Heating water with pvc pipe

Plucka

90mm PVC pipe painted black to heat water results:Air temperature 35 c in the shade, water pressure 25psi and I don't know the surface temperature of the pipe.Tried to have a shower but water was too hot  so i turned the shower off but still under pressure only to hear a leak.The pipe had expanded near the inlet to such a size it's walls had become so thin that pin hole leaks had occurred.I had tried the same system earlier but with 40 psi water pressure but it blew the end off the pipe . Back to the drawing board.

BB.

From here, PVC Watt water pipe (used for garden irrigation):

https://www.engineeringtoolbox.com/pvc-cpvc-pipes-pressures-d_796.html

Note! The maximum operating pressures derates with temperature. At the maximum operating temperature for PVC - 140oF (60oC) - the strength is derated to approximately 20% of the strength at 73oF (23oC).

My Father and I would "steam" PV pipe to form into projects--Steaming (~212F) turns PVC into a "wet noodle".

Choose some other piping to make hot water... (and that withstands UV light).

-Bill

mcgivor

 A while back I made a thermo siphon system using an elevated tank with an ABS loop in a zigzag fashion using 90° fittings, feeding from the bottom of the tank to bottom og the loop, dischargeing at the top the loop was at about a 30°angle facing south. Worked extremely well, sometimes too hot, once I installed running water I changed to an instantaneous LPG water heater, for convenience, don't need much hot water due to the tropical climate, still on the first 16Kg tank after 3 years and still half full.

The problem with any plastic material is once pressure is introduced the temperature rating is reduced, ABS is better than PVC because it's already black as well as UV rated but dose have its limitations, copper or iron pipe would be better with a pressurized system, good idea is to include a pressure relief valve, just in case.

Here is some information regarding different plastic materials, temperature/pressure  ratings https://www.engineeringtoolbox.com/plastic-pipes-operating-pressure-d_1621.html

Estragon

I use this stuff for my water supply lines:
https://www.homedepot.ca/en/home/p.poly-pipe-1-inches-x-100-ft-75psi-white-stripesupsup.1000120679.html

Parts of it sit in the sun all day, and those parts get pretty warm.  One line is pressurized to 30/50psi, the other gravity system sees maybe 20psi at lake level.

I haven't used it (deliberately) for hot water yet, but this is what I plan to use when I get around to it.  Where the shower will be located will see maybe 10psi.

Plucka

Decided to give the black pvc pipe another go with a pressure regulator . 25 degrees c here today and at 2pm had a hot shower [prefect temperature].Summer is a problem because the water gets too hot and it can be well into the night before it's cool enough.The pipe now holds 20 litres.

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westbranch

Sounds like you need a mixing valve or like that

NANOcontrol

This is why I heat with PV. Everyone thinks direct solar is so simple.