Return side draining and would like to stop it

[needsajet]

I have a Zodiac Sand Filter, model ZT650 (25") which comes with it's own multiport valve. The filter is around two feet (600) above the pool water.

The return side drains back by allowing air from the waste line past the spider gasket. After the drain line empties after a backwash, I don't see any drips, so I doubt I'm losing much water. I've checked the spider gasket and it's in perfect condition (picture below). I was warned about the Zodiac MPV but it was one of those 'pick your battle' situations with the PB. I'm kicking myself now, but c'est la vie.

So I'm looking for advice. I could put a valve on the waste line. I could try a warranty claim. Or maybe there's a better after-market spider gasket. Any and all ideas most welcome.

I think the warranty claim will result in a technician saying "no problem, system works fine" because the situation is not causing any problems.

But I don't like the SWC emptying out (or any pipe for that matter, other than solar heating) even though I can't pin down a technical reason why it bothers me. I don't like bubbles coming out of the returns when the pump starts, and I don't like the red flow light between pump runs because the SWC is empty. I have no idea if keeping the cell plates wet extends their life or vice versa. The pipes all fill quickly when the pump starts, although bubbles continue going through the SWC for a few minutes. There's a check valve on the suction side so the system doesn't drain completely to pool level and prime is maintained. I've had a leaf stuck in the suction side check valve, the system drained, but it has always primed fine and runs reliably.

 

[zea3]

Have you tried any silicon lube on the spider gasket to see if that helped? The only other thing I can think of would be to extend the waste nub enough that you could install a check valve between the filter and the waste hose.

 

[needsajet]

Thanks zea I did try silicone lube on my last feeble attempt to correct the problem and touched it up on the o-ring as well. You can probably see a bit of lube in the pic on the bottom of the diverter. I used it sparingly so I could try it a bit heavier and see what happens.

I don't have room for a check valve at the filter because the horizontal pipe is short and then goes straight down underground (I hard-plumbed the waste line in PVC). However... that's a great idea and I could put a check valve where the waste line comes up out of the ground before the upside down 'U' and air gap over the sewer gully. A new option!

I'm still hoping I can get the MPV to work the way it's meant to.

 

[JamesW]

Sometimes it helps if you lube the stem o-ring. If the stem o-ring is sticky, it keeps the spring from pushing the diverter down all the way.

You can also remove the non-metallic bearing that the handle rides on. That gives the diverter an extra millimeter push down.

 

[Pool Clown]

The valve should not be leaking, internally or otherwise, period. and should be warrantied. You may want to deal directly with Jandy/Zodiac as your PB may not want to bother, and while he should be handling it, it may be faster (service) to just go directly to the manufacturer.

 

[needsajet]

Thanks JamesW and Pool Clown. I'm still deciding and like those suggestions for service and maybe modification if need be. I was also hoping someone would say it shouldn't be bleeding air back. I don't want to unfairly rubbish Zodiac, so I'm thinking I should give them a chance to make it right.

 

[Pool Clown]

I was also hoping someone would say it shouldn't be bleeding air back.

The valve should not be leaking, internally or otherwise, period.

____________________________________________________

 

[mas985]

With solar and a VRV, the return side plumbing (post filter check valve) will drain anyway.

Is the filter draining too?

 

[needsajet]

Pool Clown, I probably didn't express my thanks properly, but I really appreciated hearing from an expert that it shouldn't leak. That gives me the confidence to chase down a warranty claim and see where it takes me.

Mark, I did the solar on an independent plumbing circuit with its own pump, intakes and returns. I'm pretty sure the filter stays full, because the SWC (which is above the filter) fills up in about 4 seconds after pump start. Here's a pic, and you can possibly see the air still working its way out of the FlowViz. After a bit of run time, the air is all gone. Thanks

 

[needsajet]

So a follow-up... after my self-imposed learning experience, it was the collar clamp - maybe not tight enough or o-ring could have had more lube (all my fault from original install). There was not the slightest drop of water coming out anywhere, but air was able to get in.

Every o-ring is clean and well lubed now, and I have a new praher spider gasket installed and the original as a spare.

I tried an extra washer under the spring for a little more force on the spider gasket. My next job is to take that out, though it's working fine.

I also now have a shutoff valve on the waste line, which I decided was kinda good as a second line of defense anyway (pool is around 45 cm or 1.5 feet above the landscape drains).

Thanks for everyone's ideas and support. I'm very happy and much relieved to hear silence

Problem solved and time to become a TFP supporter. Tick!