My new project

mrd · 04-21-13, 06:25 AM

mackerel, that is a cool spreadsheet. I see there is an ASHP HSPF adjustment table at the bottom. The adjusted HSPF value has quite an effect on the cost of ASHP operation relative to other forms of heat. So it's important the value is accurate!

I don't know precisely how that table was generated, but logic dictates a COP curve versus outdoor temperature must be assumed. The actual curve differs depending on equipment. I have seen curves in design manuals for a few different minisplit systems and they differ quite a bit. A system advertised for 'low ambient' is going to have a curve that falls off much slower at colder temps, thus the table values would underestimate the performance. To what degree the estimate can be off, I'm not certain.

04-21-13, 06:25 AM	#33
mrd Apprentice EcoRenovator Join Date: Feb 2010 Location: Milford, DE Posts: 106 Thanks: 5 Thanked 9 Times in 9 Posts	mackerel, that is a cool spreadsheet. I see there is an ASHP HSPF adjustment table at the bottom. The adjusted HSPF value has quite an effect on the cost of ASHP operation relative to other forms of heat. So it's important the value is accurate! I don't know precisely how that table was generated, but logic dictates a COP curve versus outdoor temperature must be assumed. The actual curve differs depending on equipment. I have seen curves in design manuals for a few different minisplit systems and they differ quite a bit. A system advertised for 'low ambient' is going to have a curve that falls off much slower at colder temps, thus the table values would underestimate the performance. To what degree the estimate can be off, I'm not certain.