Mechanical or electrical device used to control a heating, ventilation, and air conditioning (HVAC) system, or other temperature reliant system.

learn more… | top users | synonyms

2
votes
1answer
465 views

What could be damaged if I shorted the R wire to the C wire at my thermostat?

OK... so in trying to install a thermostat (and testing to see if the old thermostat was bad) I inadvertently jumped the R and C... (I actually jumped the R and G terminals but the G terminal was ...
2
votes
1answer
246 views

HVAC electric thermostat panel “goes dead” and then live again all the time

I have this digital thermostat controlling my heater (gas). When I turn it on to lets say 66 deg, and the house is at 60, the HVAC will start working of course. Problem: After few minutes, the ...
2
votes
0answers
179 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 ...
2
votes
1answer
145 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 ...
2
votes
1answer
629 views

Where do I connect my C wire from my thermostat when there are two transformers?

I have a Laars gas boiler that has 3 heating zones. I want to replace the old mercury honeywell tstat on the 1st floor (heat only) with a newer honeywell RTH9580 wifi model. I've taken pictures of my ...
2
votes
0answers
266 views

Are w1 and w2 both energized during a second stage heat call from the thermostat?

Short version: does two-stage thermostat always close W1 circuit when it closes W2 circuit, or they might be closed independently? Long version: I have two-stage furnace, currently connected to older ...
2
votes
1answer
4k views

How can I add a “C” common wire to this system? [duplicate]

I would like to add a "C" / Common wire hookup to my hvac system and get a fancy new thermostat. I've read Options for adding "C" wire to thermostat and still have some questions. First of ...
1
vote
2answers
973 views

Is there a filter-reminder thermostat that uses run-time instead of total time?

My HVAC filter is in my crawlspace and is a hassle to change. I don't want to change it more than needed. "Change it every month" is bogus advice because in some months (like May) we don't have to run ...
1
vote
2answers
204 views

At what temperature does a WiFi thermostat stop sending a signal to the router?

I recently purchased and installed a Honeywell WP6500 WiFi thermostat and thanks to Stack Exchange, got it up and running. I have a house in New Hampshire, which I use occasionally during the winter. ...
1
vote
3answers
101 views

A/c makes the lights turn on and off! No Joke!

The lights on the first floor, upstairs bathroom and upstairs Laundry room won't work. The breakers did NOT pop The air conditioning was running this morning but is not working now. When the ...
1
vote
4answers
1k views

Can I provide a secondary power source for my thermostat?

The thermostat at my home is set up with only the 24 power and return through the relay. I would like to add a 'smart' thermostat, however the line is fairly well buried in the wall/basement ceiling ...
1
vote
4answers
3k views

Is it alright that I did not turn off the power while installing my thermostat?

I just installed the Nest thermostat, I forgot to turn the breaker off everything seems to be working fine. Is it safe to assume it is ok?
1
vote
2answers
826 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, ...
1
vote
2answers
1k views

What could cause a clicking sound in an underfloor heating controller?

I have a underfloor heating system installed in my apartment. Each room has a Uponor T-37 thermostat, hooked up to C-35 controller. The system is about four years old and recently I have noticed a ...
1
vote
5answers
8k views

How do I control a heat lamp with a thermostat?

My girlfriend is crazy about making bread. However, as the temperature is often very cold around here, I would like to make her a box in which the temperature can be controlled. I have purchased a ...
1
vote
4answers
749 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 ...
1
vote
2answers
3k views

Controlling separate heat and AC devices from a single thermostat

I have hydronic radiator heat powered by a gas furnace situated in one mechanical room of my house and a currently being installed central AC whose air handler is situated in another mechanical room ...
1
vote
2answers
2k views

How should I install a thermostat for a baseboard heater?

How would I go about installing a thermostat for my bedroom's baseboard heater? I've seen lots of articles on how to replace an old thermostat but I'm installing a thermostat for the first time here. ...
1
vote
2answers
1k views

How far apart is it okay to set thermostat during night and day

This isn't home improvement, per se, so please feel free to let me know if there is a better forum for this. I have been told by two people, one of whom is a boiler repair technician, that it's not a ...
1
vote
2answers
202 views

Can anyone identify this heating timer?

