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#218501 05/20/17 04:55 PM
Joined: Jul 2007
Posts: 1,335
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I'm having an issue with a new heat pump with an in duct coil. Using the existing furnace for fan and emergency heat.

I can't call the factory until Monday. Calling for heT I have 24V between R and C, and R and O plus I have power to the fan. I can't get the heat pump to fire. Any thoughts?


"Live Awesome!" - Kevin Carosa
Joined: Jul 2007
Posts: 1,335
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Maybe this will help. Each column is a piece of equipment in the puzzle and how they are connected. Hope this view properly at your end. Thermostat is Heatpump enable

HP=Heat pump
Furn=Furnace force air
Tstat=Thermostat

Tstat Furn HP

[R]-----------[R]--------[R] Heat
[C]-----------[C]--------[C] Common
[AUX/E]-----[W]--------[R2] Emergency heat
[OB]--------------------[O] Heat/cool valve
[G]----------[G] Fan
[Y]-----------[Y]--------[Y] Cooling


"Live Awesome!" - Kevin Carosa
Joined: Mar 2004
Posts: 947
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twh Offline
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Calling for heat, should O be energized and read 24 volts to C? That would be zero volts from O to R. I think OB is the same as W which is 1st stage heat.

Joined: Jul 2004
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Does it run in "cool"? If not, be sure the time out relay is OK. These things use a time delay relay (usually solid state) to prevent short cycling. Some times you have to wait a minute or two to see if it is going to go.,


Greg Fretwell
Joined: Jul 2007
Posts: 1,335
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Member
Crap! Your right. It's been ages since I dealt with furnace controls. Before electronic stats. The R is or was commonly called common. It should be 24v between Orange and Blue, not red.

The furnace in question still called the R, common and W for heat. It tripped me up once already. Grrrrrr!

Thanx


"Live Awesome!" - Kevin Carosa
Joined: Oct 2016
Posts: 5
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New Member
Greetings Ya'll,

It looks like this got "Cleared up" back in May 22, 2017.

I'm curious as to how it turned out, & also why a "Duct Coil" was used, instead of an "A" Coil in the Plenum.


When you Stand for The Truth, Sometimes you Stand Alone.

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