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
42 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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0answers
16 views

Why would one of the zones of my Slant Fin gas fired hot water baseboard heating system not be heating?

Thus far I have: replaced with new batteries. turned down temp and switched the breakers turned heat back up, no response Can a pilot be out for one zone? The other two are warm and cozy. Did ...
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0answers
9 views

How do I wire a Honeywell ultrastat TB7220U for second stage cooling?

Has anyone wired this commercial thermostat in before? Honeywell TB7220U ultrastat I had needed to know about the 2nd stage cool wiring set up -y2? And changing the wiring correctly for install ...
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1answer
53 views

Do I need a 24V or 120-240V thermostat?

My Honeywell thermostat just broke. I want to get a new one and install it myself but I don't know whether to get a 24V model or a 120-240v model. There is no indication of this on the one I have. How ...
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1answer
275 views

Where do I connect the C wire in my furnace?

I am upgrading my thermostat to a Nest, and would like to add a common wire. My current furnace controller doesn't have a C terminal, but the current thermostat wire has 2 unused wires (black and ...
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2answers
437 views

No electricity going to thermostat

Our old thermostat is working but I want to change to a new one (nest thermostat). I have two exact HVAC unit at home. I change one it works but when I change the second one it doesn't work because ...
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0answers
25 views

Can't find the circuit board of my HVAC system

I'm trying to install a wireless thermostat for my church building's HVAC system. Currently there is no C wire, so I tried to see where the circuit board was so I could install one. I couldn't find ...
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1answer
502 views

Please help establishing a C wire for new tstat

I bought a new WiFi tstat as a replacement. The tstat controls my second floor hot water baseboard heat and my central air conditioning. I've located all the wires....the ones coming up from the ...
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15 views

New Furnace won't turn on after trying to install thermostat

I had a furnace installed about a year ago in my basement. The installer left the wires sticking out of the wall for me to install a thermostat. He said if you want to turn the furnace on, just ...
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1answer
35 views

thermostats for high desert climate

We live in Spokane, WA, a high-desert climate. We don't need a programmable thermostat, but we do need one to keep an constant ambient temperature range. This may mean A/C during the day, and heat at ...
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2answers
42 views

Which furnace thermostats support variable swing/deadband?

My home furnace is currently controlled by a programmable Honeywell thermostat, but it regularly thrashes the furnace by turning the furnace on for just ten or twenty seconds. It seems that the ...
2
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1answer
1k 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 ...
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1answer
472 views

How can I add a C-wire to a Venstar T5800 thermostat?

I am trying to replace my existing thermostat. My old thermostat has: Rh, W (coming from the heating unit). Rc, Y, G (coming from the AC unit). On the Venstar T5800, I can map as follows: Rh+Rc ...
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2answers
177 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 ...
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1answer
756 views

why does my heat pump wiring diagram show 7 wires going to the thermostat but the thermostat only says it needs 5?

Here is a link to the wiring diagram for my heat pump. The thermostat that I am planning on buying has the following terminals C, G, Y, O/B, RC, R, Aux, E, and L. The instructions say to jump the RC ...
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1answer
355 views

Can I replace this Airwell thermostat?

I am in market to replace my simple A/C control unit with one that integrates with home my z-wave based home automation system. However, before I make the splash and buy a compatible thermostat, I ...
0
votes
1answer
197 views

How can I replace an old dial thermostat on an oil furnace with Hydrostat 3250 Plus?

I recently bought a home with an oil fired Biasi furnace that has a Hydrostat 3250-Plus attached. It uses an old analog round dial thermostat, and I'd like to replace it with a new digital (wifi) ...
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3answers
262 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
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1answer
34 views

Updating thermostats to single system

I have a three floors in my house, each controlled by it's own thermostat (separate air handlers and mechanical valves on furnace). Baseboard heat. The three thermostats are controlled separately, ...
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1answer
49 views

How to troubleshoot heat that's always on?

My boiler (Weil Mclain CGA Gold ~2003 install) failed the other day. After some help from a plumber and reading the manual, I replaced a few parts (more below) to get it running again. Now one zone is ...
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0answers
108 views

How can I tell if C wire is active and connected to Thermostats?

We are trying to install a smart thermostat (Ecobee 3) so we are in need of a C wire from our boiler. We see a green wire in the wall, but it's not connected to our thermostat currently since it ...
0
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1answer
379 views

Where to add C wire on this air handler?

Thanks for helping me here. I am adding a new wifi thermostat to my system but need to add a C wire directly to the air handler (system is a First Co air handler with hot water boiler for heat and ...
0
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1answer
462 views

Where is my common wire on the unit?

I have 2 systems in my house, my heat is gas hot water radiator heating and A/C is a separate newer system. I'm trying to figure out if I can run a C wire off air handler from the A/C system to run ...
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0answers
14 views

Can I use the following parts to create a remote duct temperature sensor for my thermostat?

