Pump Loses Prime From Pressure Side Airleak

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neet1nee

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Sep 1, 2013
7
Columbus, Ga.
They say you can only get an air leak on the suction side. My air leak is on the return side and is visible thru the transparent housing of the T-15 SWG (5 month old replacement for Hayward T-15 Turbo SWG) after the system is turned off for several minutes (see attached graphics). The air bubbles are visiable within the SWG and rise up into the Multiport Filter . This leakage causes water to drain back into the pool and results in the pump tank losing its residual water and loss of prime on the next start-up. There is no water leakage or wet spots. Once the system is manually primed, all components work as they should, chlorine is generated by the SWG and the Aqua Rite display functions as it should.

A local pool company was retained to determine the cause. After 3 visits and no solutions, a certified Leak Detection company was called and after 3 visits, ascertained that there were no leaks in none of the peripheral components including the vinyl lining, suction pipes, fittings, pump tank, etc. Suction lines were tested with 20 psi air pressure. Additionally, the following was accomplished: New rubber gasket and silicon lubricant on pump tank cover, inspected multi-port Spider Gasket and added new O-ring and lubricant, replaced both O-rings, lubricant and pipe tape on the SWG. I also put saran wrap on all joints (both suction and return connections) to see if the air bubbles within the SWG would stop, all to no avail.

Equipment:
20K gallon vinyl pool, Tagelus Filter Tank, Generic T-15 SWG rated for 40K gallons (installed on Feb. 25, 2019) no problems previously noted. ST-1072 3/4 pool pump and an Aqua Rite Polaris 380 pump.

pump layout.jpgSWG.jpg
 
A suction side air leak is certainly one way to lose prime to the pump, or at the very least see more air (bubbles) pulled in, but it's not the only way air gets in the system. Many times it's a leak on the pressure side that disquises itself by not leaking water. Instead, it will only pull air "in" once the system is off. This intrduction of air moves the water, often times backwards to the pool. A common place is the air relief valve on the filter (if equiped), but can be anywwhere along the lines. The visits you had appear to be comprehensive and thorough, yet something is missing. If water moves when the system is off, the pool's plumbing/air-tight "seal" has been broken and air is getting pulled-in somwhere.

I am suspect of that new (generic) cell. For testing's sake, do you have the old SWG (or SWG spacer) you could insert to see if the leak stops?
 
I'm assuming the swg has typical oring sealed unions, if this is the case you need to take if off and clean the union threads lube up the oring and do not use tape on reinstall.

It is rare but it does happen where a leak will hold pressure but not a vacuum
 
Things sure do point to that SWG cell as the air leak. Or downstream from the SWG towards the returns.
 
Based on your description, I'd say your leak is on the pressure side, from the SWG on down the line. If it were at the filter, it would drain back before you saw bubbles in the clear plastic.

I think @cfherrman is on to it, holding at pressure, but not a vacuum. If you have a blank for your SWG, id stick it in there to see if it holds.

When you are out of options, cut that line between the SWG and that sensor doo-dad and stick a valve in there, turn the pump off and close it, see which side takes on air.

If I were a betting man, I'd say its that Polaris pump, they don't like being hard plumbed like that.
 
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Texas Splash said:
A suction side air leak is certainly one way to lose prime to the pump, or at the very least see more air (bubbles) pulled in, but it's not the only way air gets in the system. Many times it's a leak on the pressure side that disguises itself by not leaking water. Instead, it will only pull air "in" once the system is off. This introduction of air moves the water, often times backwards to the pool. A common place is the air relief valve on the filter (if equipped), but can be anywhere along the lines. The visits you had appear to be comprehensive and thorough, yet something is missing. If water moves when the system is off, the pool's plumbing/air-tight "seal" has been broken and air is getting pulled-in somwhere.

I am suspect of that new (generic) cell. For testing's sake, do you have the old SWG (or SWG spacer) you could insert to see if the leak stops?


I do not have a replacement or spacer. I too am suspect of the SWG and have requested a replacement from the original vendor. Any ideas where I can find a spacer?

I neglected to state that air bubbles are sometimes visible in the pump tank as well as the SWG. The ones in the pump tank emanate from the pump side pipe not the pool suction side.
I also checked the air relief valve on the filter. I replaced and lubricated the SWG O-rings and wrapped the entire unit as well as all other accessible PVC connections. I am at a loss (other than replacing the SWG).
NeetneeO
Click to expand...
 
