Questions tagged [nest]

The Nest is a programmable, internet-enabled thermostat

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125 views

Nest Thermostat says “delayed” and never turns AC on

New Nest, replacing an old thermostat. Image of old setup: Nest setup: The Nest says "cooling" with the blue screen for about 1 second, then switches to "delayed", then just ...
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1answer
46 views

Where to connect C wire if no C terminal

Hi wanting to connect Nest and want to install a C wire. HVAC only appears to have G,W,R so not sure where to connect C.
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1answer
37 views

Connect separate Heat / AC systems to a Nest E

I have oil/hydro zoned heat, and a separate AC system. I have Honeywell ProSeries thermostats that have some 16 wire connectors (apparently designed to handle a nuclear power plant or something). I ...
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2answers
55 views

Nest thermostat causing condenser unit contactor to chatter when NOT calling for cooling

I have dual transformers, separate heating and AC. I've recently installed a nest learning thermostat (3rd gen). This is my wiring. The c wire comes from the the transformer on the AC side (pairs ...
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49 views

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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17 views

Rewiring for Nest Thermostat - Current ABCD Configuration Carrier

So I would like to use a Nest thermostat on my carrier system. I have the ABCD wiring configuration from current thermostat to the board on the furnace. On the attached image, you'll see three brown ...
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0answers
63 views

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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11 views

Carrier fb4cn030 with nest

Looking to hook up my AC to Nest. Old thermostat had VG and V+ at thermostat.i ran new 5 wire from unit to nest. I believe I need Y1, G ,RC but where do I get it from my unit. I see there's an ...
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23 views

Baystat240 to Nest

I’m trying to install a Nest thermostat. I currently have a Baystat240 installed. I have a heat pump with electric emergency heat. Can you tell me which wires will go where on the new nest? [![enter ...
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1answer
165 views

Why is Thermostat Y wire connected to C terminal on furnace?

I have a Nest E thermostat, and like many others have lost wifi and getting low battery because I have no common wire connected. After looking at my old Lennnox 78ugf3-75-1 furnace, I noticed that my ...
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25 views

Google Nest doorbell install - 6 wires

I’m trying to install a nest video doorbell, however I’m unsure how to wire it up as I cannot find a relevant wiring diagram. I have a Friedland 106 doorbell with one doorbell button at the front door....
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2answers
33 views

Trouble with identifying wiring for heat pump setting up Nest

The home I moved into has a Honeywell thermostat controlling an Amana heat pump. I am trying to replace this with a Nest thermostat instead. Here is a photo of the wiring for the existing thermostat ...
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1answer
78 views

Installing a Nest thermostat without a C wire?

I am attempting to install a nest but do not have a common wire on my hvac unit, perhaps it is slightly dated. I have read that on older units the O terminal is the same as C and I can remove the ...
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4k views

Doorbell transformer is this it?

I am going nuts trying to find my doorbell transformer. Someone suggested it may be this. But doesn't look like one to me. Is it? If not any suggestions where it may be?
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1answer
77 views

No power coming from c terminal on furnace

I am trying to set up a nest. My system was a simple heat only R/W wire set up. I attached the green wire to the c terminal on my furnace, but no power is being fed from it, or at least the Nest is ...
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1answer
77 views

How do I wire a/c if furnace wiring compartment has no y terminal?

I have been trying to figure this out for more than a year. All was running until HVAC company came to replace 2 thermostats with nest and rewired 2 HVAC units (a front of house and a back of house ...
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1answer
57 views

Checking my understanding - How to add C-wires for smart thermostat install x3

I'm in the process of installing some smart thermostats (Nest Thermostat E) to replace my old ones. I have a boiler radiator heating system with three zones. Two zones are straightforward heat only (...
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34 views

Intermittent Furnace Issue

So I have been having a bit of an issue with my furnace since installing the nest thermostat. The first day after I installed it was perfect. Everything was working. The second day I kept getting the ...
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0answers
32 views

2 humidistats for 1 humidifier

I have two zones in my house with a damper system and want to move away from using my humidistat to control the solonoid valve on my humidifier and instead use my Nest thermostats. My zone control ...
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2answers
703 views

One of two Nest Thermostats won't run Fan Only, fan runs with heat though

We've got two Nest Learning Thermostats (3rd Gen) running two separate heating and cooling units in an office. They both work fine for heating and cooling, with one exception: one unit will not turn ...
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1answer
43 views

Add “C” wire to NEST

I have a NEST thermostat. My heating and cooling system is in the attic.I need to add a "C" wire to the control board, but I can't find out where I need to open the unit in the attic to see where the ...
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27 views

Nest Thermostats: Balancing temperatures between zones

So, I'm wondering if there's a way that I can program my Nest thermostats to help moderate temperature disparities between my first and second floors. Here's the situation: I have forced air from a ...
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1answer
126 views

Can I use a nest thermostat for two heating sources (Furnace and electric floor heating)

Current situation: My home is currently heated with central air. Not my first choice, but that's what I have. I have brand new 98% efficient modulating furnace controlled by a Nest thermostat(no AC)...
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1answer
68 views

