05-12-14, 03:07 PM | #21 |
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Blue Bomber, did U read post #9?
A/C 8,800' altitude. Many differences vs. England. Does this change the question? Closer to the Alaska climate than to England, but not as severe & with better solar. 8" snow yesterday. Last edited by buffalobillpatrick; 05-12-14 at 03:11 PM.. |
05-12-14, 05:44 PM | #22 |
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That's the two things I don't miss most about Colorado: the snows in May and the thin air. I can run a few miles here and still have energy for the rest of the day. I still get heckled for carrying a coat with me year-round, though. I don't know if I'll ever shake that habit.
Last edited by jeff5may; 05-14-14 at 03:57 AM.. |
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05-12-14, 07:03 PM | #23 | |
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It might be in your interest to do so before you build. BTW, did you ever post your building drawings on the forum? Somehow, I must have missed that part. -AC
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05-13-14, 03:06 AM | #24 | |
Less usage=Cheaper bills
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"Lastly, he lives in the Vancouver Canada area and the HDD are not as high as they are in a place like Minneapolis, MN." Values are in SI (C, not F). Minneapolis, MN http://cms.ashrae.biz/weatherdata/STATIONS/726580_s.pdf Vancouver, BC http://cms.ashrae.biz/weatherdata/STATIONS/718920_s.pdf You weren't kidding, Vancouver seems nice. |
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05-13-14, 10:39 AM | #25 |
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What I wanted was discussion on solar recharge of shallow loop field.
Then I asked about insulation over loop field. I expect to have excess solar heated water most of the weeks per year. 360ft2 panels mounted close to vertical. For $800 I could buy a 2nd 1000 gallon fiberglass tank. House is 48' x 36' rectangle ICF, main level is a walkout basement. About 40% of walls will be below grade. Simple 2 plane roof, ridge running East & West. Front faces East, high ceiling greatroom/kitchen, 2 bedrooms with 2 bathrooms in rear 1/2 (West end) Rear 1/2 will have upstairs 3rd bedroom & bathroom. R23 walls R51 vented steel roof. Last edited by buffalobillpatrick; 05-13-14 at 10:47 AM.. |
05-14-14, 01:34 AM | #26 | |
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That is at the core of 'low temperature heating'. With fossil fuel, the difference in lowering feed temperatures a degree or two is pretty small. With a heat pump, lowering the feed temp a few degrees makes a big change in efficiency. With solar, it means that you can heat directly with solar heated water down to a lower temperature before you need to either extract more heat with a heat pump or else rely on a back-up heat source. -AC
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05-29-14, 09:27 AM | #27 |
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http://www.byfy.lth.se/fileadmin/byf...-1018EKweb.pdf
Solar + heat pump Combisystem, Sweden study. System 5 pg82 gave best performance. |
05-29-14, 07:06 PM | #28 | |
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At a certain point, the gas boiler would do a better job than the heat pump at providing hot water. Especially when the hot water tap is running, the heat pump may just not keep up with demand. It is better doing the recovery of the hot water tank after the demand has stopped. In any case, the heat pump would just rob more solar energy from the solar heat store, where the boiler would not. Last edited by jeff5may; 05-29-14 at 07:09 PM.. |
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05-29-14, 10:04 PM | #29 |
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The heat pump, being a pretty big unit at 2 tons or so, will have no problems keeping up with DHW demand. (My little 1/2 ton unit easily keeps up with demand running only 3-4 hours per day on average.) So the only remaining reasons to switch to the boiler are if the heat pump breaks down, if the heat pump can't keep up with home heating demand (at which point you switch into hybrid mode if it's still above the balance point), if the incoming water gets too close to the freezing point, or if it becomes more efficient to use the boiler.
The only demand for 130F water (dishwasher) only needs a few gallons per use. As such, just warming up the boiler will significantly cut into the efficiency. The heat pump condenser has much less thermal mass (especially for a plate exchanger) so the heat pump will still be more efficient than using the heater built into the dishwasher. (Of course, it would help a lot to have the dishwasher as close to the heat pump as possible. Like put the heat pump in the basement directly below the kitchen.)
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05-30-14, 04:06 AM | #30 |
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The topic was what happens when I fill up my hot tub.
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