Parts: DS18B20 Temperature Sensor (PDF) or TMP36 Temperature Sensor (PDF) Cat5 cable Would those parts make a viable replacement for a remote duct sensor replacing a Venstar Remote Duct Digital ...
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0answers
19 views

Can you hardwire a residential through wall A/C to a 3H/2C thermostat?

I have a boiler with radiant baseboard throughout my home with four zones of heating and two through wall air conditioners and Aprilaire 350 Humidifier. I am upgrading my thermostats to the Honeywell ...
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1answer
201 views

Why did I have to change the wiring to use a smart WiFi thermostat?

I just installed a Emerson Sensi wifi thermostat.It works, and I ran a separate C wire. I had a 24 volt 5 wire Robertshaw programable thermostat that ran my boiler, air handler and AC. It is all ...
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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 ...
2
votes
2answers
8k 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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0answers
42 views

Why won't my thermostat control the HVAC anymore after trying to switch thermostats?

I bought a new Nest thermostat which is supposed to be compatible but needs a professional installation (advice that should have been heeded by non-professional electrician me). This is to replace an ...
0
votes
2answers
52 views

Is there any risk of running both the fan and furnace at the same time?

I am attempting to build my own thermostat using an arduino and a few relays and have been trying to map the appropriate wires so I don't damage my furnace/AC unit. This is a picture of my ...
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0answers
18 views

What type of control systems are available for a home with multiple HVAC systems?

Our new (used) home has two HVAC systems, one for upstairs and one for down. There is a thermostat in the dining room, which is directly affected by sun. And one in our bedroom, that clicks all ...
2
votes
1answer
232 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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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 ...
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3answers
13k 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 ...
0
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1answer
77 views

Connect Taco Radiator system to a new Honeywell wireless thermostat

I have a Taco model 572 valve connected to an existing wired Honeywell TH8110 thermostat for my oil fueled radiator system. I'm getting a new Honeywell TH6320 wireless thermostat for a new A/C ...
0
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4answers
5k views

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

I Purchased the Honeywell WiFi Prog Thermostat to replace my Round Digital Honeywell Thermostat. I have separate Heating and Cooling (Heating is a Weil McLain Boiler for Hot water baseboard and Hot ...
0
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1answer
249 views

How to add “C” wire using a/c fan wire?

Honeywell has a video that shows how to use the fan wire ("G") of the cooling system as the "C" wire for the thermostat. It is in the video - "Honeywell DIY wifi...substitute g-wire for c-wire" on ...
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0answers
78 views

Can I use the T terminal in my furnace as the C for a Wifi Thermostat?

I've read many posts on this, and believe I know what to do, but want to make sure. My furnace (a Lennox G14 Series) does not have a C terminal which needs to be connected to the C terminal in my new ...
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0answers
26 views

Why are certain radiators hot during the night when the thermostat is very low?

We have a gas central heating system and we have set the thermostat to come on at different temperatures during the day. Generally between 7.00 and 22.00 it is set between 19 to 22 centigrade. From ...
0
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1answer
48 views

Possible to check NEST system compatibility by looking at current thermostat model?

I'd like to replace my Honeywell CT87A thermostat with a Nest thermostat. I see that Nest has a page to check system compatibility. Is it possible to identify if my system is compatible without taking ...
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votes
1answer
103 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 ...
3
votes
1answer
289 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 ...
2
votes
3answers
7k views

Are there any ductless mini split systems that offer standard HVAC wiring controls?

Have been looking for in the US a ductless mini split heat pump system something like the Mitsubishi Electric Mr. Slim that uses a non proprietary wiring scheme for its wall mounted thermostats. ...
0
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2answers
109 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? ...
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1answer
24 views

Wall mounted dial thermostat

I recently bought a wall thermostat I broke the plastic front on the box to remove The thermostat as I tried to pull it out of the box the dial came off in my hand and I do not know where it ...
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0answers
35 views

Thermostat needs to be set very high to work

Our home thermostat is behaving strangely. Let say it shows that the current room temperature is 60F. If we set it to 63F it will start the Fan (ventilation) but will not actually start the heating so ...
3
votes
3answers
9k 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 ...
3
votes
1answer
5k views

Convert line voltage heating system to use low voltage thermostats

I currently have two line voltage ceiling radiant heating systems in my condo each with their own DPST thermostat. I'd like to use low voltage thermostats such as the nest. I found this ...
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1answer
57 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 ...
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0answers
14 views

Zones and setback thermostats

I've got a two-floor house, forced-hot-water and traditional radiators, with a thermostat and zone for each floor. I'm working from home at the moment, so the ground floor is set up to be "office ...