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
968 views

Heat pump only running above 35 degrees

We have just moved into a house with a Lennox XP17 heat pump. It has two stages of electric heat strips in addition to the heat pump. In observing the power bill, I have been astonished at the ...
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1answer
104 views

Just installed aprileaire 700 whole house humidifier. Furnace takes air from outside

I installed the humidifier on the supply plenum and digital guage on return as instructions showed. I have a furnace that draws outside air into the return duct. This is a new construction home and ...
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1answer
783 views

What wire should be used for modern thermostat

I may (or may not) be pulling new wires to support current-generation thermostats.... Upgrading the thermostats themselves seems a good time to upgrade the wire too, though I think I could get by on ...
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1answer
976 views

Controlling separate heat and AC units from a single thermostat

I currently have central air in the attic and furnace in the basement for the heat (steam radiator heat). I have both wires run to the same location but have two thermostats. Can I wire them both to ...
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3answers
19k views

Figure out if I have gas or electric heating

I have a year 2000 house in Bay Area California. The Honeywell RTH2520 thermostat that came with the house doesn't work anymore because the metal things on the side of the AA batteries became aqua ...
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4answers
4k views

Connection for C wire on Mastertrol Mark V zone control panel

I have spent hours searching the web for information on this 20+ year old zone control panel, which supports 3 zones of Heat and A/C. The thermostat I'm replacing (on Zone 3) connects to T4/T5/T6 as ...
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1answer
2k views

Does it matter which 24v line I use to splice a common wire from?

I have a RayPak boiler that currently has a W and R wire only. In wall i have a 5 connector thermostat cable so I have three extra wires I can connect to. I'm a little unclear if it matters if i ...
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0answers
2k views

Why does my gas furnace run once then wont come back on until reset when temps are below 30 outside? [closed]

My gas furnace will run one cycle and then not come back on until the switch is reset. Once the switch is reset it will kick on immediately run once and again I will have to reset before it will kick ...
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161 views

Why does my non-vented gas fireplace turn off after a few minutes?

I have a non vented gas fireplace, brand new, it has a screen on the front and logs. The pilot light is strong and stays lit, however the main flames turn off after a few minutes even when the ...
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1answer
58 views

Thermostat installed, but why also install a separate timer?

Our home is 8 years old. We always assumed the thermostat didn't work so we ignored it, but a plumber came to remove air bubbles from our radiant heating pipes and told my wife he thinks the ...
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1k views

Honeywell TH6110D1005 Thermostat keeps resetting itself

I have a Honeywell TH6110D1005 thermostat. I do not use the program mode, I keep my temp set to 71° at all times when it is on the Cool setting. Sometimes, it resets itself to 65° for no reason ...
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3answers
15k views

Thermostat wiring splice

I need to relocate a thermostat and have the additional wire needed but I am not sure of the ideal way to "join" the cable sections. Will using wire nuts and zip tie be good enough?
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79 views

What is this device connected to my HVAC unit?

I have this device connected to my HVAC unit in my apartment. I only have it in two of my rooms. In one of the other rooms I do not have this unit and was able to install an ecobee seamlessly. However,...
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1answer
3k 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 ...
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1answer
6k views

Electrical Outlet - Red and black wire to L1 T1

Background: I removed an in line wall heater thermostat from a 120v outlet, and want to ensure I reconnect the wires accurately. Question: A google search hit insists the wire marked in red is ...
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1answer
59 views

Can 7 day programmable thermostats typically be programmed with each day the same without having to duplicate?

I only need 2 settings for my heating, one for night and another for day since we're basically at home all day every day. We have a ground source/underfloor setup which was designed to run primarily ...
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2answers
269 views

parallel thermostat

I have a venter room heater in a cabin. It uses a milivo;t thermostat. I am hooking it up to a wifi thermostat using a relay and 24 volt power supply. My concern is that if the power goes off that the ...
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1answer
395 views

How to reduce temperature difference between the second floor and basement?

I have one thermostat on the second floor and while it is achievable to get a desired temperature on the second floor, the basement is always cold.
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63 views

Why Does My Heil Furnace Start When It Should Be Off?

My Heil furnace starts with the thermostat set to off. I disconnected the thermostat wires at the thermostat and it still starts randomly. I disconnected the heating wire at the board and it still ...
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2answers
8k views

Can I run my furnace in fan-only mode without a G wire?

The house I bought has a programmable Honeywell furnace. It only has a 2 wires connected to it - a black wire and a white wire. The heating system is working fine, except that when the heater is not ...
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1answer
152 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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0answers
151 views

C Wire in HVAC Unit

I am looking to install a new style thermostat in my apartment and it requires a C wire. I do have an extra wire run from my HVAC unit to where my thermostat is. But when tracing it back to my HVAC ...
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5answers
4k 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 ...
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1answer
72 views

How can I add “smart” functionality to an old thermostat?

I recently moved to an apartment, and my roommate and I were talking about how much better it would be if we had a smart thermostat. We're going to ask the landlord about an upgrade, but I thought I ...
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1answer
1k views

Replacement thermostat wiring for new Honeywell Wifi model

I moved into a home recently and found the old thermostat temperature controls to be inaccurate at turning on and turning off A/C as set so I purchased a Honeywell RTH6580WF thermostat as a ...
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1answer
2k views

How to find the right thermostat for my gas fireplace?

