Heating water with pvc pipe

Plucka
Plucka Registered Users Posts: 130 ✭✭
edited November 2018 in Solar Beginners Corner #1
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.
Tagged:

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    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
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
     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
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    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.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • Plucka
    Plucka Registered Users Posts: 130 ✭✭

    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.

     Flag ·  Disagree  Agree  Like  LOL

  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭

    Sounds like you need a mixing valve or like that

     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • NANOcontrol
    NANOcontrol Registered Users Posts: 260 ✭✭✭

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