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Solar Air Heating Newbie shooting for the moon.

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  • Solar Air Heating Newbie shooting for the moon.

    Hey guys, thanks for having me on the forum.

    I recently installed a Solar Heater on my home. I looked up several designs, before deciding upon one which uses perforated aluminum soffit as an absorber, in a box glazed with a double pane sealed unit, installed upon my SW facing 7/12 pitch roof.

    I treated it as a skylight when installing on the roof, cutting penetrations for the ductwork.

    Insulated 6" flexible ducting carry the supply and return through attic space, into the living space, where a ceiling mounted diffuser is used, and baseboard level filtered return. I used solid 14x3 ducting in the stud cavity of the partition wall where the return is located.

    I feel like 31 total feet of ducting is pushing it, but hey - I figure I'd tackle the more challenging configuration first, and the future locations / designs will be easier?!

    A 104 CFM fan on a dimmer switch takes care of pushing warm air into the room near the ceiling diffuser.

    So far my results with an Anemometer suggest that I can push more air through this and it would be more efficient. I am however seeing 15 degrees above ambient in sunny conditions - even in -20 celcius outside temps.

    I have dozens of pictures of every step of my build and install, but it might be a little presumptious of me to go crazy on my first post of the forum. Also see the pic attach size is relatively small. I will use a pic hosting site if that's preferred?

    Hoping to see and learn lots here, and get better at making these. I want to install at least two more on my home, along with one on my garage.

    Thanks,

    Jason

    heater1.jpg

  • #2
    Have you been to builditsolar.com ? Lots of stuff about air cooled collectors.

    Any dampers for thermsiphoning ?

    More air will increase thermal efficiency, but may be more drafty and for that reason uncomfortable. More noise too.

    I'd flash the collector/roof interface differently, but it ain't my roof.

    The air mover's OK on a dimmer ?

    Most of this forum is about PV, but some thermal slugs hang around.

    Comment


    • #3
      Originally posted by J.P.M. View Post
      Have you been to builditsolar.com ? Lots of stuff about air cooled collectors.

      Any dampers for thermsiphoning ?

      More air will increase thermal efficiency, but may be more drafty and for that reason uncomfortable. More noise too.

      I'd flash the collector/roof interface differently, but it ain't my roof.

      The air mover's OK on a dimmer ?

      Most of this forum is about PV, but some thermal slugs hang around.

      Hey JPM, thanks for the response.

      Not sure I understand exactly how you would or could apply thermosiphoning to this system - but hey, that's why I'm here - to learn.

      I did install the perforated aluminum soffit as baffles in the box itself, but there are no restrictions in the ducting or anything - except for the diffuser in the ceiling. It has a flap that can be closed, like a typical forced air diffuser.

      The way the baffles are installed, air is forced to pass through, although I did leave a small gap underneath the glazing, didn't want the aluminum in contact with it.

      As for the flashing detail, I stripped the shingles off the roof, cut back the tar paper so that the box sat directly on the roof sheathing, holes cut where my penetrations went through. PL Premium / Lumber adhesive around the perimeter where the box sits on the sheathing.

      Then I applied ice and water shield on four sides up to within an inch of the glazing. Step flashings at the top. I reshingled everything, including using a framed cricket at the top of the box, and then installed steel cladding with drip edges on all four sides.

      I did wonder for some time what the best method would be. I considered building the unit off the roof itself, and then trying to use vent boots or something similar where the supply and returns went in. What else would you do? I know I'll switch to torch on next time around, as opposed to peel and stick Ice & Water shield.

      The fan is a simple tubeaxial ball bearing 15w 105cfm unit used in refridgeration, .16Amp, on a 15amp dimmer. Works fine, and is on a breakered circuit.

      The fans and mechanisms to automate it/them turning on and off are what interests me next.

      baffles.jpg

      Comment


      • #4
        You're welcome.

        On thermosiphoning: As/when the air in the collector is colder than the air in the conditioned space, like at night or example, the air in the collector it will become more dense (less buoyant) and want to drop in elevation. The path for that is usually the opposite way from when the sun is shining. Air from the heated space will then circulate to replace the air leaving the collector. Unless a damper/other means is used to prevent such flow, it will remove heat from the dwelling.

        Comment


        • #5
          Originally posted by J.P.M. View Post
          You're welcome.

          On thermosiphoning: As/when the air in the collector is colder than the air in the conditioned space, like at night or example, the air in the collector it will become more dense (less buoyant) and want to drop in elevation. The path for that is usually the opposite way from when the sun is shining. Air from the heated space will then circulate to replace the air leaving the collector. Unless a damper/other means is used to prevent such flow, it will remove heat from the dwelling.
          Gotcha,

          It didn't seem to be an issue this past winter (which hasn't ended yet here in Nova Scotia unfortunately).

          The curving path of the insulated ducting for supply and return might play a role in that, not sure.

          I do have the diffuser grille that can be closed, so at least it can't occur with any velocity !

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