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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2answers
4k views

Can I piggyback a thermostat with a C Wire hookup on a furnace?

I'm trying to install a new thermostat that needs a C wire hookup. There are currently 4 wires running from the thermostat to the furnace, none of them are a c wire. When I look at my furnace itself ...
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3answers
25k views

Why does the gas furnace blow cold air at the start of the heating cycle?

What does this problem sound like? There is a 25 year old gas furnace in the house we rent. (The guy that owns the place claims there is NO problem at all. He said the igniter is brand new and ...
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2answers
36k views

Why is my A/C unit running when the heater runs?

So it finally got cold here in AZ. We switched our thermostat from A/C to Heat. Now for some reason when the electric heater runs, the A/C condenser unit outside kicks on too. This is our first winter ...
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1answer
885 views

Should fan on heat pump be delayed turning off when system stops?

I have a heat pump system with emergency heat. I have a Honeywell RTH7600D thermostat. When the heat is running and I turn the temperature down, the system immediately stops. Isn't this inefficient ...
3
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2answers
306 views

C wire thermostat assistance

I am trying to install a new wifi stat. The wiring seems to all be there but apparently not connected correctly. So far I have tried using the green wire from the furnace, the blue and the white from ...
3
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1answer
2k views

Does Nest utilize all the benefits of a communicating furnace

We just got a new furnace, the Lennox SLP98V. We have it hooked up to a Nest and its working fine. It is set up with two stages. We also have a whole house humidifier set up to it as well. Lennox ...
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5answers
25k views

HoneyWell Wifi Thermostat and C wire

I just bought the HoneyWell Wifi thermostat and so wanna use it. However my old Thermostat was battery powered and does not use the "C" wire. I opened up my panel and found that there were three ...
3
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2answers
713 views

How to add C-wire from Laars mini-term

Folks, I am having problems connecting my Nest thermostat to a boiler. Given Laars Mini-term JVS series with Temperature Control PCB Module (pictured below) When I short Com call and Heat call wires ...
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2answers
1k views

Can I use an unused wire as a “C” wire?

I just bought a new thermostat that is Wi-Fi enabled and it requires connection to a "C" wire. The old thermostat does not have one running to it, but there are other unused wires. The thermostat ...
3
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1answer
154 views

How come the temperature is sometimes not maintained?

First let me come right out and say that I am a software guy and this seems like a hardware problem, so I already feel out of my league. That said, here's the deal: Background: I have two-zone "hot ...
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3answers
58 views

Is it wrong to install both a whole house humidifier and a whole house de-humidifier?

I live nearish Pittsburgh. Our summers can get pretty hot and humid and our winters can get pretty cold. We have been planning to get a whole house humidifier because the house gets really dry in ...
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1answer
44 views

Can't find HVAC C terminal

Could any of these be the c terminal on my hvac unit? There's already a c wire there, just can't figure out where to connect it.
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1answer
3k views

Why won't my Central Heating Boiler turn off with Nest thermostat installed?

I bought a second hand Nest Thermostat v1 (the European model with heatlink). I installed it and the Thermostat seems to work. The central heating boiler (Vaillant hrPRO CW3 VHR NL CW 3/3) seems to ...
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1answer
594 views

New Thermostat Ecobee3 to Old Galaxy GG-75 boiler - Needs common wire

I would like to replace my old thermostat with a new Ecobee3 thermostat. HVAC system is a Slantfin Galaxy GG75 boiler - single zone. (No air conditioner.) Current set-up has only a red and white ...
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4answers
5k views

Is the Nest thermostat smart enough to turn itself on BEFORE you get home?

I'm wondering if in "Away" mode, is Nest smart enough to learn about when you come home, and kick on approximately 30-40 minutes BEFORE then? Or does it only kick on when it senses you've come home? ...
3
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1answer
784 views

Can I connect an additional wire to HVAC system where all the terminals are full?

I'm installing a new thermostat (ecobee Smart Si) and it requires "C" wire. I checked before I bought, and saw an unused blue wire behind my current thermostat. However after connecting everything the ...
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3answers
2k views

How do I connect a C wire to an Utica PEG112CDE steam boiler?

