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hikerjohnson · 08-30-13, 11:08 AM

Hi AC, time for an update on my progress;

I did get the books, and they were terrific reading! Tons of valuable information in them with respect to sizing fields and many other considerations. I took the time to scan them ( I have access to a high-speed scanner, so it wasn’t all that bad, and now I have a permanent copy.)

Now, due to a few unexpected (and expected) issues, I have had to back-burner a GSHP and go for an ASHP mini-split for the time being. I think I mentioned that my house was originally equipped with electric baseboard heat, so there is absolutely no existing infrastructure to use for heat distribution. I would be retro-fitting any system that I chose, at huge expense. Decisions would be different if I had existing hot air or water baseboard heat. That was the expected part, but wow, when I started pricing things out, well, WOW. Heating components, especially for low-temp water, are not cheap. Also, DIY-ing it takes time, which, you’ll see, is sparse at the present time.

The unexpected part was when I was told at work recently that I’d be away from home for the coldest 2 months of winter, leaving just my girlfriend to work full-time and feed a very hungry woodstove. That’s not acceptable, and neither is running the electric heaters to do full-house heating, as they can run significantly over $600 a month, which is about what a winter’s worth of firewood costs.

With that in mind, I did some more research, and found out that commercial GSHP’s (I had a long conversation with a WaterFurnace tech over the phone.) can only expect to get a COP of 3.5 to 4 in a typical installation, once you factor in pumping losses. I know this issue has been discussed here, but I thought, surely, that proper sizing would help improve that number. Nope.

The solution to the above issue, I hope, is a Mitsubishi HyperHeat 18KBtu mini split (Engineering Data HERE), which is on a truck headed toward my house right now. It’s cheap (Under 3K with all the refrigeration tools to do the job correctly) and easy to install. Furthermore, at 5F, it will still put out 10300 Btu/hr at a consumption of 0.87 kW, for a COP of 3.47. That’s pretty good! I’ll write up a thread to document my installation of that, and I have already in hand a refurbished electric meter to sub-meter the power that the mini-split will consume. I cannot easily measure the output of the heat pump, though. All I can report is on how comfortable it kept us, and what temperatures it can maintain. I know this machine will only support part of my heating demand, but it’s what we can afford right now; else I’d have bought the 9K model for the upstairs, too.

I am also actively sealing many little gaps in the house, and insulating the rim joist in the basement (4 inches of pink Dow, cut to size and foamed in with Great Stuff. It’s tedious, but neater than straight sprayed foam.

Anyway, I am veering off-topic. As far as GSHP goes for me, it is still interesting, but is deferred until spring. Then, I will be drilling (myself) a well to supply my garden irrigation needs, and when I do that, I will see how easy or hard it is to do. Based on that, I may put in either a pump and dump, or a small borehole field like yours to support, say, a ton of energy extraction, so that I can experiment, and also hopefully heat my basement, which I have not yet come up with a way to heat this winter besides running the coal stove.

08-30-13, 11:08 AM	#1539
hikerjohnson Submarine Renovator Join Date: Jul 2013 Location: Southern Maine Posts: 35 Thanks: 4 Thanked 5 Times in 5 Posts	Hi AC, time for an update on my progress; I did get the books, and they were terrific reading! Tons of valuable information in them with respect to sizing fields and many other considerations. I took the time to scan them ( I have access to a high-speed scanner, so it wasn’t all that bad, and now I have a permanent copy.) Now, due to a few unexpected (and expected) issues, I have had to back-burner a GSHP and go for an ASHP mini-split for the time being. I think I mentioned that my house was originally equipped with electric baseboard heat, so there is absolutely no existing infrastructure to use for heat distribution. I would be retro-fitting any system that I chose, at huge expense. Decisions would be different if I had existing hot air or water baseboard heat. That was the expected part, but wow, when I started pricing things out, well, WOW. Heating components, especially for low-temp water, are not cheap. Also, DIY-ing it takes time, which, you’ll see, is sparse at the present time. The unexpected part was when I was told at work recently that I’d be away from home for the coldest 2 months of winter, leaving just my girlfriend to work full-time and feed a very hungry woodstove. That’s not acceptable, and neither is running the electric heaters to do full-house heating, as they can run significantly over $600 a month, which is about what a winter’s worth of firewood costs. With that in mind, I did some more research, and found out that commercial GSHP’s (I had a long conversation with a WaterFurnace tech over the phone.) can only expect to get a COP of 3.5 to 4 in a typical installation, once you factor in pumping losses. I know this issue has been discussed here, but I thought, surely, that proper sizing would help improve that number. Nope. The solution to the above issue, I hope, is a Mitsubishi HyperHeat 18KBtu mini split (Engineering Data HERE), which is on a truck headed toward my house right now. It’s cheap (Under 3K with all the refrigeration tools to do the job correctly) and easy to install. Furthermore, at 5F, it will still put out 10300 Btu/hr at a consumption of 0.87 kW, for a COP of 3.47. That’s pretty good! I’ll write up a thread to document my installation of that, and I have already in hand a refurbished electric meter to sub-meter the power that the mini-split will consume. I cannot easily measure the output of the heat pump, though. All I can report is on how comfortable it kept us, and what temperatures it can maintain. I know this machine will only support part of my heating demand, but it’s what we can afford right now; else I’d have bought the 9K model for the upstairs, too. I am also actively sealing many little gaps in the house, and insulating the rim joist in the basement (4 inches of pink Dow, cut to size and foamed in with Great Stuff. It’s tedious, but neater than straight sprayed foam. Anyway, I am veering off-topic. As far as GSHP goes for me, it is still interesting, but is deferred until spring. Then, I will be drilling (myself) a well to supply my garden irrigation needs, and when I do that, I will see how easy or hard it is to do. Based on that, I may put in either a pump and dump, or a small borehole field like yours to support, say, a ton of energy extraction, so that I can experiment, and also hopefully heat my basement, which I have not yet come up with a way to heat this winter besides running the coal stove.