Questions tagged [thermostat]

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

264 questions with no upvoted or accepted answers
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Replacing my Honeywell thermostat with a Nest heatlink in the UK

Can someone help with this. Trying to pick the C wire and the NO wire from here. Please note I am in the UK
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How is an air handler's fan controlled if its control board doesn't have a G terminal?

Background I have a 2-stage cooling heat pump unit from Bryant, installed ~2006 (central Florida): Condenser model 698BNX048-B Handler model FE4ANB006 Shortly after moving in ~5 years ago, our evap ...
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Can someone assess my original thermostat's wiring setup?

This is a new world for me, I haven't messed with circuits since physics 101. When I watched a quick youtube tutorial on setting up my Nest E, I thought it'd be a simple "move wire in old C, to new C ...
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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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217 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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3k 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. ...
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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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47 views

Thermostat T694B replacing with Honeywell SuitePRO TB6575A1000

I am replacing a Thermostat T694B with a Honeywell SuitePRO TB6575A1000 in an apartment building with switchover heating/cooling, so presumably two-pipe system. Button-wiring mapping: Lo: 1 Med: 2 ...
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145 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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118 views

How does this wiring work?

I have a Trane XV90 and XL 14i. The wiring looks a little strange as in the picture bellow. _____________ | | BK W2 W1 R G Y B/C YLO O |___||...
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77 views

Tracing a dead thermostat wire conductor in wall

My home was rewired and remodeled in 2014 but I am finding out that the electrician did not run a new thermostat wire from my upstairs thermostat. I have a newer-looking 4-conductor wire coming out of ...
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HVAC is heating when thermostat is off

I seem to have a problem with my thermostat. I have tested the wiring of my HVAC system by wire nutting the the power (R, red wire) to the AC (Y, black wire), heat (W, white wire), and fan (G, green ...
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Thermostat not getting power (Nest E74)

I replaced an old Honeywell thermostat about a month ago with a Nest thermostat. Friday Nest started displaying an E74 error. I have two furnaces and two outdoor units, one for upstairs and for ...
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106 views

Connect “C” wire on boiler model number 1135-601

I've read several threads here and on the other websites but still can't figure out how to add C wire to my boiler wiring. I would like to replace my old mercury thermostat with Nest E or any other ...
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382 views

Can I calibrate this thermostat? (Cadet brand, 240V)

My thermostat operates but seems to be badly calibrated. It will hold temperature, and you can adjust that temperature, but its not the temperature it says on the dial! It goes much higher than the ...
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561 views

Honeywell RTH5160D Thermostat Wiring w/ Heat Pump

I have installed a Goodman heat pump and a Honeywell RTH5160D thermostat. I chose that thermostat because it is supposed to switch automatically between cooling and heat modes. The system has been ...
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49 views

New thermostat turns fan off when set to on, never turns off on auto

My oil heat furnace was functioning normally on an old mercury switch thermostat, but I wanted to replace it with a programmable Honeywell 5+2 one. There were Y, W, G, R, and B wires screwed in on the ...
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58 views

Thermostat wiring for ac

I recently installed a nest thermostat for our AC system. Unfortunately I was short sighted and just assumed all the wires were the color I needed. Since installing the thermostat our system won’t ...
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123 views

Will the existing wiring work with the new thermostat?

I am looking to upgrade my line voltage thermostat from a Dimplex mechanical thermostat to a Honeywell digital thermostat. Both thermostat has 2 wires on its back. Would the new thermostat work if I ...
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1k views

C-wire on Weil-McLain CGA Series 2

I have an old thermostat with only 2 wires connected to my Weil-McLain CGA Series 2 boiler. I would like to replace it with a Nest thermostat. I need to add a C-Wire in order for it to work. Luckily, ...
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2answers
149 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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2answers
354 views

Lennox G23Q3/4-100-2 And Ecobee4

**Pictures attached to go along with my rambling explanation I have my Lennox G23Q3/4-100-2 natural gas furnace and my central air system that has been working since 1995 on a basic programmable ...
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1answer
541 views

Installing a Hive Thermostat

I purchased a HIVE thermostat and want some assurance before I go about installing this. First of all i was wondering where to put the receiver as I thought it would just replace one of the ...
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1k views

Honeywell WiFi thermostat jumper loop separate ac and gas furnace

I need to validate my understanding for the installation of a WiFi thermostat that requires 24volt continuous power to operate in a constant state. I am DIYer who is computer literate. Like a number ...
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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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114 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 22....
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1k 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 ...
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1answer
141 views

New thermostat: How to wire it?

