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questions on new system for home DHW and maybe bonus radiant home heating in alaska

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  • questions on new system for home DHW and maybe bonus radiant home heating in alaska

    I live in the interior Alaska and have been doing research on upgrading my house to benefit from the sun. During the winters we can usually count on months at a time of -20F and some spikes of -50F for a week. I am mostly looking at gaining in the shoulder months as we get an abundance of sun in the spring and Fall and almost completely during the days of summer. I'm leaning more towards evacuated or vacuum tube systems do to the efficiency on cloudy and colder days. I do not want to have to worry about freezing or bursting pipes during the colder months. It seems like there is an abundance of people here with a wealth of knowledge here.

    What is the most reliable system on the market for colder climates?

    Is there anybody with the same climate or weather conditions like mine that have any input on how their system does during the colder months?

    Is it worth it?

  • #2
    Wow. I don't know if I'd even trust antifreeze at -20F ! Here in balmy northern calif, I get worried at +30F. So maybe my advice is worthless. I have a commercial (Rheem) rooftop water heater, glycol collector, and 20gal storage tank above it. I get no gain in cloudy weather. With short Alaska winter days, I don't know if vacuum thermal tubes will harvest enough to be worthwhile. Maybe a water loop around your indoor heater is the best you can do in those conditions, or see if any neighbors have any success with anything.
    Also, look at builditsolar.com for ideas.
    http://www.builditsolar.com/Projects.../solarshed.htm here's a water heater used in snowy, sunny Montana and has worked to -30F
    Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister

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    • #3
      Yeah we have some cold weather here I looked at the collector setup in Montana good build but not quit what I was looking at installing. I think the evacuated tubes might have a little better use here do to wind loss and shorter hours in the summer. I have antifreeze in my outdoor wood boiler and its tested to -40f it's good stuff and I've never had a problem. Even after coming home from the cabin for a week and it had been -50F for three days I have confirmed faith in the liquid.

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      • #4
        Read in this section about the problem with evacuated tubes, they are not reliable at low temps. There are many reports of the heat pipes splitting requiring repair or replacement.
        The glycol concentration required to protect down to -50 would seriously affect the heat transfer properties of the array, possibly negating any efficiency advantage gained from the use of evacuated tubes.
        A Flat plate drain back system will work well in the shoulder months with no concerns of freezing in the extreme cold month's.

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