Thread: My new project
View Single Post
Old 04-21-13, 06:25 AM   #91
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.

mrd is offline   Reply With Quote