Solar Gravity Drain Back Question

[bhollehday]

My pool equipment is located at a lower location then my pool, there is always a positive pressure on my inlet and outlet side of the equipment. I am installing solar right next to the equipment on a slope. I thought at first I might be able to drain some of the panels when pump is turned off since 80% of the panels are above the equipment, but the more I think about it, the more I don't think I even have a chance of draining anything since there is always a positive pressure on inlet/outlet of equipment from being below the pool. I'm thinking about not getting a drain back valve, and not using CPVC on anything, but the outlet pipe of the panels, which will save a lot of money! Id still put a vacuum breaker on the top and a manual drain at the bottom, but just plan on always running the solar 20%-100% open.

Anyone agree or disagree here?

 

[mas985]

The panels need to be above the pool water level to drain back to the pool.

 

[bhollehday]

Got it. So if that's the case I don't need a 3-way drain back valve. I need a manual 2-way drain valve and a vacuum breaker. And I need to drain the panels when temps are high to prevent high stagnation temps, or else leave at least a little water flowing through the panels at all times to keep temps in the panels down?

The big question I have is if I can use PVC instead if I plan on always leaving a small amount of flow through the panels in the summer time, or else draining them?

Or for the feed line of the panels use PVC and CPVC for the return (I cant imagine temps getting above 140F if your always running some water through)? It gets 110+ out here in the summer time. Panels are east facing and only get about 6 hours of full sunlight.

 

[mas985]

As long as there is water flowing through the panels, you shouldn't need to drain them. PVC will soften above 140F but the issue of collapsing pipe would not occur in your case as the pipes are always under pressure although the pipes could warp a little.

However, it is still probably a good idea to have the ability to drain when necessary for maintenance. But that also means that you will probably need isolation valves for solar.

 

[bhollehday]

As long as there is water flowing through the panels, you shouldn't need to drain them. PVC will soften above 140F but the issue of collapsing pipe would not occur in your case as the pipes are always under pressure although the pipes could warp a little.

However, it is still probably a good idea to have the ability to drain when necessary for maintenance. But that also means that you will probably need isolation valves for solar.

Ok so do you think I could even just get away with using PVC rather then CPVC? Fittings and pipe are really expensive so would like to avoid if I can.

I will add a tee to the bottom of the panels with a 2-way valve for draining.

You say probably need isolation valves, is that because you dont want to rely on the backflow valve isolating the outlet end of the solar? The 3-way valve could isolate the inlet end of the solar...

 

[mas985]

I wouldn't bother with cpvc.

The return check valve could be used for isolation as long as it is working properly.