Help with a Nest E install on a old HVAC system

Hello I am trying to replace this thermostat with a Nest E but this has proven more complicated than I thought: I plugged all the cables to the nest adapter and figured that the blue wire which wasn'...
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0answers
30 views

Hookup Nest Themostat & Heatlink

I'm in the UK and trying to install a Nest Thermostat & Heatlink at home to control my hot-water and central heating and I'm having a few issues working out how my existing setup works so I can ...
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88 views

HVAC: Nest - Yet another 'C' wire question

I have a dual transformer system. At the AC/Blower unit, there are 'R_c', 'Y' and 'G' wires; there's 0VAC between the 'Y' and 'G' wires, and each shows 27VAC to the 'R_c' wire. At the boiler, there ...
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67 views

Nest Thermostat E wiring with a C-wire adapter

I wanted to get a Nest Thermostat E, but my current thermostat doesn't have a C wire. From what I read online, it's better to use a C wire, so I was considering adding a Venstar Acc0410 adapter. ...
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106 views

nest e74 code but its just heat no air

i installed the nest thermostat as instruction say i get the e74 code i checked fuse.turned power off an on now what is happening is when i attach the thermostat tothe base my relays flash quickly ...
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1answer
49 views

Secondary C Terminal on Furnace Circuit Board?

I was trying to install an Ecobee thermostat, and there was no C wire installed. When I went to install the power extender kit, I saw the standard C wire terminal was broken out of the black plastic ...
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1answer
2k views

Nest Hello Has Power but Doesn't (Often) Ring Indoor Chime?

I recently installed a Nest Hello doorbell and have run into an issue where the interior chime almost never rings. I say almost because exactly once in all my testing did it ring on the interior. I ...
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1answer
73 views

More wires than Nest needs

I had an old thermostat with wiring as below image: I wired Air Handler Trane (Model# TWE037E13FB2) in the attic just like it was before: Here is a wiring diagram of Air Handler: However, my Nest ...
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2answers
132 views

Replace thermostat wiring from my Carrier Weathermaker 8000 to my Nest thermostat

I'd like to replace the wiring from my Carrier Weathermaker 8000 to my thermostat to add a C wire. I assume I need to turn off the Carrier first, but there is no power switch that I can see on the ...
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1answer
51 views

Loud noise from outdoor unit several seconds after AC turns off

I haven't been able to find anyone online with quite this issue... I have a Carrier heat pump system, and through the winter it would often make that torpedo noise when heating the house (I later ...
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1answer
62 views

Is the PY4G HVAC unit compatible with Nest Thermostat?

I recently bought a Nest Thermostat and I've had nothing but trouble with it. The main symptom is the fan and the AC compressor won't run at the same time. Power only comes through the green wire, not ...
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1answer
57 views

Custom HVAC control

I currently have a Nest controlling my LP furnace. I'm getting an evaporative cooler installed and I'd like to also control it with my Nest. This post gave me a good starting point, but I'd like to ...
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2answers
270 views

Can I pull a common wire off an evaporative cooler transformer relay?

I have a Nest thermostat currently controlling a LP furnace. The old thermostat didn't have a common wire connected, but there was a an extra wire in the bundle and a common terminal on the furnace ...
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1answer
112 views

Try to rewire Nest and Furnace but Y is not used on Furnace

I installed a Nest at home and it worked OK. Recently, I noticed there was a power issue. Google and others suggested adding a power supply by using the existing G wire because there are only 4 wires. ...
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1answer
154 views

Another “How do I add ”c" wire to boiler for Nest

I have tried searching this forum and others, but I could not find anyone with a situation like mine. I thought it better to ask here, rather than damage something. I have a Lennox wall mounted ...
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1answer
1k views

Nest Protect Expiration Date

I just bought a set of Nest Protects and after opening the first one I noticed that its manufacture date was almost a year ago and that the expiration date was 10 years from the manufacture date, not ...
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2answers
576 views

Can the wire from the y terminal on thermostat be connected to the c terminal on heater board as pictures show?

My nest was installed with no c wire and it lost power. At this point the tech looked at the wiring diagram in a/c unit outside but I do not know what he did. A/c worked but later nest had no power. I ...
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93 views

Installed NEST thermostat heat works fine, AC compressor comes on but no fan on AC unit

I installed a new NEST thermostat last fall so only used it for heat so far. When I went to turn on AC, compressor came on but AC unit fan didn't. AC worked fine last year. Could this be a NEST ...
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1answer
98 views

Where to install C wire?

I need to run new thermostat wire since I don't have a C wire to power my smart thermostat, but need some guidance on where to hook it up. I have five wires at my thermostat, two going back to my ...
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1answer
3k views

Weathertron Xl1200 to Nest Thermostat

We have a Trane Weathertron Xl1200 heating pump with the thermostat pictured below and are trying to replace it with our new Nest thermostat. Our old system has a variable speed air handler and we ...
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1answer
669 views

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
594 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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4answers
17k 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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1answer
6k 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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1answer
429 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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1answer
191 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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0answers
638 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 ...