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Old 03-09-13, 11:39 PM   #3
Join Date: Feb 2013
Location: mendocino, california
Posts: 67
Thanks: 7
Thanked 2 Times in 2 Posts

Thanks, AC_Hacker, for your response. You are correct, we don't need any where near the heat our Wisconsin friends do...but aren't you from Portland? I grew up there, and don't remember it being all that harsh! There was a heat load analysis done back when we got the building permit to build this house in '88, but I also know from keeping track of our water heater that the heat load is about 60M Btu per year, and DHW is something a lot smaller tacked on. The water heater...that's really all it is, but oil still in use. I've just begun messing around with the heat pump. We have 1000 SF of radiant floor. The tubes, arranged in 10-200' loops joined in a manifold, are 6" OC except in the bath where they are 3-4". The water temp going into the floor is steady at 110 deg. There is a heat exchanger between the water heater and the floor system that outputs water at 120-125 degrees, and a tempering valve mixes return water from the floor to cool the water entering the floor loops to 110.

I haven't found anyone on the coast or inland, say in Santa Rosa, that deals in ground source heat pumps, so this website, which I just recently found, seems like a godsend to me. After thinking a while about my first post, I've begun to plan an experiment to see how the Etech heat pump behaves. We have a 5000 gallon water storage tank for domestic use, the water coming from our well. I can use that water as an open source heat supply, and since the water came out of the ground, it's temperature will be a good measure of what pipes in the ground could supply. I can extract about 400k Btu by lowering the temp from 55 to 45 degrees. Then I can watch what happens on the production side of the heat pump, setting up a situation that will mimic what would happen if it were connected to the floor loops, that is, output water at 110-115 degrees, and return water at 80 running continuously for a couple hours. I should be able to get some idea what the heat pump can do.

I'm pretty sure we'll need something bigger than this 1-ton because on the coldest days our house requires about 200k Btu for heat, and that would require running it nearly all day. I'm working on reading your posts...that may be the best textbook I could find. mm
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