Weird Priming Issue

Jump to latest Follow Reply
J

JustPeachy

Member
Mar 16, 2022
11
Virginia
Pool Size
35000
Chlorine
Liquid Chlorine
Hello all, I'm trying to diagnose a weird issue I have with my spa losing prime. Been this way since ive owned the pool (3 years).

Pool primes and keeps prime indefinitely with pump off

Pool & Spa primes and keeps prime indefinitely with pump off

When turning off pool suction while both are running and primed, after about ten seconds air begins to enter the pump, and within a minute there is a massive air bubble, regardless of pump rpm. Spa has a single drain at the bottom.

Could this be because the drain is only 4 feet underground and the ~700 gallons of weight doesn't "push" enough water through the spa suction drain? Could this be because of an air leak, even though it holds prime?
 
Sure thing.

The spa suction line is closest to the pump. There is no valve for pool skimmer/drain.

IMG-3787.jpg
IMG-3786.jpg

I could not find any leak above ground using the hose method (have had success with that in the past).
 
Last edited:
Just,

Seems to me that when you are running with just the input from the spa, the pump can not suck enough water to keep the pump happy.. I would assume that your spa drain is partially clogged, or maybe the pipe collapsed, or maybe something is in the spa diverter valve is clogged or broken.

I would take the spa intake valve apart, to see what it looks like and then I'd stick a bladder in there and force water backwards into the spa drain and see what, if anything, comes out.

Thanks,

Jim R.
 
  • Like
Reactions: Nonyabiz and JustPeachy
Jimrahbe said:
Just,

Seems to me that when you are running with just the input from the spa, the pump can not suck enough water to keep the pump happy.. I would assume that your spa drain is partially clogged, or maybe the pipe collapsed, or maybe something is in the spa diverter valve is clogged or broken.

I would take the spa intake valve apart, to see what it looks like and then I'd stick a bladder in there and force water backwards into the spa drain and see what, if anything, comes out.

Thanks,

Jim R.
Click to expand...
Great suggestions, thank you. I can get air back through the spa drain when I winterize (IIRC). I'll check both the spa valve and the spa drain, since its easy to get to.
 
  • Like
Reactions: Jimrahbe
Jimrahbe said:
Just,

Seems to me that when you are running with just the input from the spa, the pump can not suck enough water to keep the pump happy.. I would assume that your spa drain is partially clogged, or maybe the pipe collapsed, or maybe something is in the spa diverter valve is clogged or broken.

I would take the spa intake valve apart, to see what it looks like and then I'd stick a bladder in there and force water backwards into the spa drain and see what, if anything, comes out.

Thanks,

Jim R.
Click to expand...
Well, I took apart the diverter valve (was completely fine), and drained the spa and took off the drain cover. The drain had really strong suction against my hand, and the cover is rated at 125 gpm. There was no major blockage close to either end.

Not sure if I can really do anything else
 
Just,

Do you have flex pipe under ground or regular PVC?

I still feel the problem is that the pump can't suck enough water through the spa valve. Obviously, it could be something else, but I can't think of what it would be, since everything else seems to work the way it should.

Please let us know what you find, as it will help me, and any future readers, about what could cause your issue.

Thanks,

Jim R.
 
  • Like
Reactions: m_cat12
JustPeachy said:
Well, I took apart the diverter valve (was completely fine), and drained the spa and took off the drain cover. The drain had really strong suction against my hand, and the cover is rated at 125 gpm. There was no major blockage close to either end.

Not sure if I can really do anything else
Click to expand...
On both valves before the pump it would be good to replace all three O rings (two stem, one body). For a quick test, open the valves, remove the stem O rings, lube the shaft, replace the O ring, put lube on them then wrap a couple of layers of Teflon tape around the O rings and lube again. Be sure to put some lube on the body O rings a well and re-assemble. Don't use a power tool to tighten the lid screws and alternate tighenting like you would an automobile wheel, in a "star" pattern.
 
Jimrahbe said:
Just,

Do you have flex pipe under ground or regular PVC?

I still feel the problem is that the pump can't suck enough water through the spa valve. Obviously, it could be something else, but I can't think of what it would be, since everything else seems to work the way it should.

Please let us know what you find, as it will help me, and any future readers, about what could cause your issue.

Thanks,

Jim R.
Click to expand...

No flex pipe that I know of, just a single drain with about 30-35 feet of 1.5 inch to the pad.
1poolman1 said:
On both valves before the pump it would be good to replace all three O rings (two stem, one body). For a quick test, open the valves, remove the stem O rings, lube the shaft, replace the O ring, put lube on them then wrap a couple of layers of Teflon tape around the O rings and lube again. Be sure to put some lube on the body O rings a well and re-assemble. Don't use a power tool to tighten the lid screws and alternate tighenting like you would an automobile wheel, in a "star" pattern.
Click to expand...
Wouldn't the pump lose prime while off if that was the issue?
 

Enjoying this content?

Support TFP with a donation.

Give Support
JustPeachy said:
No flex pipe that I know of, just a single drain with about 30-35 feet of 1.5 inch to the pad.

Wouldn't the pump lose prime while off if that was the issue?
Click to expand...
Wanted to update this thread because I have resolved my issue. I started to suspect towards the end of last season that the issue was the length of straight pipe from the spa inlet before the front of the pump. There was only 3.5-4ish inches to the pump.

I changed my plumbing this year by moving my pump back, and now have about 12 inches between the spa inlet and pump. Also added a three way diverter valve for the pool and spa before the pump.

No more issues keeping the pump primed.
 
  • Like
Reactions: m_cat12, ScudBar61 and Texas Splash
Barack Obama Applause GIF by Obama
 
  • Like
Reactions: m_cat12 and JustPeachy
JustPeachy said:
Wanted to update this thread because I have resolved my issue. I started to suspect towards the end of last season that the issue was the length of straight pipe from the spa inlet before the front of the pump. There was only 3.5-4ish inches to the pump.

I changed my plumbing this year by moving my pump back, and now have about 12 inches between the spa inlet and pump. Also added a three way diverter valve for the pool and spa before the pump.

No more issues keeping the pump primed.
Click to expand...
Can you post after pics? Having a hard time visualizing
 
JP,

I am glad you got er fixed... :goodjob:

But... there are thousands and thousands of pool pumps out there, which only have an inch or two of straight pipe before the pump, and they all work just fine..

I suspect there is more to the story that actually fixed your issue... :mrgreen:

Thanks,

Jim R.
 
Jimrahbe said:
JP,

I am glad you got er fixed... :goodjob:

But... there are thousands and thousands of pool pumps out there, which only have an inch or two of straight pipe before the pump, and they all work just fine..

I suspect there is more to the story that actually fixed your issue... :mrgreen:

Thanks,

Jim R.
Click to expand...
Last season I tested for air leaks extensively, and even drained the spa completely and tested the plumbing path to the pump with a fish tape. No blockages I could find, and air and water were both able to travel freely.

The only variables I changed are +1 3-way, and + 9ish inches more pipe prior to pump.

I think there was too much turbulence between spa side and pump and it wasnt able to suck the volume required. Isnt there a reason the pump manufacturers say to have 1.5x pipe diameter prior to pump housing?
 
You must log in or register to reply here.
Top Bottom
Back
Jump to latest Follow Reply