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Daniel Plourde
Daniel Plourde, HVAC Technician
Category: HVAC
Satisfied Customers: 251
Experience:  hvac technichian at performance plumbing and heating
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Can I connect both my old oil burner heating system (two

Customer Question

Can I connect both my old oil burner heating system (two wires, red + white) with my newer American Standard air conditioning system on a single Nest Thermostat?
Submitted: 3 months ago.
Category: HVAC
Expert:  Daniel Plourde replied 3 months ago.

hi i am dan i can help you with this. it shouldnt be a problem is it a boiler you have or a warm air furnace? was there an existing central A/C before?

Customer: replied 3 months ago.
It is an oil burner, forced hot water. The Central air is brand new, it is just on our second floor and the handler is in the attic
Expert:  Daniel Plourde replied 3 months ago.

ok it is very easy to do on the nest. the red wire from the boiler will connect to R on the nest and the white wire will connect to W then the red wire from the A/C will connect to RC on the nest and all the other wires follow the same wiring.

Customer: replied 3 months ago.
lastly I need a c-wire from the air conditioning unit. This is the manual, but I can't figure out what wire is Chttp://trane.americanstandardca.com/pdf/sistemas_ductos/MANEJADORAS/TAM7/MANUAL_DE_INSTALACION.pdf
Expert:  Daniel Plourde replied 3 months ago.

ok is the outdoor unit a heatpump or just A/C

Expert:  Daniel Plourde replied 3 months ago.

sorry i forgot to mention the B wire from your old tstat will go to C on the nest. trane uses B as the common wire.

Customer: replied 3 months ago.
the AC is in the attic, the boiler is in the basement
Customer: replied 3 months ago.
all I need to add is a wire to the c on nest and B on the air handler?
Expert:  Daniel Plourde replied 3 months ago.

acording to your picture B was already conected to the old thermostat. that is the C wire

Customer: replied 3 months ago.
Oh weird, why would they install the blue wire to C for a battery powered thermostat?
Customer: replied 3 months ago.
the blue wire goes into the Nest terminal for C-wire?
Expert:  Daniel Plourde replied 3 months ago.

even though the thermostat has batteries some of them are still powered by the system. the batteries are a backup for when the unit loses power the tstat is still powered so you dont loose programming. the blue wire will conect to C the green to G and yellow to Y. if you have any more questions about this or if this answers all your questions please let me know and if you could rate me on my service by selecting one of the 5 stars at the top of your page i would appreciate it.

Expert:  Daniel Plourde replied 3 months ago.

did you have any more questions about this?