Rheem heat pump and 3m thermostat


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Old 07-13-14, 12:41 PM
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Rheem heat pump and 3m thermostat

I installed two rheem two ton heat pumps a couple years apart a few years back. They work great except when it gets in the single digits. Both units have 7kw heat strips which should put out about 25k btu each which is way above the heat loss for this house if both heat pumps are still putting out around 9k btu at 10 deg and then the strips are putting out another 25k. I would be looking at equivilent close to 5 ton total heating capacity for the house. I have just been using a couple of space heaters on those days and they make up the gap nicely.

I looked at the manual today and saw something about jumpering E and W2 for heat strip operation. I currently have my 3m radio stats setup as W instead of E but it is the same thing. Cool mode has always worked great on both. I have the thermostat already setup for electric heat and heat pump. Since this is not Rheem thermostat I want a second opinion before jumping W and W2. It seems like that could be the problem but again I just want a second opinion.

I know heat strip operation is more expensive BUT so is operating both heat pumps 24/7 in the winter since they can not meet their set temps. A few short minutes of strip heat should be all it needs.
 
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Old 07-13-14, 01:07 PM
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I guess that you are referring to the Rheem manual. It is unlikely that the 7 KW heat strips are staged but I will try to check.
 
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Old 07-13-14, 01:09 PM
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Do you have an air handler model number?

 
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Old 07-13-14, 02:27 PM
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The manual on the 3m and the rheem conflict. Odd. You would think the thermostat would automatically call second stage heat which would trip the heat strip. I just get the feeling that is not happening because 27kw x 2 should be more than enough to heat a 1800 sft house.

The air handler is

RHLLHM2417JA

and the outdoor units are

13PJL24A01

The heat strips are

RXBH1724A07J - 7kw (27,000 BTU)
 
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Old 07-13-14, 03:01 PM
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You do have two 3.6KW elements per air handler...
http://cdn.globalimageserver.com/fet...ication-sheets

I'd be surprised if both 3.6KW elements are not energized by your W2 signal in each unit but I see nothing to support this in this manual.

I'd use a clamp on Amp meter to determine if both elements are energized with a W2 demand.

A picture of the wire connections or your wiring diagram would be of assistance.

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