Another annoying mystery leak

Last summer I gave up on my improvised solar water heater because it sprang a theoretically impossible but quite substantial leak. This morning I pulled all the innards down to see if I could find it.


It’s just good quality black garden hose. Not made for the temperature in that box, to be sure, but it really shouldn’t leak until the hose completely deteriorates – and then it should unmistakeably leak.

I pressurized it, no leak. Left it out in the sun all day. No leak. So why was it leaking before? Tomorrow I’ll put it all back together and see how long it works. It’s kind of handy, if only the water would stay where it belongs.

About Joel

You shouldn't ask these questions of a paranoid recluse, you know.
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5 Responses to Another annoying mystery leak

  1. Mike says:

    I don’t remember if you wrote that the metal hose connectors were under the plexiglass or outside of it. So, if the metal connectors are on the outside of the box, I’m stumped.

    But, if the metal connectors are under the plexiglass that could be the problem. As the metal heats up under the plexiglass in the sunlight, the metal expands enough to let water leak around the gasket. The heat under the plexiglass is a lot more than just letting the hose sit in the sun.

    I hate closed door mysteries.

  2. Fred says:

    I read about your solar water heater. I’m gonna build one for my RV. But I’m thinking for the part exposed to the sunlight I’m gonna use copper tubing and braze or solder pex fittings on it. And either use PEX to attach to existing plumbing or possibly silicone tubing. Not sure but it’ll soak up a lot of heat with deadhead pressure. And I’m thinking about adding a pressure blowoff to the circuit because if they put them on water heaters it’d be a good to have one in my homemade system. Keep us posted on your progress. Thanks, Fred

  3. Joel says:

    …if the metal connectors are under the plexiglass that could be the problem.

    I’m pretty sure that is the problem. The only seepage I got overnight was from one of the fittings. I’ve tightened them all and put the whole thing back together, but I think it’s just going to leak again when the pressure exceeds spec.

  4. Michael Gilson says:

    Maybe you need to put something in the system that functions like the overflow tank on a car’s radiator?

  5. Mike says:

    Fred – PEX is not suitable for this type of installation. In sunlight it degrades very quickly. In a matter of a few months the PEX would be unusable.

    Joel, one simple fix maybe to replace the plastic washers that come with the hose with thick rubber ones. If that fails you may want to try reinstalling the hose so the connections are outside the box where it’s cooler. Otherwise I can’t see anyway around this problem. Good luck.

To the stake with the heretic!