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Texas Splash said:
A suction side air leak is certainly one way to lose prime to the pump, or at the very least see more air (bubbles) pulled in, but it's not the only way air gets in the system. Many times it's a leak on the pressure side that disquises itself by not leaking water. Instead, it will only pull air "in" once the system is off. This intrduction of air moves the water, often times backwards to the pool. A common place is the air relief valve on the filter (if equiped), but can be anywwhere along the lines. The visits you had appear to be comprehensive and thorough, yet something is missing. If water moves when the system is off, the pool's plumbing/air-tight "seal" has been broken and air is getting pulled-in somwhere.

I am suspect of that new (generic) cell. For testing's sake, do you have the old SWG (or SWG spacer) you could insert to see if the leak stops?
Click to expand...
I do not have a replacement or spacer. I too am suspect of the SWG and have requested a replacement from the original vendor. Any ideas where I can find a spacer?

I neglected to state that air bubbles are sometimes visible in the pump tank as well as the SWG. The ones in the pump tank emanate from the pump side pipe not the pool suction side.
I also checked the air relief valve on the filter. I replaced and lubricated the SWG O-rings and wrapped the entire unit as well as all other accessible PVC connections with saran wrap. I am at a loss (other than replacing the SWG).
The air leaks only occur when the pump is off. Everything works fine when the pump has been primed and running.
NeetneeO

SOLUTION FOUND
Intermittent flow Switch operation caused the SWG not to stop generating when the pump was turned off. The SWG's continued operation with no flowing water caused it to emit it's gases which generated pressure forcing the residual water in both the pump tank and the SWG back out into the pool. Hence. the partially empty tank and loss of prime. Rewired the SWG's power to the load side of the pump's power so that the SWG losses its power whenever the pump is off.is turned off.
 
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Ok, we need to find the source of the bubbles. Pump running, you can ONLY get bubbles from the suction side. Pump Off, you can get air drawn into the pressure side but they should be flowing backwards back to the pool.

If you have any bubbles and the pump is on you have a suction side leak. Please tell us what is happening with the pump running.
 

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duraleigh said:
Pump running, that is absolutely correct.
Click to expand...
duraleigh said:
Ok, we need to find the source of the bubbles. Pump running, you can ONLY get bubbles from the suction side. Pump Off, you can get air drawn into the pressure side but they should be flowing backwards back to the pool.

If you have any bubbles and the pump is on you have a suction side leak. Please tell us what is happening with the pump running.
Click to expand...

No bubbles with pump running, entire system works OK. With pump off bubbles are visible within the SWG flowing up towards the FILTER. There are also bubbles visible in the pump tank on the pump side of the tank.
I am fabricating a spacer for troubleshooting purposes to replace the SWG and take it out of the loop. I also replaced the hose between the pump tank and the Stingl Safety Vacuum Release system. Replaced the O-ring on the pump tank drain. Haven't had a chance to re-test the system, will do so after completion of the aforementioned spacer. I will provide the results then. Thanks to all for your continued support this one is a classic and has me stumped!
Neetnee0
 
I would put a check valve between the pump and filter.

How high is the pump above the water?

I would suspect that the air leak is likely at the waste line.

I would cut the waste line and look for leaks while the pump is on and listen for suction when the pump turns off.

I would install a vacuum breaker on the waste line to help it drain. I would also install a union so that you can check for water or air leaks. Maybe install a valve to close the line securely when not in use.

Where is the Stingl Safety Vacuum Release? I don't see it in the picture.
 
Texas Splash said:
To your other question, I believe some vendors sell SWG spacers for times of the year when some wish to remove them (i.e winter). If not, you should be able to make one with a piece of PVC and a couple unions.
Click to expand...
Borrowed a Hayward OEM SWG from a pool company and replaced the one in question, same results. the pump is maintaining its prime some of the time but most of the time after approximately 30 minutes after it is turned off, the pool tank shows bubbles coming from the impeller side of the tank resulting in a loss of water.
Neetnee0

Called a different pool company to troubleshoot the problem. They stated the Multi-port Valve assembly was at fault. I replaced the Valve and it was not the problem. I also replaced the SWG again; no change. I am still seeing air bubbles in the SWG, pump side of the pump tank and the return jets. I can hear a gurgling sound in the filter pipes (when pump is off). After 2 different pool companies and a leak detection company, the problem remains unresolved. Does anyone have other suggestions?
Neetnee0
 
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