I have a Superior SSDVR3530CNM gas fireplace, which I'm trying to find a proper thermostat for. The manual recommends this one: However, it doesn't seem like they are sold anymore. (Or I'm not ...
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1answer
73 views

Please help me! [closed]

When setting my programmable thermostat should the 'heat to' or the 'cool to' setting be higher? Please ask me if you need any more info to answer this question
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1answer
373 views

Added a new 5th wire for my wi-fi thermostat, now where to connect it?

4 wires at thermostat: R G B W (red green blue white) 5 screws at furnace: G C W Y R Single-stage gas furnace with A/C unit The home's previous owners kind of did everything in a very make-shift way. ...
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2answers
2k views

How do I make a 110V fan turn on when the thermostat turns the AC on?

I have installed a new a/c with thermostat...easy enough, but thought to add a fan to the mix. Basically, I'd like to add a fan to increase ventilation into a second room that would turn on whenever ...
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0answers
344 views

Installing new thermostat without a C wire. Can I use my heater/R wire instead? Random 13V as well

I'm installing a thermostat, but I don't appear to have a C wire. My old thermostat had R/RH,Y,G,and W. It's an AC system that was setup before I got here. The actual AC unit is a long way away and ...
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1answer
811 views

wiring two thermostats in parallel [duplicate]

I wqant to add a wifi thermostat to a millivolt system. I would like to keep the current thermostat in case of power lost so that it would kick in at a minimum temp say 45 degrees. How do you wire a ...
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2answers
5k 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 ...
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2answers
881 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 ...
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1answer
17k views

Wireless Thermostat C-Wire Substitute

I've read How can I add a "C" wire to my thermostat? and checked out the Venstar Add-A-Wire Accessory. I've watched Honeywell's YouTube video on "DIY Wi-Fi Thermostat Substitute G-Wire for C-Wire," ...
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1answer
330 views

HVAC Fan Set to Continuous By Landlord- Please help me rewire

I live in an apartment in which the landlord has set the HVAC fan to be continuously blowing even with Auto Fan setting on. Fan will also blow when Thermostat is turned off. Please help me rewire ...
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2answers
94 views

Is it safe to replace the thermostat when furnace is shut off?

I need to replace the thermostat in my basement. It is an old style round shape Honeywell mechanical non-programmable thermostat. The gas furnace is turned off (The switch is at OFF now). Is it ...
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0answers
53 views

Added load to thermostat circuit?

I have a couple Nest thermostats that I want to power when my boiler is powered off. My plan is to hook them up to a 24v transformer using the existing R/W wires (no C wire and I don't want to run ...
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2answers
2k views

Can the cooling wire (Y) be used to activate the furnace fan with a programmable thermostat?

Simple question I think, but you guys make the call. Can the cooling wire (Y) be used to activate the furnace fan? My neighbor has a Honeywell RTH7400 programmable thermostat used for natural gas ...
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2answers
103 views

C wire - Where does it go?

Got a wifi thermostat. Behind the old thermostat was a blue wire. The other side of the blue wire in the equipment isn't plugged into anything. I need to get the 24v common hooked up to this blue ...
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1answer
2k 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 ...
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2answers
595 views

My furnace has a vibration for about a second at the end of the heat cycle.

It runs fine for the approximately 15 minute heat cycle. It appears as though it happens as the thermostat is satisfied and the gas valve shuts off. The vibration is heard upstairs and throughout the ...
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2answers
455 views

Zoned thermostat in every bedroom

I am getting a new AC and coils new use old one died This is for second floor where we have 4 bedrooms Question Is it possible to have thermostat in every bedroom Is it allowed under code ? What ...
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1answer
2k views

Multiple C wires? [duplicate]

I recently received a wifi enabled thermostat which I thought I could install easily since I saw an unused wire (Blue) which I assumed would be the C wire behind the current thermostat. When I went ...
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0answers
2k views

Trane Weathertron Stat to Honeywell RTH2510

I have a Trane Weathertron thermostat thst I am replacing with a New Honeywell RTH2510. This is a heat pump with auxiliary electric heat. The wires on the Tran thermostat are. R, T, O, G, Y, B, X2 ...
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0answers
636 views

Adding a C wire

I know this question has been asked multiple times and I'm going to try some of the methods I have read in other threads but wanted to ask this question since I didn't see anyone else's wired the way ...
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9answers
282k 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 ...
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1answer
857 views

Can I easily add a thermostat to a whole-house fan?

Is there a straightforward way to add a thermostat to an existing (basic no-frills) whole-house fan? I'd like to be able to set it to shut off when the outside temp rises to a certain point--so that ...
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1answer
896 views

How to wire A/C Thermostat given different wiring conventions

I've just moved to a new apartment in which I'd like to replace the current central A/C thermostat with a new one with WIFI control. I hope it's possible! I have basic diy electric skills but no ...
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0answers
2k views

Is Nest 3rd Gen Thermostat compatible as a replacement for Honeywell TH3110D1008

I have an Ultra-Zone EWC-ST-2E controller unit for my gas AC unit at home (heating and cooling). It is set for two zones. Where the first zone has to be on (heating or cooling) in order to enable to ...
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1answer
437 views

How to Change Chinese HVAC Thermostat

I am looking to put Nest thermostats in the house, I have now found out my entire house (one in each room, 6 of them) has been wired with HVAC Chinese U12A UNIVERSAL A/C CONTROL SYSTEM urrgh – they ...

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