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no solar heat

I have a closed looped solar hot water installation from Heliodyne. It has a small pv pump that circulates hot water down to a heat exhanger on the outside of the 80 gallon tank. Problem is that there doesn't seem to be any thermosiphoning going on. Supply and return lines from the roof heat to 180 or 190 degrees these days. PV pump seems to be working well. But there is no hot water in the tank. What can possibly be interrupting the thermosiphon process?


  • Duncan_2
    Duncan_2 Member Posts: 174

    Are there check valves are in the system to prevent hot water in the tank thermosiphoning up to the panels and radiating the heat to the night sky? It's possible one has jammed closed or partially closed.

    How high up are the panels? Are you sure there's no air trapped at the top of the panels? Is there an air eliminator at the high point? What's the system pressure? Tube-in-tube or brick heat exchanger?

    Describing the system in more detail would help.

    Describing the problem in more detail would help, too. Did it quit working suddenly... gradually? Did it make any noises?

    Your statement "PV pump seems to be working well" is puzzling. How did you determine that? What kind of voltage AND current are you seeing?
  • hr
    hr Member Posts: 6,106
    Sounds like you have

    one of these long tube HXs? The solar loop from the panels goes into the side connections and the DHW from the water heater tank is in the large diameter part of the tube. The only pump is the one that circulates through the solar panel.

    I would check for an air lock at the top of the tube on the DHW side. Is there a union connection you could lossen a bit to bled an air bubble?

    These tubes are simple but effective. I used this homemade one on my solar DHW at my shop. Works great. They are common in the wood furnace industry for DHW production with an exisiting tank, also.

    hot rod

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  • Larry_7
    Larry_7 Member Posts: 86
    Now That

    installation is what I call a real "Wallie"... Oh, the pic is sideways. Never mind...Happy Thanksgiving all!

  • Robert O'Connor
    Robert O'Connor Member Posts: 97
    How much

    How much heat transfer would you expect thru that arrangement? I need a hx for a garage loop with antifreeze. Load is about 30 k . Would that arrangement work? Heat source is a boiler.

    Thanks for your input.

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