Nest wiring issues W1/W2

[Zaazola]

I recently installed a Nest Thermostat (Not Learning) Furnace: Armstrong Air G2095AU060V14B-1

Furnace, thermostat terminals: “W1”, Wh, “W2” Orng, “Y” Yellow, “R” Red, “G”, Green, “B” Blue

Nest terminals Left (top to bottom) Y/Y, C/Blue, W, White; Right (top to bottom) G/G, R/R, *OB/Orange

Nest screen (Unconfigured Wires, Y-C-W-G-R-*OB (The “C” is “YELLOW”) the rest “Y,W,G,R, *OB” are blue.

I installed thermostat (T/S) and it seemed to work fine even though we were gone for a month after install. (Note: I did get a error “not compatible” on first install; however, I went through the compatibility check list Nest provides before ordering from “Home Depot”). I checked it from my phone daily and all was working. When I returned home I installed a new router at my home and read that I needed to do a “RESET” in order to assign a new router. When I went through the “ADD DEVICE” I experienced the same wiring not “compatible” so I just continued on like the first time.

I thought everything was fine until later in the day, I noticed water on the basement floor from the A/C lines sweating (Note: winter in Wisconsin and 20 Deg. F) Turned off the breaker and am monitoring A/C.

When the furnace is in normal mode and calls for heat… the furnace blower starts but isn’t preceded by the exhaust vent blower. The flame (DOES NOT IGNITE)

Some power reading information:

-Home heat satisfied  @ 68 Deg. T/S set down to 65 Deg. (Red wire 26 VAC) Correct?

-Calling for heat… no exhaust, no flame, no burner, 26 VAC on wires  terminals “Y”, “R”, and “G”

-(“Y” should not have power? A/C?)

-Nest T/S set to fan only… (fan @ slow speed) Power on “G” only

-When I set the Nest T/S to Emergency Heat…seems to cycle properly, exhaust runs /flame on/blower starts. 26 VAC on terminals “W”, “R”, “G” (Correct?) Furnace runs until satisfied and turns off.

Note: I do have a 1500 sq. ft (one level with Wirsbo basement heat, SET @ 70 Deg.) home in Wisconsin and “W1” and W2” says the furnace is two stage. I’m not sure if it ever runs in the second stage.

[CoolingWizard]

Technically your Gas Furnace is a model G2D095AU060V14, which is a 2-stage gas furnace. Those furnaces control boards typically do not have B terminal.  that model normally has only R, W1, W2, Y, G, and C terminals.  
When measuring HVAC control voltage, you check R to ground or to the C terminal.

Please post the picture of your old thermostat base with the wires attached.   You did not describe the outdoor unit of the AC however, you placed the W2 Orange wire in the O/B of the Nest which would indicate you have a Heat Pump.  If you indeed have a Heat Pump, the Nest Tstat will choose the Heat Pump for primary heating and the gas furnace will be the auxiliary heating.  Or, you must set the Nest Thermostat System Equipment as Dual Fuel heating system. 

The AC Cooling Wizard

[Zaazola]

Thank you....I just eliminated  the second stage W2, and that all I need with my 1500 sq. ft. house with wirsbo in the basement. The HVAC contractor just oversold me a furnace for my house when we built. When I ordered the Nest and I put the thermostat control info in (compatability)  it said that Nest "SHOULD" work with my system. Anyway, I figured it out.... Thanks

No "C" terminal but the "B" terminal satisfied the "C" on the nest.

[Jenelyn_O]

Hi there,

Chiming in — I'm glad to hear that your issue is already fixed and thanks for being a step ahead of us. Thank you @CoolingWizard, for assisting @Zaazola.  I'm going to lock this thread in 24 hours. If you have any other concerns or questions, please feel free to create a new thread.

Best,

Jenelyn