Hayward PSV3S2 leak down for solar purposes?

Thanks Jason. I now have a check valve question. If the solar is completely closed why do others put the check valve after the filter and before the 3 way? In other words, how can water push back thru the filter if solar is off? I'd rather not add the check valve if not needed but it seems everyone does it and I am wondering iof they have a different set-up than me. Thanks!
 
With a traditional plastic solar heating setup a vacuum release valve is needed for the drain down. Otherwise the weight of the water trying yo go down would pull a vacuum at the top and when the plastic is hot and soft this can crush the little tubes.

The check valve by the filter prevents the drain down water from backing through the filter when the pump is off.

Posted with Tapatalk ... sorry if I sound short ... hate typing on phone :)
 
The drain down typically happens through the return pipe, which doesn't have a valve on it. It can also happen on the diverter if it is a leaky diverter. That creates pressure both towards the pool returns and backwards towards the filter. It is important to have a check valve to prevent the filter from sending debris back into the pump.
 
If the solar valve is not actuated and you leave it on solar when the pump goes off, water will drain back down both solar pipes and back through the filter.

If the valve is actuated, it will close the solar when the pump goes off usually. So the water up water will be trapped if the valve does not leak. But the down pipe will drain down and push back into the filter through the solar valve.

So seems like there is always a possibility of washing back through the filter that could be solved by adding the check valve.

Posted with Tapatalk ... sorry if I sound short ... hate typing on phone :)
 
Yes, you need a check valve after the filter.

Water can always drain down from the solar return pipe regardless of any check valve there. That check valve is designed to prevent water from going back up into the panels backwards when they are off and the pump is running. It doesn't block water from coming down the solar return pipe (if it did the panels wouldn't work).
 

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