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Questions tagged [nest]

The Nest is a programmable, internet-enabled thermostat

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What terminal to use on AC for C wire / nest dual transformer install

So i purchased a nest gen 3 and proceeded to install it. This is on a dual transformer system, separate boiler and AC system. The good news was i had a unused G wire on the Heat side that I was going ...
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1answer
33 views

Connecting Common Wire from thermostat to Air Handler

My apartment has a central heating/cooling HVAC system consisting of a gas-fired hot water heater which feeds hot water to a First Co air handler for heating, and a rooftop compressor which feeds ...
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2answers
144 views

Nest thermostat E74 error - no power to Rh Wire

It was working with no issues for last 3 years. Today it suddenly showing this error. Any help appreciated.
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46 views

Central Heat Won't Turn On When I Raise the Temperature on Nest Thermostat

I'm sure my heater is working. It's 47 degrees outside, and I'm only a little cool inside. My Nest thermostat is set to 67 degrees. The screen on my app (which agrees with the thermostat) is shown ...
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17 views

Nest E without common wire stuck in purge loop as soon as the Rheem heat furnace ignites

I have a honeywell hz432 and just installed a few NEST thermostats with a common wire and they seem to run fine. I added another NEST E thermostat, but this one didn't have a common wire, and when it ...
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71 views

How Do I Wire My Nest Hello Doorbell With A Plug In Transformer?

I wired up a nest hello doorbell to my existing chime. It rings fine but lacks enough power to operate properly. That’s ok, it was a little expected. Unfortunately, changing the old transformer is ...
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22 views

Intelligently Controlling 5 PTAC Units

I recently purchased a new apartment which comes with GE zoneline PTAC units that control both heating and air conditioning electrically. There are a total of 5 in my apartment, 1 for each bedroom and ...
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91 views

Adding C-Wire for Nest to Triple Aquastat Relay L8148J

Need some extra eyes and advice on how to add a common wire to our current boiler setup. We have a Triple Aquastat L8148E that has 2 wire that connect to our thermostat. Like many before me, I'm ...
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85 views

Nest 3rd Gen 24VAC two transformer issue

Hopefully this will finally solve the issue with my Nest. I bought a Nest 3rd Gen Learning Thermostat and followed the instructions to the tee. I have a two transformer system (Forced Air A/C and ...
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26 views

Fan Blows Constantly Even With C Wire

Nest stated that my furnace only set up (we have an evap cooler) would work with their Nest E product. I self installed only two wires, R and W. The heating works; however, the fan always blows ...
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47 views

Nest thermostat installation to furnace and heat pump

We have T874G1196 thermostat by york (can only find honeywell documentation) MB7BM-1200K-B air handler H8HK015H-21 electric heater Thermopump (heating and cooling) We want to connect it to a nest ...
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1answer
26 views

How do I add a Venstar Add-A-Wire to my Lenox G12D2-82 furnace?

So I have a Nest Gen 3 thermostat and I am in need of a C wire. I have a Lenox G12D2-82 furnace. I have 4 wire set up. The Venstar makes 4 into 5 wires. I have a fan heat cool and power wires. There ...
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76 views

Can I just extend this blue wire in furnace for Nest thermostat?

First time doing this, don't want to burn house down. The brown bundle is coming from thermostat, the white bundle I suspect is coming from A/C unit. Do I follow these steps? Find a scrap piece of 18 ...
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33 views

How to identify a c wire?

I have 3 wires coming out from the wall at my new house (red, white, blue). It is a water boiler heat only system. The tstat was already removed unfortunately. I thought the blue wire was the C wire, ...
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0answers
33 views

Thermostat has two wires going into C terminal

Trying to help my dad install his new Nest thermostat - for some reason his thermostat has two wires going into the C terminal. I've searched and cannot find any other question about a setup like ...
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42 views

Can a Nest work in my setup (or am I stuck with Lyric, as they claim)?

Before crucifying me for the subjective question let me clarify that my question is quite specific if you read on. I bought an old home with bad insulation and a 55-year-old furnace 3 months ago. I ...
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17 views

Need C wire for Nest thermostat with zones. From zone panel to thermostats?

