Quote:
Originally Posted by benpope
I think I am going to go for two units--both LG since they have the prettier indoor units--one a single and the other a double. I made up a model of my house with HEED and it says that I need a maximum of about 65000 BTU to heat on the coldest night and 38000 BTU to cool on the hottest day. This is a bit of an over estimate since I don't keep my house as warm/cool as most people, but it will still be a lot of heating and cooling. |
benpope,
With fossil fuel heat, the rule of thumb was to do a heat load (like you did with HEED) and multiply that by 1.5, and that would be the size (minimum) of your furnace.
With Heat Pumps, it's different because bigger compressors mean bigger friction and even if you have a unit with "Inverter Technology", which you probably do, when you are running at fractional power, which is almost always, you'll have to pay for that extra friction all the time.
So the Heat Pump rule of thumb is to calculate your load (HEED) and size your heat pump slightly smaller, realizing that you'll be using an axillary heating source in those unusual instances when your Heat Pump will need some help.
So your axillary source might be electric resistance, or oil, or gas, or wood, or in Xringer's case, a miniature Thorium reactor.
My house, by rule of thumb, should use 24,000 BTU. Just get me by while I was finishing up my GSHP project, I bought a 9,000 BTU mini-split. It's really too small to heat my house.
The strategy I have developed so far is to heat only the part of the house I am using, by opening and closing doors, as required.
Usually, where I live winters consist of temperatures hovering in the low-forties to high-thirties. Last winter, we had nearly a week where the temps plunged down to around 12 degrees and stayed there.
So I retreated to my 'core room' and was just fine. The mini-split wasn't even running full out. My heating cost during that time was $6.50 for the week.
That's a pretty small footprint.
So I say, start on the small side and try to stay there. Add another unit later if you really need it. That's the beauty of mini-splits.
Regards,
-AC_Hacker