Heat pump efficiency

Old 02-16-15, 02:58 AM
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Heat pump efficiency

I am experiencing single digit temps for lows. I have an old heat pump (R22) for my downstairs heat with a propane furnace backup. The upstairs is a newer heat pump (R422) with electric aux backup.

My downstairs furnace is running about 50% of the time with the heat pump running full time the furnace is off. I think I'm a little low on R22 charge because it did not seem to do this other years.

My upstairs heat occasionally runs the AUX heat with these low temps.

Just wondering if I should switch to emergency heat downstairs to save some on heating cost by not running the heat pump. Propane cost about $3 a gal here.

Another question. My R422 unit seems to go into defrost mode much more often than my R22 unit. Is that typical?
Old 02-17-15, 07:44 AM
Join Date: Dec 2012
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propane at $3/gal is roughly equivalent to electricity at 12 cents/kw-hr .
I'm guessing that MD electricity is closer to 15 cents/kw-hr - so unless your heat pump is just not working properly, or is covered with snow, or is defrosting excessively, the heat pump should be cheaper to operate until propane hits $5/gal or more..

Comfort is a separate issue - sometimes it's just more comfortable running on AUX and paying the price.

The defrost frequency will depend on what the manufacturer and or installer thought was a good way to operate, so it's not a surprise that they behave differently.

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