If I have a C wire connected from the furnace to the zone panel (but not to the thermostats), do I only need to run new C wires from the zone panel to the thermostats?
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61 views

nest 2nd gen, no common wire/terminal in the fan coil unit

I'm trying to install an older nest in my condo but it immediately complains that there's no common wire attached (error e24). I opened up the fan coil in my condo and there is no specific terminal ...
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25 views

I have 2 wire going into R, how should i connect to nest?

I'm installing a Nest thermostat: How do i connect the blue and red wire? Nest tech said i have two transformer.. do i split them into RH, and Rc?
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72 views

What powers a Nest thermostat? [duplicate]

I have an older thermostat I'd like to replace with the more modern Nest thermostat. The online Nest compatibility checker tells me that I have a compatible device. However, I'm not sure how it could ...
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41 views

How can I use home automation with hot water heating radiators?

My apartment (in a condo building) is currently using stationary PTACs (using electricity and hot water), which I'm planning to replace with a split-level A/C system (for cooling) and hot water ...
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37 views

Honeywell Thermostat to Nest E Dehumidification

I am trying to replace my Honeywell Prestige IAQ thermostats. I noticed that my downstairs thermostat has a dehumidification option (upstairs shows no such option). I checked the wiring at the ...
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1answer
311 views

Door bell partially rings randomly since Nest doorbell installation

(Somewhat related to this unanswered question: Doorbell constantly rings even after replacing switch but not an exact duplicate) My house had a modern wired doorbell (wired using Cat5e, if it matters)...
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1answer
29 views

Is this circuit correct for controlling old 750mv HVAC with NEST

I am just starting out with wiring and some other home improvements. Decided to install a Nest 3rd generation thermostat. I had a TH5110D Honeywell thermostat, so I pulled it out and found 5 wires ...
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2answers
97 views

Installing Nest on Viconics P117 Board

I couldn't find any help on forums or websites if anyone may have tried to install Nest by replacing old Viconics P117 Board and E117 thermostat. I have an Electric Furnace and Heat Pump configuration....
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1answer
44 views

Upgrading from a two wire analog tstat to a Nest, need help

I am looking to upgrade from an old analog tstat to a Nest. My old stat had only two wires connected (R and W) but the wire bundle had three. So I tried connecting the green wire to C and then turned ...
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71 views

Nest Thermostat E and OpenTherm

On nest.com it's possible to find out that the 3rd generation Nest Learning Thermostat supports OpenTherm protocol to communicate with a central heating boiler. Does the cheaper (and the very recent) ...
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96 views

Need to identify a common wire on my old HVAC

For Nest Thermostat 3, I am trying to identify a common wire on my old HVAC. The diagram can be found on the link below:
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145 views

How can I tell if my furnace common wire is “properly grounded”?

I've been experiencing occasional short cycling of my A/C compressor (turns on/off quickly several times in a row) and Nest senior support is speculating that my common wire may not be properly ...
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1answer
73 views

Which terminal should I connect it to for a “C” wire on an american standard AM4A0A30

I'm trying to connect a 3rd gen Nest thermostat. I have a 2 zoned heat and 1 zone AC. The zone with this thermostat has a boiler wired Rw, W1 and HVAC wired Rc, G, Y1. It's summer so I'm only using ...
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1answer
41 views

Improve HVAC in single upstairs room with vaulted ceiling

Setup: Our house is a two-story built in 2011. We have zoned HVAC off a single unit with electronic dampers. The upstairs has three bedrooms and two bathrooms. The master bedroom is the only room ...
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1answer
539 views

Does the Nest thermostat automatically change modes?

