Missing check valve?

[josh1014]

When I switch into spa mode via iaqualink, my filter pump stops, my suction side JVA switches from pool suction to spa suction, and my return side JVA switches from pool return to spa return, then the filter pump starts up. The timing was setup properly so that the JVAs complete their movement before the pump starts.

I’ve noticed that during this transition period, my spa water level drops 1/4”. My spa loses no water during spa mode operation, or when dormant. Essentially, every time I cycle into spa mode, I lose 1/4” of water from the spa presumably into the pool and then another 1/4” going out of spa mode back to pool mode.

I believe the issue is a missing check valve on the suction side that would prevent backflow of water from my spa floor drain line to my pool floor drain line during that brief period where the two are connected while the JVA is turning. It appears that issue probably doesn’t happen on the return side because there is a check valve to prevent it. Am I correct and I should have the PB put a check valve where I indicated in the attached photo? Or do I still have much to learn about plumbing?

Thanks!

 

[Jimrahbe]

Josh,

You can just set your system so that the pump does not shut off when the valves move..

Also, even if the spa drains 1/4" when you use it, it should just fill right back up the next day when in the pool mode.

I guess I don't fully see the problems??

Thanks,

Jim R.

 

[josh1014]

I have an autocover on the pool, so my “pool mode” does not include a spa spillover. I engage that manually whenever the pool is actually open.

My normal operation is 11 hours of pump time in pool mode and 1 hour of spa mode daily. If I don’t actually use the pool or engage spillover all week, then essentially my spa just drops 1/2” per day from the cycling. You’re correct that it isn’t the biggest deal in the world, invariably I will use the pool eventually to fill it back up, but am I correct that a check valve would eliminate the issue entirely?

Setting it to keep the pump on during the transition as you suggested would also cause some sort of water shifting between pool and spa, just not sure I could guess which side would win in that scenario.

 

[josh1014]

Is anybody able to confirm that a check valve placed as indicated on the attachment would eliminate this? Thanks!