Check valve location with new pump and solar heating panels

[Lmuggs]

I recently upgraded several components for our pool when a Jandy SWG needed to get replaced. I had a Hayward AQR925 put in, a new Pentair VS pump and heat pump as well. I'm a new pool owner (for the last year) and previously used a service but recently decided to start maintaing everything myself. The system has a solar heater as well. The question I have is, there was a check valve on the distribution side of the old pump. The installer said that was an odd place for it and has never really seen one there before so when the new pump was installed he did not put a check valve there. After reading several posts my initial thought is that it was there to either help the pump not lose prime or also to stop the solar heater grids from emptying and back flowing through the filter, pump and out the drain / skimmer (basically going in reverse) when the pump is off.

The manual for the pump says "Use a check valve in the discharge line when using this pump for any application where there is significant height to the plumbing after the pump". I'm probably answering my own question but I'd like to see if people that have more experience think its a good idea to have a check valve there as the manual states or not. I've included 3 pictures. One before the upgrade that has the check valve in place, another with the new components (without check valve) and also a look at the solar return pipe that has its own check valve.

Thanks for any insight!

Old (with check valve):

New (without check valve):

Solar:

 

[domct203]

Welcome to the forum!

Unfortunately PhotoBucket is holding your pictures hostage, I can't see any of them.

 

[Lmuggs]

I think there must have been a change to PhotoBucket. I've changed them to actual links instead of embedded URL's

 

[SoCalGuy]

Still no pics.

 

[Lmuggs]

3rd times a charm. Couldn't get PhotoBucket to work so I've made the file size small and uploaded them locally

 

[Lmuggs]

So in case anyone else has a similar issue or is curious. I just spoke to the original installers of the solar heater and they said that they put the check valve on the distribution side of the pump for just this reason. To prevent DE and other debris from flowing in reverse from the filter to the pump when the system shuts down at night. They place it there specifically for DE filters. For cartridge filters it would be after the filter.