how to fix holes in a polyethylene/polypropylene solar heat exchanger

this solar heat exchanger is a 5m sq flat sheet consisting of two layers of black polypropylene or polyethlene (not sure which)with rows of fine bore plastic tubes sandwiched between through which water is pumped from the pool at low pressure.The water warms whilst passing through the system, then empties back into the swimming pool, hence, free pool heating. After 2 seasons of use, there are a few leaks at the joints where the fine tubes meet the main inlet tube. I tried to seal them with glass fibre, then cyano-acrylate resin...nothing stcks to this type of plastic. Any ideas for sealing these holes? The plastic is too fine to use a heating method.

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frollard8 years ago
aquarium or outdoor/ultraviolet/sun rated silicone sealant should stick. Less is more, apply a bead, then spread it into the area with a wet finger (or silicone tool)
caitlinsdad8 years ago
Is there any type of fitting that is used to join the fine tubes to the main inlet tube? I'm guessing this is rigid pipe and not flexible tubing. You would probably need to drain the system and then dry out the joint. They do sell epoxy putty for plumbing purposes that might stick to it. You could then cover the leak and wrap also it with a flexible self-sealing silicone rubber tape, also found in plumbing supplies. If it is flex tubing, you may need to cut of the worn end and reinstall the fitting. I don't know if teflon tape would help with that since they depend on the barb type or expansion fitting. Good luck.
its like that plastic corrugated board (looks like corrugated cardboard, but made of plastic) - and that is attached (thermally or sonically welded) at both ends to rigid pvc pipe, in a matching mortise. It's great as a solar collector, but not so much in the 'strength' department.
MalKnowles (author)  caitlinsdad8 years ago
thanks for your reply....silicone sealant might be the answer.
lemonie8 years ago
Have you tried Duck(R) tape or duct tape? L
MalKnowles (author)  lemonie8 years ago
thanks for your reply....yes, I tried Duck tape. It seals the leaks for a few hours, but then it peels off and water oozes out. I think silicone sealant could do the job.
frollard usually has a good answer.

L
I try...people accuse me of knowing too much - really I want know a small tidbit of ...everything possible - jack of all trades, master of none :D (except being awesome) ;)