At the end of the season last September the highlighted joint in the roof solar heater was gushing a fair bit of water whenever the pump was turned on.

leaking roof solar heater

The joint is now still dry. Is it reasonable to add some kind of cement or sealer on the outside? The connection is quite firm, and there does not seem to be any cracks. The plastic still looks quite young; it's not chalky. And so I'm not sure how to open it to apply the sealer/cement on the inside, short of sawing off.

That alternative, sawing off the connection and reconnecting, is a much more difficult process, and one that, I'm guessing, would risk a lot of damage. Care to comment?

  • The bottom section will always have water in it unless you reposition that bottom pipe to be lower than the bottom of the collector. That looks like a swimming pool collector anyway, a cheap option... – Solar Mike Apr 22 '20 at 5:09
  • @SolarMike Ah, of course! Thanks. If this was not properly air-pumped out of water, it may have frozen and cracked. – Sam Apr 22 '20 at 9:42
  • @SolarMike What is the right solution, or what is wrong with this solution? Is it that there is a section where water can remain despite opening the down pipe to empty? – Sam Apr 22 '20 at 9:44
  • Are those elbows 90 degree bends? They're severely out of shape if they are, and it's no surprise they're leaking. – isherwood May 26 '20 at 13:38
  • @isherwood Good catch! You saw it from just a picture, one distorting relative sizes! I take it then that this kind of elbow does not permit a bit of flexibility; is that right? Wherever it's installed, the two sides must be very close to perpendicular. – Sam Jun 4 '20 at 18:49

I doubt sealer from the outside will be any sort of long-term fix. Either the joint has come apart or one of the pieces has split. Either way you'll need to take it apart, replace any broken parts and reassemble the parts with proper solvent.

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