Hvac / thermostat question

[Redrig]

Hey all ,

I was wondering if there are any hvac folks that can help me out.

I had a new system installed just in April. At that time I just had a standard Honeywell non smart type of thermostat. ( current thermostat uses batteries )

I just got a Google nest "smart" thermostat and was looking at the instructions and how to install am a little confused.

Here is the pic of the furnace board .



My question is mainly ... by looking at this pic , is it possible to tell oif my common wire is currently powered ? The Google nest needs a common wire that is powered.

The system is an amana nat gas furnace and outside ac unit if that matters . I'm just confused by the wiring and don't want to mess anything up.

Here is how the Honeywell is currently hooked up. But again, this one runs off batteries .



Everything works great .

Thanks for any help on the powered wire and wiring question .

 

[Redrig]

And I guess the second question would be.

I have a multimeter, how could I confirm if it is indeed powered ?

 

[dingbat]

And I guess the second question would be.

I have a multimeter, how could I confirm if it is indeed powered ?

If it was powered you wouldn’t need batteries.

 

[Redrig]

Current honeywell thermostat was installed on previous system though , and in that configuration it had to have batteries. Common wire didn't have power.....

 

[bruceb58]

You need another wire connected to the C on your HVAC board.

 

[tpenfield]

Yup . . . the 'C' wire. . . I went through 2 Nest units until I got that sorted out on my home system (heat only). Supposedly the Nest units will work without the C wire connected, but my results proved otherwise.

I went with Ecobee and put in a 'C' wire adapter.

Not sure why you have your wiring spread across 2 wires, but not really my wheelhouse.

 

[Redrig]

You need another wire connected to the C on your HVAC board.

Okay, that makes sense . I will run another thermostat wire , this time a 6 wire .

Bruce, when I do that. Is it simply a matter of adding the extra wire to the "C" on the board . (Does it matter that there is already a wire on it ? I believe for the AC relay)

Thanks again .

 

[Redrig]

Yup . . . the 'C' wire. . . I went through 2 Nest units until I got that sorted out on my home system (heat only). Supposedly the Nest units will work without the C wire connected, but my results proved otherwise.

I went

Not sure why you have your wiring spread across 2 wires, but not really my wheelhouse.

Yup . . . the 'C' wire. . . I went through 2 Nest units until I got that sorted out on my home system (heat only). Supposedly the Nest units will work without the C wire connected, but my results proved otherwise.

I went with Ecobee and put in a 'C' wire adapter.

Not sure why you have your wiring spread across 2 wires, but not really my wheelhouse.

Good info on the smart thermostats . Did you like the Nest while you had it ?

And I think I have the 2 wires for this.

One group to the thermostat.
Smaller group outside to the ac unit.

But not really my wheelhouse either . I just want a smart thermostat , this current Honeywell is allegedly a decent model but the Temp accuracy i really question at times.

 

[dwco5051]

Here is the Honeywell wiring for your original base;

Rc 24VAC power from cooling transformer
R 24VAC power from heating transformer
W Heat relay (stage 1)
W2 Heat relay (stage 2)
Y Compressor contactor (stage 1)
Y2 Compressor contactor (stage 2)
G Fan relay

C 24VAC common. For 2 transformer systems, use common wire form cooling transformer. (optional if batteries are installed)

 

[bruceb58]

Okay, that makes sense . I will run another thermostat wire , this time a 6 wire .

Bruce, when I do that. Is it simply a matter of adding the extra wire to the "C" on the board . (Does it matter that there is already a wire on it ? I believe for the AC relay)

Thanks again .

Yep...just add to that terminal

 

[Redrig]

Outstanding. Running a new wire now as that all makes better sense now.

And I am glad I asked this , looking at current setup. My second heat stage is not hooked up , and it's a 2 stage furnace . So there are a couple bonuses of running a new wire

Thanks everyone

 

[Redrig]

Okay , I think I got this knocked out . Ran a new 18/8 wire. Now the wiring is more "standard"

Nest is installed and tests appear to be good. Thanks again

 

[bruceb58]

Does your Nest support 2 stages of heating and 2 stages of cooling?

 

[Redrig]

It does yes. There is a setup part at the beginning and you test each mode/wire.

 

[Redrig]

 

[bruceb58]

Awesome...I installed a Nest for someone years ago and it didn't have that feature.

I installed another Nest for a friend last year but he doesn't have 2 stages. They have done a really good job with their setup.

 

[Bob_VT]

I put a smart Honeywell in a few years ago and had to run the transformer and C wire because there was no C on the furnace. Merry Christmas STAY WARM!!

 

[mike_i]

This isn't in my wheelhouse either but aren't the batteries just to power the clock and display?

If it was powered you wouldn’t need batteries.