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Phil, Mechanical Engineer
Category: HVAC
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Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
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We are having issues setting up or new Nest Thermostat. The

Customer Question

We are having issues setting up or new Nest Thermostat. The wires our system has is:
Rh, W, C, G, Y/Y2 & O/B
When we hooked it up to new thermostat it said we couldn't have an O/B wire without Y1 but there wasn't a wire in the Y1 port when we first took it apart
Submitted: 7 days ago.
Category: HVAC
Expert:  BillyHvac replied 7 days ago.

hello,

My name is Billy.

Exactly what terminals were used in the old thermostat?

Customer: replied 7 days ago.
Rh, W, C, G, Y/Y2 & O/B
Expert:  BillyHvac replied 7 days ago.

Ok so on the Nest you will use yellow to Y1

Have you tried it in Y1 yet?

Then of course orange to O

Customer: replied 7 days ago.
do we still use the Y/Y2 wire? When we tried that setup we weren't getting warm air only cold.
Customer: replied 7 days ago.
The color of the wire going into Y/Y2 is reddish brown and our yellow wire wasn't connected
Expert:  BillyHvac replied 7 days ago.

Do you have Rheem or Ruud product outside?

Expert:  BillyHvac replied 7 days ago.

ok, I say yellow because that is color code...

BUT...whatever wire you had on Y in old thermostat goes to Y1 in Nest

Customer: replied 7 days ago.
Ok, so I leave the yellow wire disconnected? I'm not sure if I have rheem or ruud
Expert:  BillyHvac replied 7 days ago.

If yellow was not attached in old thermostat, leave unattached and taped.

I ask because Rheem/Ruud use a different reverse valve O/B.

But we can tell soon.

So in old thermostat yellow was not attached and brown was in y/y2?

Customer: replied 7 days ago.
the yellow and black wires were not connected
Expert:  BillyHvac replied 7 days ago.

Ok so then you will put your brown in Y1 at Nest. Tell me if it recognizes it

Customer: replied 7 days ago.
It recognized it and this is what the display looks like:
Expert:  BillyHvac replied 7 days ago.

Yep, That is correct.

Expert:  BillyHvac replied 7 days ago.

does it heat now?

Customer: replied 7 days ago.
Cold air is blowing out
Expert:  BillyHvac replied 7 days ago.

Is the outdoor unit running?

Customer: replied 7 days ago.
No
Expert:  BillyHvac replied 7 days ago.

Thank you.

Do you know what equipment you have ?

Gas furnace with heat pump, heat pump only etc?

Customer: replied 7 days ago.
I believe we have a furnace with heat pump but I can't find it in our manual to be sure
Expert:  BillyHvac replied 7 days ago.

did you use a white wire on W/Aux?

Customer: replied 7 days ago.
Expert:  BillyHvac replied 7 days ago.

so no wire on w1?

Customer: replied 7 days ago.
No, the white wire is in W1 not in W2/aux
Expert:  BillyHvac replied 7 days ago.

move the white wire to W2/Aux

Customer: replied 7 days ago.
Switched the wires. It is blowong cold air and unit isn't running outside
Expert:  BillyHvac replied 7 days ago.

then it is important to know what equipment you have.

The thermostat works on dozens of types of systems but we have to let it know what that is.

Gas furnace, electric furnace, air handle, air handler with electric strip, heat pump, heat pump with aux, boiler, central air, etc...

Customer: replied 7 days ago.
I have the model numbers for both units but cannot find any information about what they are online
Expert:  BillyHvac replied 7 days ago.

what do you have for numbers?

Customer: replied 7 days ago.
Outdoor unit: 24ABB336A003
Indoor Unit: 24ABB336A310
Expert:  BillyHvac replied 7 days ago.

ok that is a regular ac not heat pump...the indoor unit is attached to a blower system, can you get number for that? And is this the only thermostat in the home?

Expert:  BillyHvac replied 7 days ago.

remove wire from o/b

move white back to w1

see if it picks up as a furnace with ac.

A gas furnace generally has an exhaust pipe to the outside if that helps.

Customer: replied 7 days ago.
It is a 58MCB deluxe 4 way multiplies fixed capacity condescending gas furnace
Customer: replied 7 days ago.
Switched the wires. Blowing cold air and outside unit not running
Expert:  D.E. Anderson replied 5 days ago.

Hi, do you still need assistance with this? Thanks

Customer: replied 4 days ago.
Nope, figured it out.

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