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solar pool heater vacuum relief valve sucking air

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Posted by Larry Barowski on June 23, 2006, 7:14 pm
 
I just bought a house with a solar pool heater. The vacuum relief
valve is constantly sucking air (you can hear the whistle), and the
return lines send out a steady stream of bubbles when the solar is
on. This seems like a bad thing. Pressure at the ground-level filter
is about 20 psi and the panels are at normal one story roof height.

Does this indicate that the pump is inadequate? The pump motor
is a 1 HP up-rated.

The vacuum relief valve is located at the top of the panels. I've
read that mounting it a few feet above that on a pvc offshoot
can prevent this problem. Worth a try?



Posted by Solar Guppy on June 23, 2006, 8:31 pm
 
20psi and 1hp should be fine, mine is 20psi with 3/4 hp and works fine. Most
likely the three way valve is not fully engaged ( all flow should be
diverted to the panels ) or maybe its a home owner Joe installation and they
didn't install a three way valve and only partial flow is going to the
panels which would cause exactly the problem you describe

"Larry Barowski" <MElarrybar-AT-eng_DOT_auburnANOTHERDOTeduEND> wrote in


Posted by dold on June 23, 2006, 9:12 pm
 
What kind of filter do you have?  What backpressure is the filter currently
causing?  Is there good water flow through the filter, back into the pool?

I have a DE filter.  When it's clean, I get about 10psi backpressure,
leaving 12psi to lift water to the solar panels.  But when it is dirty, the
backpressure goes up to near 20, leving too little pressure to lift water
to solar panels.

--
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Clarence A Dold - Hidden Valley Lake, CA, USA  GPS: 38.8,-122.5

Posted by Larry Barowski on June 24, 2006, 12:14 am
 

It's a cartrige filter, which is clean. Water flow is good.

Hmmm, with the filter out the vacuum relief valve is not
sucking air. In fact, it turned up a leak in the connector
to the vacuum relief valve (rubber hose with a hose
clamp).

Here are all the pressure values at the top of the filter:

Solar On
   Filter Out  17 psi
   Filter In  22 psi
Solar Off
   Filter Out 13 psi
   Filter In  21 psi



Posted by Larry Barowski on June 24, 2006, 12:00 am
 

There is a three way valve and it looks fairly new, but
I have no way to be sure it is funtioning perfectly.



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