05-02-14, 02:08 PM | #11 | |
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-AC
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05-02-14, 03:51 PM | #12 |
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Try to decide if insulation over shallow loop field is worth the cost.
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05-08-14, 12:43 PM | #13 |
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Another large Solar heated slinky loop system 5800ft2 in Alaska,
some videos & nice diagram: Ground Source Heat Pump and Solar Thermal | Cold Climate Housing Research Center |
05-11-14, 11:23 AM | #14 |
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Afaik, insulating above a shallow field would be hugely detrimental to the field as the sun is greatly responsible for reheating the ground.
Additionally, if you are considering doing a field in series, be sure to have the panels before it returns to the field. Most heat pumps have a limit on the temperature of the incoming ground loop of around 110. I am not sure why this is, but I've seen it on the specs of every heat pump I've looked at. |
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05-11-14, 02:31 PM | #15 | |
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05-11-14, 03:50 PM | #16 |
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I think it's one of those inconvenient Physics limitations, concerning the characteristics of the refrigerant.
-AC
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05-11-14, 07:08 PM | #17 |
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Once the temperature goes that high, it would make more sense to bypass the heat pump in which case it's a moot point. The real limit is how high the suction pressure can go without overloading the compressor.
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05-11-14, 08:58 PM | #18 |
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I agree. If you have access to 110+ degree water, it would use less energy to just pump it through a traditional hydronic heating setup.
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05-12-14, 10:12 AM | #19 | |
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Quote:
This is exactly the place where traditional thinking fails in low temperature heating installations like solar, geothermal, etc. Very few hydronic installations (Daox excepted) have built-in efficiency to take advantage of feed temps on the 110 range (and lower). Vlad's house works with 12" spacing & aluminum heat spreaders because he heats all the floor area, has rigorously reduced infiltration, and put in very good insulation from the start. With three floor levels, his floor area/house volume ratio is fairly high, which favors radiation. Also because his house is large and vaguely tends toward a cubic form, his external area/house volume ratio is relatively low so his house favors lower skin losses. Did I mention his floor is topped with porcelain tiles, which has a very high U-value? Lastly, he lives in the Vancouver Canada area and the HDD are not as high as they are in a place like Minneapolis, MN. Vlad reported feed temps in the 112 range when the weather got really awful. Of course, awful in Vancouver could be a relief in a Minneapolis winter, or a Colorado winter at high elevation. -AC
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05-12-14, 01:37 PM | #20 | |
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What do you see when you compare the available solar gain of the site in UK with your site located 4000 feet up in Colorado? Does that comparison make sense? -AC
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