I understand from the Nest website that the thermostat has heating, cooling, and heat/cool modes. I also know that over time Nest learns your preferences based on how you adjust the thermostat, and ...
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164 views

Nest for this setup

Is this the correct wiring setup for nest.
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1answer
56 views

Nest thermostat to Kelvinator furnace

My old thermostat had 4 wires. I replaced with a Nest thermostat. At times the AC condenser is running but the furnace blower is not running. Found other with this and they said need to add common ...
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1answer
607 views

Nest Doorbell not ringing indoor chime

I recently picked up the doorbell from Nest, the Nest Hello and set it up. One issue that I'm running into is what wires should be used when trying to make it work with the indoor chime. The ...
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1answer
277 views

Adding Unused C-Wire for Nest Thermostat

I'm having an issue with my NEST thermostat short cycling my air handler fan while in running AC. This is a known issue, and the fix seems to be adding a common wire to the NEST. My thermostat is ...
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52 views

Gas boiler turning on when Nest says hot water and heating are off

We had a Nest installed at the end of April. Currently we have a problem where the boiler is turning on even though the Nest is saying heating and hot water is off. I have turned off eco mode and ...
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1answer
4k views

Can I install a nest thermostat on a 2-wire boiler (with unmarked wires)?

Our house has an old boiler, and the thermostat isn't working. I'd like to replace it with a Nest thermostat. But, when I took the cover off to check which wires it had, I only see two wires (red and ...
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2answers
5k views

Nest Thermostat - Not cooling

First warm weather using my nest thermostat and now trying to use the central air. However, only the fan turns on and it doesn't actually cool no matter how long I run it. (It worked perfectly in the ...
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1answer
2k views

Nest, Blue Wire, W1 and W2

I just got a Nest E thermostat and I'm trying to hook it up. There is a blue wire that I had assumed was the "C" wire, but looking at the furnace, it doesn't look like that's the case, as the blue ...
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1answer
424 views

Is my Nest thermostat wired correctly?

I've been having issues like the heat pump not heating. Now that it's hot outside, my A/C isn't working. Can someone tell me if my Nest thermostat is even wired correctly? If it helps any, here is ...
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2answers
258 views

Nest E Thermostat Power

My thermostat is in the basement, connected to a Honeywell R845A to run a circulating pump for heat. I bought an Nest E for the main house and it works great. I want to replace the thermostat in the ...
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207 views

Nest + opentherm + zone valve

I have a Nest 3G, I'm now considering to change my boiler due to age-related issues. Can someone tell me if I can connect the Heat-Link to both zone-valve (on/off contacts) and boiler (OpenTherm). I ...
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0answers
54 views

Smart Thermostat (Nest, Honeywell or Ecobee) from KMC wiring?

I moved into a 1br condo recently and was looking to update the thermostat to Nest (or other Smart home thermostat). The current thermostat model is KMC and when I took off the casing, the wiring does ...
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1answer
28 views

Bedroom Radiator not operating properly

We have two nest thermostats installed over a month ago and i am not sure the issue was after or before the installation of nest thermostat. We have two zones of heating installed in our house.One is ...
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1answer
1k views

Add-A-Wire - COMMON / C Wire to a 3 Wire Thermostat

I am battling a Nest and losing at every turn. I have a 2 zone system and was able to install a Nest on the 1st floor by repurposing a wire as a COMMON wire. Unfortunately, the 2nd floor only has 3 ...
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1answer
517 views

Nest E thermostat on ancient 2-wire Bryant boiler system with 2 zonesq

I have a 2-zone hydronic system running off an ancient Bryant boiler. Power is supplied by a 24V transformer, and each red wire passes through a Taco zone valve before heading off to the appropriate ...
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3answers
314 views

Is it normal for my boiler transformer to show intermittent drops in voltage?

Since I installed a Nest-E I've seen my Weil-McLain boiler cut power to the R-wire and C-wire intermittently. Voltage drops to nearly 0 and the Nest-E errors with E-195 no power. Other times ...
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0answers
753 views

Need Help on Adding a Common Wire for Nest

I recently purchased a Nest thermostat. After couple weeks of usage, the Nest is constantly shut down due to low battery. I search online that adding a common wire is the go solution for this. However,...
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1answer
2k views

Gen 3 Nest not charging suddenly

I installed a nest thermostat a month ago. A very simple two wire install for a boiler. It worked fine without any issues for a month. This morning I went to adjust the temperature remotely and was ...