replace thermostat wiring from my Carrier Weathermaker 8000 to my Nest thermostat

I'd like to replace the wiring from my Carrier Weathermaker 8000 to my thermostat to add a C wire. I assume I need to turn off the Carrier first, but there is no power switch that I can see on the ...
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1answer
19k views

How do I turn off the power to my thermostat?

I'd like to replace my thermostat with a new one. My current thermostat is one that doesn't have a C-wire and is powered by batteries. Now, my question is... is there a switch for the power that I ...
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1answer
100 views

My thermostat and heating system was working fine but the batteries read low power

So my Honeywell non WiFi Thermostat was working fine except for the low battery signal in the top right-hand corner. We took the face off of the thermostat of course shutting the Heat and fan off ...
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1answer
40 views

Why is my thermostat reading falsely high temperatures?

Thermostat is reading crazy high temps when it is really 67. Furnace won't deliver heat. Fan works. Is it the thermostat (batteries replaced already) or the furnace?

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