So, It's getting quite cold now and my central heating is just going on and off randomly. There is what seems to be an unbranded heating timer below the combi-boiler (Baxi). However I have no idea how ...
1
vote
1answer
48 views

Can I use Eneloop batteries in my thermostat?

I have this LuxPro thermostat http://www.luxproproducts.com/pdfs/spec_pdfs/PSD010Bc_NL_ENG_Manual.pdf There's a warning in the very first section that says to use only Duracell or Energizer Alkaline ...
1
vote
1answer
101 views

Can I change my standard thermostat to a Wifi one?

I have a (quite standard) TR-010X T6360A thermostat that looks like this: And this is the wiring diagram: Can I install the Heatmiser PRT-TS WiFi Touchscreen Programmable Thermostat? This is the ...
1
vote
1answer
64 views

How to install thermostat with plug in heater?

My house has three electric wall heaters in different rooms used to augment the gas forced air that heats the whole house. These electric heaters are mounted on the wall, but plug into standard 120v ...
1
vote
3answers
109 views

can I install a new thermostat by just turning off the power instead of turining off the circuit breaker?

Can I install a new thermostat by just turning the power off at the servicemen's switch, instead of at the breaker?
1
vote
1answer
1k views

Should I replace my mercury switch thermostat?

We have an old mercury switch thermostat in our house, You know the type, gold ring, very common. We are in new England on a gas/steam system. There is no central AC. We have been told by more than ...
1
vote
2answers
2k views

Can you terminate more than one common on the furnace C terminal?

TL;DR: Can you terminate more than one common on the furnace C terminal? Background: I've linked a diagram of how my non-programmable thermostat is currently hooked up. I want to replace it with a ...
1
vote
1answer
1k views

Why won't my shower fully heat up?

I have a thermostatic shower, but I can only get it to be luke warm. The aquastat is set at 60, boiler at 165. The tap water in wash hand basin beside shower is very warm. I have taken the cover off ...
1
vote
2answers
1k views

How do I disable a thermostat to prevent it from turning on the AC?

I need to disable my thermostat from turning on the AC. Yes, covertly. I think one of my housemates is missing his native Antarctica. So, the thermostat still must be active & setable, but I want ...
1
vote
2answers
88 views

thermostat batteries replaced, AC unit won't start

Came home from work to find no AC. I checked the thermostat and the display was blank. After replacing the batteries and resetting the program, my AC unit never started up. I checked: - The AC unit ...
1
vote
1answer
176 views

Replacement thermostat wiring

I have an American Standard heat pump AC. I'm replacing a White-Rodgers manual thermostat (where I move a switch from cold to heat) with a Honeywell RTH7600 (which will automatically switch from cold ...
1
vote
3answers
10k views

Adding a C wire to a new Honeywell WIfi Thermostat

I am trying to install a new Honeywell touchscreen WIFI thermostat and need to add a C wire to my terminal inside the furnace (using the help found at How can I add a "C" wire to my ...
1
vote
2answers
736 views

Wifi Thermostat wiring

Replacing 2 Hunter thermostats with a Honeywell RTH9580 Wifi. Neither unit has a C wire - I'm comfortable with the upstairs high efficiency unit, but the downstairs older unit has thrown me for a ...
1
vote
1answer
805 views

Need to add common “C” for thermostat; can anyone indicate where to connect it?

We just got a new WiFi capable thermostat that, unfortunately, seems to use a form of power stealing in order to charge itself. The problem here is that our house is actually quite well insulated; the ...
1
vote
2answers
402 views

Thermostat / Oil Furnace Question

I have an old oil furnace and I am looking for some clarification as to how it is supposed to work. It heats water filled radiators through out the house. Currently it is connected to a thermostat ...
1
vote
2answers
3k views

Which terminal should I connect it to for a “C” wire when none are labeled “C”? [duplicate]

I am looking to replace my old battery operated thermostat with a new wifi model. There is no "C" common wire connected to my old thermostat. There is a blue wire that is at the thermostat but cut ...
1
vote
1answer
712 views

How to wire a new Honeywell RTF6580WF thermostat to replace a Chronotherm IV?