My old air conditioner thermostat broke down, so I bought a new one. But when it arrived, I was horrified to discover that the terminal of the wires were not named the same. Both thermostats have ...
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2answers
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Hooking up AC compressor to an old Lennox furnace

I'm trying to connect an ac compressor to an old Lennox G12Q3-110-3 furnace. Tried it a couple of ways and can either get the compressor to turn on or the furnace fan. Not both. Any ideas on how to ...
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15 views

Nest Thermostat wiring for heat pump

I am trying to replace my Honeywell Thermostat that is connected to a Honeywell EIM with a Nest Thermostat. I only have a 4 wire (G,B,R and W) ran from the EIM to the thermostat. My understanding is I ...
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2answers
45 views

I need a C wire connection for my new Glas thermostat

I have 3 wires(red,white,and green) going to my thermostat. I’m replacing my old thermostat with a new one the requires a C wire connection. The 3 wires goes to my Honeywell aquastat. The white goes ...
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Confused about HVAC wires

My townhome is using a heat pump and it's currently connected to a honeywell 3000 thermostat. I bought a gen 3 nest and from what I can tell, it's compatible. However, I'm a bit confused about my ...
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31 views

No Power to Thermostats - Even after Replacing

I changed my thermostats from Honeywell Smart TH6220wf2006/u Lyric T6 Pro WiFi to Honeywell T5 Programmable (NOT Smart) and couldn't get my furnace to push air out, but AC worked fine. A friend was ...
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Honeywell RTH9585WF thermostat behavior with heat pump and Emergency heat

I just installed a Honeywell RTH9585WF1012 to control my forced air furnace system which has: Cool: 1-stage heat pump Heat: 1-stage heat pump (same) + emergency gaz heat from furnace I have a fossil ...
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52 views

Is this blue wire in my A/C a C wire I can use at the thermostat?

Here's my current setup - separate A/C and boiler units. Some of the pictures may be confusing because the wires are differently colored than they're named, but I'm going by my actual thermostat. ...
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Connecting fresh-air damper to Lennox furnace OR replacing timer with new smart thermostat

We replaced a 20-year-old furnace with a new Lennox furnace and added air conditioning. The new system is still controlled by the 20-year-old Honeywell Chronotherm III thermostat. The furnace had (and ...
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53 views

Taco zone controller - blinking yellow light?

I have a Taco ZVC406 zone controller. This is the type which takes signals from multiple thermostats and uses relays to switch on the heating loop pump. I am using a Honeywell CT87K thermostat on one ...
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53 views

Web-based remote access of my Carrier Infinity thermostat and Flash end-of-life

I have a Carrier Infinity system, installed some 3 years ago. I was able to access the thermostat over the internet until very recently, because the web access feature uses the Adobe Flash Player ...
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Can I wire R from AC system and R from heating system to single R terminal on thermostat?

I want to replace existing thermostat that controls both heat and AC. There are two cables coming out of the wall. One goes to heating system with a red wire and a white wire, the other goes to to the ...
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181 views

Burning smell from AC vents after installing new thermostat

I was installing a new thermostat (ecobee3 lite Smart Thermostat, 2nd gen) to my AC unit (ARUF61D14AA). I opened my current thermostat and noticed that I don't have a C-wire (which is required for the ...
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1answer
226 views

Aprilaire 600M Wiring to Honeywell TH8321 Stat

Very rookie DIY guy here...I have installed an Aprilaire 600M but can't figure out how to wire it. My thermostat currently is using the U1 port for a normally-closed damper on a fresh air intake. I ...
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49 views

How is propane stove thermostat supposed to work? [Quadrafire Grand Bay DV40]

The home we bought came with a propane stove, with markings Quadrafire Grand Bay DV40. The stove is connected with a simple two-wire (non-powered) bimetal thermostat switch. How is the thermostat ...
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110 views

Problems w/ Nest

I've got a common problem but I can't seem to find the simple answer. My heating system is simple. Forced water oil boiler with three zones. Two zones are controlled by the Nest E Thermostat. I'm ...
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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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186 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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58 views

Two air handlers, one furnace, and an odd control system. What's the modern equivalent?

I have 2 air handlers, each has their own AC, and each of them have a hydronic heat coil that leads to one furnace. Air conditioning works well independently, but there's some weird controls when it ...
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29 views

Programmable Thermostat wiring Question

Existing thermostat is a Honeywell and has a separate connections for Aux (white wire) and E (Emergency black wire) The proposed Honeywell T'stat only has a single terminal labeled "Aux E". ...
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Upstairs is getting frigid at night during cool nights

I have a dual zone Lennox system, and it cools well, but for the past few weeks it seems to run away at random cooling the upstairs to several degrees lower than requested. We have EcoBee thermostats ...
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77 views

C Wire doesn’t work

Trying to swap an old Honeywell thermostat for new with Wi-Fi. Old thermostat doesn’t need C wire, but I have an unused blue wire in the wall. I installed the new thermostat correctly with the C wire, ...
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49 views

Are 8-Zone Wiring Centers Compatible With Smart Thermostats?

I'm looking at various wiring centers for gas boiler heating and I'm wondering if they're compatible with the major smart thermostats, such as Nest, Hive, and Honeywell. Wiring Centers: Reliance:...

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