New system , need help with wiring a tstat


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Old 07-20-15, 12:37 PM
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New system , need help with wiring a tstat

I am having some trouble getting my thermostat wired correctly. I replaced an old unit with the following;

outside unit Rheem RP1430AJ1 14 seer 2.5 Ton

http://resource.gemaire.com/is/conte...ss.pdf?fmt=pdf

indoor air handler Rheem 3617STANJA 3 Ton

http://resource.gemaire.com/is/conte...wd.pdf?fmt=pdf

The tstat that I have has three leads. I know there is a reversing valve in the heatpump that energizes when heat is needed but I just need to wire this for cooling only with the possibility of using the heat cycle. I have a simple dial type tstat with three leads in use. Any help on how to wire this would be really helpfull. Do I need a more advanced tstat?
 
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Old 07-20-15, 01:28 PM
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Usually four wires are required for heat pump operation.
R - 24vac
Y - compressor
G - inside blower
B - reversing valve. 24v to B for heat and 0v to B for A/C.

What thermostat are you using? It may not run a heat pump in heat mode.

You could use just three wires and combine the Y and G at the air handler.
With only three wires you can't have aux. heat but in your location.... a heat pump itself cannot supply enough heat ?
 
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Old 07-20-15, 01:42 PM
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It definitely will not produce enough heat in the winter months but perhaps in the fall and spring. I just want cooling to work. I have three leads right now so should I replace it with a tstat wire with more?
 
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Old 07-20-15, 01:46 PM
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If you just want cooling to work for now.... use the following wiring.

R - 24vac
Y - compressor
G - inside blower

In the future you will need a stat that can operate a heat pump and preferably have at least four wires between the stat and the air handler. If you have electric reheat coils in your air handler then you'll need at least five wires from stat to air handler.

You will also have several wires between the air handler and the compressor unit to run the defrost board.

I'm a little lost here.... you had this equipment installed and it wasn't wired by the installer ?
 
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Old 07-20-15, 01:57 PM
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I roughed the system in and the installer came by this weekend to braze evac and ready the lines. He wired the system but said that the wiring diagram confused him because it is a heatpump. Something about the reversing valve on a rheem is different then all other manufacturers. It energizes for heat mode not cool mode. Im trying to tackle this myself because everything is ready minus a few oz of refrigerant due to lon lineset (25 ft).
 
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Old 07-20-15, 02:03 PM
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Ok... so wire that thermostat in temporarily and then you'll need to add the additions I've mentioned.

Tell the guy not to be scared by the B wire. In your system..... B gets energized for heat. A heat pump type thermostat can operate that way just fine.
 
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Old 07-21-15, 07:18 AM
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Thanks for your help Pete.
 
 

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