I want to upgrade my old mercury thermostat that I currently have to a newer programmable thermostat. This little DIY project is for my first late 1920's home that I recently purchased. I currently ...
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3answers
1k views

Can a furnace with a variable speed blower be used in a multistory house?

I just had an HVAC guy out to give me an estimate on a new Carrier Infinity series furnace and he said the second floor rooms will always be colder because the thermostat is on the first floor and not ...
3
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1answer
2k views

How can i figure out which wires go where, if the colors at the furnace don't match the thermostat?

I have an old system and want to update the thermostat however, the white-rodgers thermostat has no letters such as R,G,B,Y,W,C So I checked out the furnace terminate wires and the colors of the ...
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3answers
7k views

Trying to wire a 240v line-voltage thermostat

I am trying to replace my old 240v line-voltage thermostat with a modern version. The problem is that after wiring the new version in like the old it doesn't work. I have (2) 12-2 wires coming out of ...
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1answer
777 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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3answers
49k views

Hvac Fan only blows in 'fan on' mode while heating

Our HVAC Fan only blows in 'fan on' mode while heating. In other words the fan will not blow in heat mode if switched to "fan auto". Both fan on and fan auto modes work when cooling. See image below, ...
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1answer
194 views

Can't get fan working on thermostat

I recently purchased a new thermostat. My old thermostat worked for heat (no AC either) but the fan wouldn't go on when I turned to "On" (in hopes to move some cool air from the basement up during the ...
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2answers
2k views

How do I wire this 240v fan motor and thermostat

I'm trying to wire a two stage exhaust fan for my greenhouse. The motor comes set up for 240v wiring and is to be controlled by a thermostat. I undertsand how to get the 240v from the panel, but can't ...
3
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1answer
130 views

Is it OK to leave the thermostat unwired?

So I went to replace the batteries in my thermostat and when I pulled it off I noticed a black wire was unplugged. I'm not sure if it's suppose to be like that or if I accidentally pulled the black ...
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1answer
1k views

How do I install a WiFi thermostat with a Well-McLain steam boiler?

I have a Weil-Mclain 150000 BTU steam boiler, and have only 2 wires connected to my thermostat, but would like to add a new Honeywell WiFi thermostat. I have no C wire, no A/C, or any other type of ...
3
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1answer
46 views

Furnace Connect G Wire

I have a dual energy electric/oil furnace that is wired to a thermostat with 2 wires R and W. I don't have any AC. Inside the furnace there is a switch relay to control the fan but it is not connected ...
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0answers
48 views

Can I use this White Wire for a thermostat C wire?

An AC-only machine cools a storage facility: no heat. The 30 year old thermostat is to be replaced with a wifi thermostat, which requires a C-wire to power the electronics. There are 4 wires: Red (...
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2answers
72 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
1k views

Why my baseboard heater won’t turn with new thermostat?

I have a pair of electromod basement heater. The label on each of them show them show 750/1000W. Power supply to this is 240V I am trying to replace the old manual thermostat with a progrmabale one. ...
3
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1answer
240 views

How should my third-generation Nest thermostat be connected?

I have an old Honeywell Q674 thermostat with mercury in the house we just moved into. I'm attempting to upgrade to the nest 3rd generation thermostat, however the wiring labels are VERY different. ...
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8answers
56k views

How can I use a separate transformer to provide a C wire to my thermostat?

Update 02/02/2019 I appreciate all the responses and help but unfortunately i must have not seen the emails stating there were responses! I am now looking into a NEST thermostat and was curious if ...
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3answers
20k views

Controlling 110v swamp cooler using Nest thermostat

I currently have an HVAC system that is connected to a Nest thermostat (2nd generation) and I'm planning to use the same Nest thermostat to control a 110 swamp cooler that is currently not connected. ...
2
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2answers
13k views

Can I pair two thermostats to work with a single zone system?

