Heat pump wiring help


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Old 12-04-20, 05:22 PM
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Heat pump wiring help

My parents have a Nordyne 3 ton heatpump package unit and indoor electric furnace/heater There is only 5 wires for the thermostat. Red,yellow,white,green,blue. The heatpump outside has a 24v transformer I believe its feeding the heatpump relay board. The inside electric heater also has a 24v transformer. A friend of theirs installed a new digital thermostat and now the ac unit is not working. Only the inside electric heater works. I know they have a standard thermostat not one for a heat pump. He left the jumper in the R Rc. They are not getting 24v from the outdoor transformer. Im going to have them replace the transformer. Do they need a thermostat with a RC and RH and then put each hot wire from the transformer on RC and RH? Im in So cal and my parents live in Jacksonville fl. Any help would be appreciated. Thanks!
 
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Old 12-04-20, 08:14 PM
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Welcome to the forums.

You didn't leave us much technical info. If you only have 5 wires at the stat...... doubtful there is a second transformer or if there is....... it's not part of the stat wiring equation. The transformer that runs the system is the one in the air handler.

Five wires minimum to run a heat pump system. This is what I needed to know.
My guess........
red ------------> R/Rc (24v)
yellow -------> Y (cooling)
white ---------> W (heating)
green --------> G (blower)
blue ----------> O/B (heat/cool reversing valve control)

No C at this location. Someone was probably trying to install a smart stat.
Good chance a fuse was blown in the air handler.
 
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Old 12-04-20, 10:31 PM
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PJ thanks for the reply. The outdoor unit is model # P7RD-036K. Indoor electric heating furnace is a Coleman Evcon Presidential model# 3500A812. So their unit is not a heat pump my apologies its just a single stage package unit. There is 3 wires inside the outdoor unit that go to the thermostat Red 24v from outdoor transformer, green fan, yellow compressor. The only wires that connect into the furnace is going to the thermostat and thats a red 24v and white for heatstrips. Since i have 2 transformers Can i connect the furnace 24v to R and the outdoor 24v to the RC? of course ill remove the jumper.
 
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Old 12-05-20, 08:44 PM
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I'm fairly confused. You have a packaged unit. That is typically heating and A/C. It has a blower in it.

If the blower is in this unit why is there an electric furnace ?
How does that work ?

Rc -----> Red 24v from outdoor transformer,
G -------> green fan,
Y ------->yellow compressor.

Rh -----> red 24v from electric furnace
W ------> white from electric furnace.

Remove R jumper.

 
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Old 12-06-20, 09:38 AM
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Thanks. I was confused myself. There is a PSC blower inside the outdoor unit. There is no defrost board only A relay board. I believe the unit they have is a standard AC unit. but can be converted to a heat pump. I was under the impression they had a heat pump and their electric furnace was their emergency heat. This is for a mobile home, so wonder if it changes things. Thanks for the wiring confirmation thats the only way it makes sense to wire it with 2 transformers. Their thermostat doesnt have a Rh .only R and Rc. If i remove the jumper could i use R for heat transformer and Rc for cool transformer?
 
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Old 12-06-20, 09:45 AM
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Yes..... R = Rh.

Typically package units don't share ductwork with anything else.
You either have two sets of ductwork or somehow one blows thru the other one.
 
 

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