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Solar DHW piping insulation

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Posted by Glenn on February 25, 2004, 1:09 pm
 
What do you use to insulate outdoor piping runs on a solar hot water
system ?
I am considering plumbing my collector loop with pex tubing but it must
be 100% protected from UV or it will fail.  Its shyness notwithstanding
I do like the idea of a single tube (no joints) from my collector to my
pump and heat exchanger.
I know of the typical black foamy pipe insulation, but don't know how it
would perform in an outdoor application.  My climate includes massive
rainfall, occasional snow and moderate summers.

Any and all suggestions, experiences, and pricing data greatly appreciated.

Glenn


Posted by John on February 25, 2004, 1:26 pm
 

: What do you use to insulate outdoor piping runs on a solar hot water
: system ?
: I am considering plumbing my collector loop with pex tubing but it must
: be 100% protected from UV or it will fail.  Its shyness notwithstanding
: I do like the idea of a single tube (no joints) from my collector to my
: pump and heat exchanger.
: I know of the typical black foamy pipe insulation, but don't know how it
: would perform in an outdoor application.  My climate includes massive
: rainfall, occasional snow and moderate summers.
:
: Any and all suggestions, experiences, and pricing data greatly
appreciated.
:
: Glenn
:

Glenn,

FWIW, cover the pex with foam pipe insulation, then slip PVC pipe over the
foam and seal the PVC.

John



Posted by SQLit on February 25, 2004, 1:53 pm
 

Depending on where you live, like the American Southwest deserts, NIX on the
PVC (pex) exposed to the sun. PVC even schedule 80 will only last 5-7 years
on your roof. Not sunlight resistant.
My old system was run in soft copper to the roof. The changed to hard
copper. If you silver solder it, there should never be a problem. Until the
foreign object falls on it. Yea it happens some times.  I would challenge
that the pex tubing is not rated for the temps that the collector can
generate. I know my Lockenvar water heater had higher specs than the average
residential water heater.   I had water temps over 170F in the summer,
granted it was 115 outside.

My copper pipes were insulated with the closed cell foam product. The home
stores some times only carry the open cell. You might have to get it from an
HVAC supplier. Try Johnstone or WW Grainger.  Do not buy the stuff that is
split and has self sealing tape. It will not hold up. Use a good quality
black duct tape and you will only need to check the seams once a year. I had
my system 9 years and only replaced pieces on the roof 3 times. Did some
taping usually every year.



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