Wiring configurations

[Jl727]

Hope this is correct. Black to common

 

 Above is coil above

furnace

 American Standard Furnace followed by outdoor Heat exchanger

 

 

 

 

Maybe someone can tell me if the Nest 3rd Gen Thermostat is compatable with my dual fuel system? I have a gas furnace with a outside heat exchanger/air conditioner. Also has outside sensors which I believe is the S1/S2 wires.

Anyone able to confirm my wiring configuration?

 

 

[MrVacca · Accepted solution]

Yes @Jl727 - your set up can absolutely work with a Nest 3rd Gen thermostat. 

[MrVacca · Accepted solution]

Yes @Jl727 - your set up can absolutely work with a Nest 3rd Gen thermostat. 

[CoolingWizard · Accepted solution]

Yes indeed it will work with your system. Your current setup is as follows :

R is Red Wire (Power IN)

B is Black wire (Power Common)

Y is Yellow Wire (Compressor Control)

G is green wire (Blower Fan Control)

W1 is Blue Wire (Stage 1 Heat)

W2 is White Wire (Stage 2 Heat)

S1/S1 are for outdoor temperature sensor that Nest will not need.   
What is confusing is it looks like the Black Wire is on O in the Furnace Control Board .

Can you take a picture of the outdoor unit label with the model number and the same for the gas furnace and post them here? I think you have a Heat Pump outside. 

Ken, The AC Cooling Wizard

[Jhonleanmel]

Hey folks, 

We appreciate your help here, @CoolingWizard and @MrVacca.
@Jl727, I wanted to follow up and see if you are still in need of any help. Please let me know if you are still having any concerns or questions from here, as I would be happy to take a closer look and assist you further.

Thanks,
Mel

[Jl727]

Still waiting on confirmation 

[Jl727]

Outdoor Heat Exchanger

 

 

[Jl727]

 

Coil unit above furnace

 

[Jl727]

Sorry I was struggling to post pictures but think I have figured it out. I have added our Outdoor Heat exchanger, the coil above the furnace and the furnace. We live in BC Canada and our present thermostat will have the outdoor unit heat untill -4deg Celsius. I will want the new setup to be 0 Deg Celsius as Electrical to expensive

[Jhonleanmel]

Hey Jl727, 

Awesome — glad to hear that your issue is fixed. It looks like we can consider this one complete, so I will lock the thread shortly unless I can help out with anything else. 

Best, 
Mel

[Jl727]

Still waiting on a response after I uploaded some requested pictures for heating and cooling equipment 

[CoolingWizard]

Jl727,

your unit outside is actually a heat pump. I know you called a heat exchanger but it’s technically a heat pump. It contains an outdoor coil, a reversing valve, a fan motor, and a compressor. The indoor unit is the indoor coil, blower motor and gas fired heat exchanger, As a heat pump system, the indoor coil can perform as a heating system when the heat pump is in heating mode.  There will be a an outdoor temperature point when the Heat Pump’s heating capacity begins to decrease.  And, at about -4°F the heat pump will need auxiliary heat to be active.

With a heat pump in heating mode, there will be ice building up on the outdoor coil. When the ice becomes to much the heat pump will enter defrost cycle. When in the defrost cycle the heat pump temporarily switches to cooling mode to use the heat to melt the ice on the outdoor coil. During this defrost cycle the indoor blower should off or the auxiliary heat be turned on.  
Typically the indoor coil, that is designed to work with heat pumps,  will have a W2 control. This W2 in the furnace activates the auxiliary heat configuration when in defrost cycle.  
The Nest Learning Thermostat 3rd Generation of fully compatible with  the system you have. You will have the ability to set the temperature at which you want the heat pump to turn off and the auxiliary heat, the gas furnace, to be the primary heating.  

Ken, The AC Cooling Wizard

[Jl727]

Thanks so much for a very informative reply. Would you be able to confirm my wiring as well? I know you had some concerns with the black wire.

[CoolingWizard]

Sure thing.  In one of my earlier replies I provided a listing of your wires being used and their function.  When you are ready to start your install, you will be prompted to go to a Google Nest website to input the wires being used Your task will be to input the wire color and terminal letter that color is attached to. And to add a letter tag to the wire to keep them straight.  This is very important for you since there are the two S1 and S2 wire that duplicate colors. Of course you will not need the S1 and S2 wires with the Nest Thermostat. Have you purchased your Nest Thermostat yet? If so, which model did you purchase?

Ken, The AC Cooling Wizard

[Jl727]

It is the third generation nest

[CoolingWizard]

Outstanding. When are you planing to start the upgrade?

Ken, The AC Cooling Wizard

[Jl727]

Well I could try tonight or tomorrow. We are having some reasonable cold weather right now so I am being cautious. I also have a furnace service scheduled for tomorrow but not sure if the tech will be familiar with the nest as they recommended Ecobee which I tried first and after reaching support was informed it was not compatible. As mentioned previously running on gas is the most economical right now in BC so I would give it a try if I am confident I can rely on having gas heat at a minimum and not damaging my system. Also do I need a "C" wire? 

Thanks again

[CoolingWizard]

I am pretty sure the black wire on B is your common wire.  A confirmation is possible with a Volt Ohm Meter set to AC a voltage and checking between R and B. 

[Jl727]

 Sorry for constantly asking for checks but I have wired as per your comments and used the black as common to connect to "C"

Everything seems to work although I think I need to set up for dual fuel in order for the heat pump to work. I selected gas when it walked me through the settings. Any advice you can offer on the setup for dual fuel. I did notice one video where they set up on the aux terminal. I do not have that wired

[CoolingWizard]

need to make a correction, since you have a heat pump the blue wire is actually supposed to be in the O position.  That is the heat pump reversing valve.  The best way is to reset the thermostat and restart the installation.  Choosing Heat pump, with auxiliary heating 

R is Red Wire (Power IN)

B is Black wire (Power Common)

Y is Yellow Wire (Compressor Control)

G is green wire (Blower Fan Control)

O is Blue Wire , (heat pump mode change)

W2 is White Wire (Auxiliary heat)

i’m sorry for the confusion

[EdwardT]

Hi folks,

@CoolingWizard, thanks for the help!

@Jl727, how's it going with your Nest Thermostat? Still need our help?

Thanks,

Edward

[EdwardT]

Hi Jl727,

It's me again. I wanted to check back in to see if you have other questions and concerns. Feel free to let me know if you do.

Thanks,

Edward

[EdwardT]

Hi Jl727,

I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.

Thanks,

Edward

[Jl727]

No think we are all good. Cooling wizard was the most help and we figured it out. When the HVAC service guy was out he was happy with everything and was also experienced with the nest so helped with the finishing touches.

[EdwardT]

Hi Jl727,

Thanks for the update. I'm glad to hear that it's working fine now. I will be locking this thread in 24 hours. Please feel free to create a new thread should you have some more questions or concerns in the near future and we'll be more than glad to help.

Thanks,

Edward

[Jl727]

I think the model is a T3007EF