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hgoed
Registered Users
Posts:5
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| 10/03/2008 10:19 PM |
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I have just bought a plot in central MN
with a beautiful southern exposure. As it gets pretty cold here in
the winter, I would like to solicit some thoughts on how to best go
about implementing efficient heat. For background—I'm still in the
planning stage for a build next year and the home is about 2100ft2
with a full basement (R32walls and R 40 roof). Although I am not a
rich man, not making things worse is a “fiscal priority.” As my
big extravegance, I would like to install an Endless Pool (~2700gal
of 80degree water—flame me if this is stupid, but I've already had
two back surgeries and I need some help). Anyway, it seems that full
solar will be cost prohibitive (my best guess is about $60k, so I
might be able to approch that in 5 years), so—thoughts on whether I
should start with solar hot water, an electric boiler and add PV over
time, build a larger water storage up front (what kind of backup
heat), or any other ideas [?micro-cogenerators, wood/pellet boilers, or something else I haven't thought about]. Thanks for
any replies.
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senecarr
Registered Users
Posts:160
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| 10/05/2008 11:41 AM |
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Are you looking at heating the whole house, or just the pool?
I would say your best bet would be to install a geothermal system for starters. If built into the mortgage to build the house, it will "pay for itself" because your mortgage plus heating / cooling bill will be less than a traditional system operating cost plus mortgage.
It also has the benefit that it would make powering with wind or solar possible. There's no way to use electric power to operate a gas or oil based heater, that's for sure.
Also, as the home isn't built, take a look into building it with SIP's and ICF's. You'll get high R values and low infiltration. Also look at if a designer can build the house to try to take advantage of passive solar. |
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hgoed
Registered Users
Posts:5
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| 10/05/2008 12:51 PM |
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Thanks for the reply.
The house will likely be SIP for the walls and roof, and I'm still deciding on the foundation. I have looked into geothermal, and that's actually what prompted my post. Geothermal is great, but it is a pretty big up front cost and still uses quite a bit of electricity, which I'd eventually want to supply with a PV system (grid tied). While it still seems the most likely option, I was wondering if it were even possible to heat the whole house with solar hot water, since I'd have to have a larger system to heat the pool anyway. I'm kind of suspicious that the hot water system would have to be too large to be practical, but I don't know.
As far as passive solar, I'm designing more of a solar tempered home. From my crude calculations, it's actually more expensive in cold climates to put in large triple pane windows, massive storage and insulated shades/shutters than it is to go the active route. By many reports that I've read, it's also less comfortable. Any thoughts would be appreciated, though.
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Brock
Registered Users
Posts:209
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| 10/05/2008 7:30 PM |
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| Go for the geothermal, water to water for you small pool. It is a higher up front cost but if it’s built in you’re your home loan that is the cheapest way to get it. We have an indoor 16k gallon pool with a 1k gallon hot tub. They are heated with geo and we love it. I wouldn't consider an electric boiler, since the geo can be 4 times more efficient as straight electric, at the worst, geo hits 100% efficient. You also should get a de-super heater so you conventional hot water heater won't run much. I also have 1kw of solar PV up on the roof, everything else in my PV system is designed for 6w of panels, and hopefully I will keep adding them as time goes on. |
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Green Bay, WI. - geothermal heated indoor pool with a small solar setup |
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hgoed
Registered Users
Posts:5
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| 10/05/2008 8:33 PM |
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Thanks. Geo does seem to fit for most of the needs-- it will allow me to use forced air in rooms (bedrooms) where I would prefer carpet, and in my impression hydronic radiant cooling would not be worth the effort. I'm a bit wary about using a desuperheater for the water, since for 3-4 months a year I won't need either heating or cooling. That's where I thought the solar would be most useful. Brock, how did you fill those gaps, or do you run your system all year?
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Brock
Registered Users
Posts:209
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| 10/06/2008 11:19 AM |
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It is true that in the spring and fall it doesn't run as much. But if your keeping an endless pool warm you will run a given amount of time just to maintain it. As long as you have a separate de-superheater tank in front of you main one you will be fine.
Yes you could add solar hot water as well to that pre tank as well, but I think that money is better spent of a geo system. If you can do both great, but if not I would choose geo for sure and if you had any extra money left over grow your solar PV system. Our geo does 90% of our domestic hot water (10% done with the traditional NG hot water heater) even in the slow times like now, in summer we had too much hot water and we haven't gone through a full winter yet.
I would like to add solar hot water, but to fill in the gaps that are left from the geo it just doesn’t make since. In summer we heat the indoor pool and domestic hot water and cool the house in one step, avoiding the field all together. |
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Green Bay, WI. - geothermal heated indoor pool with a small solar setup |
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