Single vs Multi Stage Heat Pumps


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Old 08-04-09, 11:40 AM
L
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Single vs Multi Stage Heat Pumps

We are replacing our old AC and electric furnace with a heat pump and an electric furnace with variable speed blower. The decision we are struggling with is single stage vs multiple stage heat pump.

Our house has two levels, and the upper level is always HOT in summer without AC. The ducting to the upper level should be bigger but we can't change it. Our winters in Eastern Washington can be very cold and long, so we are looking at the HSPF rating more than the SEER. We are trying to decide between two Rheem systems:

Single-stage Rheem RPQL-036JEZ heat pump 13.00 EER, 15.50 SEER, 10.00 HSPF
2-stage cooling/3-stage heating Rheem RPRL-036JEZ 12.75 EER, 16.50 SEER, 9.40 HSPF

We like the higher ratings of the single-stage unit, especially the 10.00 HSPF, but wonder what we'd be giving up by not getting the multiple stage unit. Do the benefits of multi-stage outweigh the lower HSPF and the additional $656?

Thank you for the help!
 
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Old 08-04-09, 03:09 PM
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More of a ground source guy, but anytime you can extend the run times it should help to even out room temperatures.
This applies to air or hydronic heat.

The multistage will be in low stage most of its life, and the should pay for itself over time.
Be sure whatever you get has an ECM motor, and then you can leave the fan on all the time with out too much of a power bill.

ECM motors will also try to move the stated amount of air, which is good but can lead to lots of air noise. The speed can be reduced if that happens.
 
 

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