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dutchslab
question about common and y/y2 wire on furnace and thermostat
dutchslab

Hi all!  I am installing an ecobee3 lite thermostat to replace my vanilla thermostat.  I noticed the common wire going to my thermostat was not energized, so I traced it down to my furnace's electrical board.

I noticed there are two thermostat wire bundles running to my furnace (see attached photo):

1. The first bundle of wires I can trace back to my thermostat.  They are connected to the Y/Y2, W, R, and G ports on the furnace.  The Blue 'C' wire has been intentionally snipped and is not connected to C on the furnace (which is what I want.)

2. The second bundle of wires is connected only to the Y/Y2 on my furnace, and the C wire.  I tried to trace where these are going, and I am not sure.  One potential place is to my AC unit bolted outside my house, but I've yet to confirm that.

I am wondering a few things here:

1. Where is that second pair going to?  Pretty high chance its going to my AC unit?  If so what are those wires specifically used for?

2. Whether or not its going to my AC unit, is it safe to share that C wire with the bundle that goes to my ecobee thermostat?  Since that blue wire was apparently intentionally cut off, I'm afraid to run it in parallel for fear of burning something out on the furnace (unless consensus is that I shouldn't be.)

Thanks for your advice! 

Attachment: 
Jack
Re: question about common and y/y2 wire on furnace and...
Jack

Quick answer "C" is the 24 vac common, "R" is the 24vac hot, "W" is the call for heat, "G" is for fan (used when termostat fan switch is in "ON" rather than "Auto") , And the "Y"'s are call for cooling.

So yes the second set is  to the outside unit of your AC and yes you can the Blue wire to the "C" terminal along with the AC wire.

Jack

 

Jack

dutchslab
Re: question about common and y/y2 wire on furnace and...
dutchslab

That did it, ty Jack!

Darryl
Re: question about common and y/y2 wire on furnace and...
Darryl

Hello, this is Darryl and I'm new here, i want to buy furnace model number dgaa070bdta, can anyoone please share its proper details ?

Jack
Re: question about common and y/y2 wire on furnace and...
Jack

Darryl, not sure what info you want. It is a small 56BTU output Coleman furnace, probaly used in mobel homes. It is an 80% effienct unit. Will have to be oreder for NG or propane, or if NG unit is oreder and is going to be used on propane a conversion kit will need to be ordered. You can download a users amnual here https://www.searspartsdirect.com/partsdirect/user-manuals/dgaa070bdta-co...

Jack

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