4 ms·
And even the low-temperature-capable heat pumps reduce toward 100% at the low temperature end, IIRC.
by a9h74j 4y ago
And even the low-temperature-capable heat pumps reduce toward 100% at the low temperature end, IIRC.
- mikeyouse 4y agoYep, here's a spec sheet for a unit I'm looking at as a drop-in ducted replacement for my existing system -- it has all of the models listed, but I'm looking at the 4-ton unit (12k btu per ton, so 4-ton = 48k BTU, hence the MDU18048): https://mrcool.com/wp-content/dox_repo/mc-uni-perf-ss-en-01.pdf https://mrcool.com/wp-content/dox_repo/mc-uni-perf-ss-en-01.... It takes 7kw at 17ºF to provide 48k BTU. There are 0.293W/hr per BTU so 7,000W = 25k BTU "in" and 48k BTU "out" or a COP of 1.9. At -15ºF, it's using 5.9KW but can only produce 28,500. So a COP of ~1.4. Still better than electric resistive heating but not by much. At 40ºF, the COP is more like 3.3 which is in line with the very efficient numbers. Fortunately my 99% design temp is ~8ºF and my area only sees 20hrs below zero per year, so this will work just fine for me.