I have a southern California two-story home built in the late 70's. Its a single zone system with both heating and AC. The thermostat is located downstairs. In the summer the upstairs gets too ...
2
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4answers
2k views

Is there a special low temperature thermostat?

I have a gas ceiling mounted furnace for my garage. I want to set my garage at 35-40° F (1-4° C). Is there a special thermostat to control furnace at that low temp? (I've seen one works as low as 50°...
2
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2answers
2k views

Pulling wire using previous wire?

I’m trying to pull a new thermostat wire down from a first floor room down into the basement. The exit point in the basement is in the ceiling, between two ceiling boards pretty inaccessible. Would it ...
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2answers
12k views

Honeywell T6360 wiring - follow installation wiring guide positions or numbers?

The following picture shows a Honeywell T6360 Room Thermostat wiring connections. You will note they are numbered in the order 2 3 4 1 5 6. The Installation Instructions that accompany this unit, ...
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1answer
170 views

How do I temporarily remove a Côr WiFi thermostat by Carrier to repair a plaster wall?

The model number is TP-WEM01-A, installed with the "large backplate", as pictured below. There are no visible screws, etc. I have the manual but it is no help.
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2answers
62 views

what brand of thermostat is this

The cover is missing from this thermostat, so I don't what brand or model it is and I don't have the manual for it.
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2answers
1k views

Using a solar system with a condensing boiler for the central heating instead of tap-water?

According to the manual of my AWB ThermoMaster 2HR 28.02WT Condensing boiler, it is compatible with a pre-heating solar system for tap-water only. It even has extra facilities to ensure that the ...
2
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1answer
190 views

How to remove the wall plate behind Honeywell thermostat

I'm trying to install a smart thermostat. I have a Honeywell programmable thermostat now. However, I found that there's a wall plate in back of the back plate, and it's secured to the wall (not by ...
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3answers
2k views

Removing old thermostat when replacing electric baseboard heaters

We're renovating a 30 year old home in the US and replacing three 240 volt electric baseboard heaters with new, modern heaters. Currently, each of the three 15+ year old heaters are wired into their ...
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1answer
38 views

Do any home thermostats have an adjustable control range?

I am having trouble with AC and need to replace it soon ; so I have been listening to it cycle .I knew it only stayed on a short time but I just found it runs less the 2 minutes ; that is with ...
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3answers
7k views

Do I have one or two 24V transformers in HVAC control circuit

I have two old thermostats (one for heating, the other for cooling) that I would like to replace with a single Nest E unit. I have central air and gas heating. Cooling thermostat has the following ...
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2answers
331 views

Please help me understand my HVAC wiring

I'm trying to replace an old thermostat with a WiFi one that requires a C wire to power it. When I opened the panel on the air handler 1 (where I'd like to connect the thermostat to), there's no wire ...
2
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1answer
971 views

Using 15-amp thermostat on a 20 amp circuit

I live in Washington state. I have a 20 amp circuit breaker on a circuit that drives two fan-forced heaters, connected through a single line voltage "dumb" thermostat, unknown rating. I would like to ...
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1answer
964 views

Wiring thermostat fan ON

My thermostat is a Honeywell that goes to an old furnace with a Honeywell furnace controller (the board that provides the spark for my gas furnace, among other things like 24V, TH-W, etc.). The ...
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3answers
7k views

Before replacing a thermostat, is it enough to unplug the furnace?

We have a thermostat that we need to replace. Our system is I think pretty typical, the thermostat I think controls the furnace and fan, and I suppose the furnace relays controls for the air ...
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2answers
2k views

“C” wire in wall! Where does it go in air handler/furnace?

Got a wifi thermostat. Behind the old thermostat was a blue "C" wire. The other side of the blue wire in the equipment room isn't plugged into anything. I need to get the 24v common hooked up to this ...
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1answer
1k views

How to add C wire to a very old 2-wire Lennox G16 Gas Furnace?

I recently bought a Sensi Thermostat with Wifi to replace my vintage one. I thought it would work with my 2-wire heat only system because it has batteries , but found out that using the Wifi feature ...