Hot water collector
 

This has probably been talked about before but can you use the swimming pool solar heating kits to heat water for use in the house.
I'm talking about the flexible mat that is used as the collector in those kits.

Can you put that mat inside a box to use as the collector plate for solar hot water heating?
Can it withstand the temperature inside the box?

I'll take a stab at that one...

I think that High Density Polyethylene (HDPE) is used for them. HDPE has a softening temperature of about 180F.

I think that putting it in a box wouldn't be so good, because the temp could easily go over 180F.

Also, speaking for myself, I wouldn't advise using the water directly for bathing or potable use, because of the possible ill effects of plastic compounds leeching into the water, especially when it is heated.

Now, if you used one of those brazed plate heat exchangers, you'd have no worry.

My 2 cents worth.

-AC_Hacker

Thanks AC Hacker for the info, any body else, there's no way I'm the only one who has thought of this or has an opinion on it.

the water in most solar hot water panels needs to have anti-freeze in it because it also helps raise the boiling temp as well, solar hot water panels with glass enclosers often reach 200F in spots, I've seen water coming in to the house after 300 feet of piping measure 180F.

These are designed for low temperatures with enough water flow to prevent any great temperature rise, thus making them very efficient and not requiring housing in a box with glazing etc.

The proposed use for domestic water heating is fraught with problems, I have yet to see one that doesnt have the odd minor leak, as they only have push fit tubing to plastic header fittings. The other issue is the much higher sustained temperatures and softening of the plastic fittings, while the HDPE tubes themselves are reasonable resistant to heat, the other bits are not.

If you made copper headers with push fit then clamped leak proof fittings then they may work, the suggestion of heat exchanger is a good idea. There would be lesser requirement to prevent frost damage as the tubes can expand on freezing. The tubes cannot handle any great pressure, normally they lie near flat, so you may find a greater tendency for leaks as the temperature rises and tubes soften and expand.

Cheers
Mike