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Hot Attic = Hot Water?

Homestar Plumber
Homestar Plumber Member Posts: 3
What is the best way to use my hot attic to provide me with a hot shower? I've thought of using an indirect water heater heated ONLY with the attic heat , but I am worried about legionellae bacteria as the water will never really be that hot and certainly not for a sustained period of time.

Comments

  • Kevin_in_Denver_2
    Kevin_in_Denver_2 Member Posts: 588
    RISA= Roof Integrated Solar Absorber

    Hot attics can be water heaters, the jury is out if they are cost effective.



    Attached is a good report.
    Superinsulated Passive solar house, Buderus in floor backup heat by Mark Eatherton, 3KW grid-tied PV system, various solar thermal experiments
  • hot_rod
    hot_rod Member Posts: 14,835
    Solar Attic

    I've seen this product advertized before. No reason you couldn't build one to do DHW, and ventilate the attic.



    hr
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Kevin_in_Denver_2
    Kevin_in_Denver_2 Member Posts: 588
    Great Find, Rod

    No doubt hot attics are a problem, and this is a very simple way to cool the attic and heat some water.



    I would think that any hydronic unit heater or fan coil would work. A solar-type differential control with a tight delta T could be the controller.



    One issue is that in cold climates, most attics are vented and might freeze. The solution is drainback of course, so the device must be designed to empty completely.



    I think drainback helps solve the legionella problem as well, because you don't have the potential for long loops of stagnant water. All the water drains back to the preheat tank. From there it goes to the backup water heater, which will top off the temperature, and kill the bacteria.
    Superinsulated Passive solar house, Buderus in floor backup heat by Mark Eatherton, 3KW grid-tied PV system, various solar thermal experiments
  • hot_rod
    hot_rod Member Posts: 14,835
    and a condensate pan

    to drain any sweat from cold water hitting a hot coil. I think a Modine or any hydronic unit heater would work.



    It seems a lot simpler than tubing the roof, plus the air moving feature.



    hr
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
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