Immediate Pressure Loss after Pump Turns Off

[jlosurdo]

Hi there,

Earlier this spring, I had low pressure in my system. The systems had low pressure from the bubbler and consistent air bubbles from the returns.

It turned out that the 17-year-old pump basket lid had some leaks. I replaced the lid, and everything seemed to be working fine.

Last week, however, my pool stopped responding to the automation system. The "Filter" would turn off, but everything would keep running. I had similar issues in January, having the issue diagnosed as the 3HP Relay (by a professional), but due to a shipping issue, I never received the replacement part. Nevertheless, the issue went away for a while.

Last week, the system stopped responding after the automation cycle ended, or I manually tried to turn it off at the control panel and the remote control device. Flipping the circuit breaker was the only way I could get it to turn off. I have been doing this manually for the last two weeks while I waited for the part to come in. The part came in earlier this week, and I planned to replace it today.

Here is when things get weird, and I don't know where to troubleshoot.

Last night, my daughter wanted to use our spa, so I manually turned the pool on, flipped it to spa mode, turned the heater on, and everything worked. When they were done, I turned the heater off, put it back to pool mode, and then turned everything off with the circuit breaker. Fast forward to this morning, I replaced the relay, which was pretty straightforward; however, when I went to turn the pump on with the controller, it came on, but the pump had lost its entire prime. I go through the procedures to get it primed again, and it starts humming with very strong pressure. But...when I turn it off, there is an immediate "whooshing" noise, and the system's pressure disappears almost immediately. I then have to prime it to get it going.

Do you have any ideas at all? I don't know if something happened when I switched to spa mode last night (for the first time all season) or if there is another issue. I don't think it is the lid because when the pump is running, the pressure is perfect.

Any help is appreciated before I call a pool tech and spend a bunch of money. Thanks.

 

[1poolman1]

Hi there,

Earlier this spring, I had low pressure in my system. The systems had low pressure from the bubbler and consistent air bubbles from the returns.

It turned out that the 17-year-old pump basket lid had some leaks. I replaced the lid, and everything seemed to be working fine.

Last week, however, my pool stopped responding to the automation system. The "Filter" would turn off, but everything would keep running. I had similar issues in January, having the issue diagnosed as the 3HP Relay (by a professional), but due to a shipping issue, I never received the replacement part. Nevertheless, the issue went away for a while.

Last week, the system stopped responding after the automation cycle ended, or I manually tried to turn it off at the control panel and the remote control device. Flipping the circuit breaker was the only way I could get it to turn off. I have been doing this manually for the last two weeks while I waited for the part to come in. The part came in earlier this week, and I planned to replace it today.

Here is when things get weird, and I don't know where to troubleshoot.

Last night, my daughter wanted to use our spa, so I manually turned the pool on, flipped it to spa mode, turned the heater on, and everything worked. When they were done, I turned the heater off, put it back to pool mode, and then turned everything off with the circuit breaker. Fast forward to this morning, I replaced the relay, which was pretty straightforward; however, when I went to turn the pump on with the controller, it came on, but the pump had lost its entire prime. I go through the procedures to get it primed again, and it starts humming with very strong pressure. But...when I turn it off, there is an immediate "whooshing" noise, and the system's pressure disappears almost immediately. I then have to prime it to get it going.

Do you have any ideas at all? I don't know if something happened when I switched to spa mode last night (for the first time all season) or if there is another issue. I don't think it is the lid because when the pump is running, the pressure is perfect.

Any help is appreciated before I call a pool tech and spend a bunch of money. Thanks.

Single-speed pump? How large? When was the filter last cleaned? What is the pressure on the filter tank when running?
If the filter is dirty, or it is in spa mode with water trying to go through the 1/4" spa-jet orifices, the excess pressure in the system will go somewhere when the pump turns off. The path with least resistance is back through the pump and into the pool. It will take the water in the pump with it.
You need to find out why there is so much pressure.
With the pump on you may even see the filter tank expand a bit.

 

[jlosurdo]

Thanks. I don't think it is the lid. Before I replaced the old lid there was a bunch of bubbles coming out of the returns consistently and the water pressure was super low. These symptoms are very different. I can almost hear the pressure immediately get lost when the pump gets turned off.

 

[Bperry]

Thanks. I don't think it is the lid. Before I replaced the old lid there was a bunch of bubbles coming out of the returns consistently and the water pressure was super low. These symptoms are very different. I can almost hear the pressure immediately get lost when the pump gets turned off.

You probably already know this, but the salt water chlorinator makes bubbles come out of the returns. Just thought I’d bring that up to make sure it’s not confused with another problem.