I have an old Honeywell Chronotherm IV thermostat that I am trying to replace with a Honeywell RTF6580WF wifi thermostat. I have a gas furnace and an air conditioner. Wiring for Chronotherm IV ...
1
vote
1answer
815 views

How do I wire this thermostat?

Hello I have a Honeywell FocusPRO 5000 Non-Programmable 1 Heat/1 Cool Thermostat, Large Screen. The wires it needs are: Conventional Terminals: Rc 24VAC power from cooling transformer R ...
1
vote
1answer
382 views

thermostat c wire question [duplicate]

I am looking to install a new thermostat that will require a C wire. I have a single stage A/C unit and my current thermostat has Rc, G, and Y wires. There is also an unused blue wire which I traced ...
1
vote
1answer
628 views

Why isn't my thermostat clicking on/off automatically?

My thermostat is not clicking on/off automatically, I have called my landlord and they replaced a very old one with a brand new one and it is still not clicking on off automatically, but will ...
1
vote
1answer
526 views

Which wall should I install a replacement thermostat on?

I'm replacing an old thermostat that is behind a door to our dining room, that is usually kept open, hiding the thermostat. Given that the wires come from above and I have some flexibility as to ...
1
vote
2answers
25k views

Why won't my A/C turn on after I replaced the thermostat batteries?

Our thermostat died yesterday, but after replacing the dead batteries with fresh batteries, and confirming the LCD screen was operable, our AC no longer turns on. I have attempted a factory reset on ...
1
vote
1answer
677 views

How to balance thermostat settings between zones to maximize efficiency?

I recently purchased a house so this is my first winter in it. The house was built in 1939 so most of the house is on a single heating zone using hot water radiated heat. The radiators are cast iron ...
1
vote
2answers
1k views

How do I diagnose a thermostat and HVAC that intermittently doesn't respond?

My gas heater for the whole house does not follow the thermostat settings on some mornings. I have set it to 70 degrees at 6 am but now it is still 60 at 8 am. This happens weekly once or so and seems ...
1
vote
2answers
449 views

Is there a thermostat-controlled corn heater sized for a shop/garage?

I'm looking for a way to heat my 4-car garage. Two bays are for cars, one is for the mower and other items, one is my workshop. I live in Minnesota, with very cold winters, so a heater is necessary ...
1
vote
2answers
12k views

Why won't my heater turn off when it reaches my desired temperature?

My wife and I purchased our first home this past year and we did a bunch of repairs up-front via a rehab loan, and one of the things we replaced was a very old thermostat with a new digital one. I ...
1
vote
0answers
31 views

Keep finding thermostat on heat

On multiple occasions now, I have noticed odd things going on with my HVAC system, only to go to the thermostat and find that it has been set to heat! This happened once in the middle of summer, when ...
1
vote
1answer
384 views

Where can I connect the C wire on the A/C side?

I’m trying to replace my thermostat with the Honeywell Smart-WiFi thermostat. Quick summary, I have an extra yellow wire which I’m making the C wire, but its not connected at the other end and I’m not ...
1
vote
1answer
117 views

Zoned oil furnace and AC thermostat question

I recently moved into a new home and wanted to replace the old thermostats with digital Honeywell ones. From what I understand the home has a Rheem 10 Seer (1996) compressor and a Williams oil furnace ...
1
vote
2answers
127 views

Honeywell home ventilation system with no c wire for thermostat. How can I substitute the g for the c without blowing a fuse?

I'm hoping to get some help with my thermostat problem. We bought our home brand new and it came with a very basic thermostat (non programmable and runs on batteries). I want to upgrade it to a wifi ...
1
vote
0answers
124 views

Using a second thermostat to balance temperatures thru fan-only control

Like many others, temperatures between the two levels of my house are uneven. This is particularly noticeable as spring arrives and the upper floor (above ground) enjoys solar heating (so the heater ...