Priming pump emptying pool

[C3Cl3N3O3]

I have a brand new JANDY VSFHP185DA2A and am emptying the pool to prepare for the new liner. I have the skimmer line off and the bottom drain line open. I've been running for four hours at a time or so at 2750 RPM. I'm down to about a foot left (9' deep pool), and the pump doesn't seem to prime when I start it now. Just runs for about five minutes without any water flowing in before I shut it down. On the app the RPM's and power seem normal. Is this to be expected at this point? I didn't want to experiment with higher RPM's.

The pool is significantly above the water table level and was built in a backfilled area, so that's good.

 

[mknauss]

Draining a pool with the pool pump is not advised. You are endangering your pump. You need a submersible pump that is designed for the purpose.

Do not try to prime your pump with that little of water in the pool. You can damage the pump .

 

[C3Cl3N3O3]

OK how far can you safely lower your level using the pool pump? That is news to me and I was following the instructions from the pool company (not that I am doubting you).

So the lower water level requires more suction to operate then? Once the flow was stopped that last time, it wouldn't get going again. I hope the pump isn't damaged, now I'm worried. It sounded normal when it was trying to prime.

 

[mknauss]

The pump has to create suction head to prime. With your water level several feet below the pump, losing prime and destroying the pump becomes a large threat.

 

[C3Cl3N3O3]

OK so as long as it remains primed you are OK then? The risk is in running dry and overheating? I probably got lucky as I was standing right there when it lost prime and I shut it down. Thanks.

 

[mknauss]

OK so as long as it remains primed you are OK then?

Correct. As you caught it the pump should be fine. But most people do not stand next to the pool pump the entire time it takes to drain the pool. An $80 submersible pump will do the job without risk.

 

[YippeeSkippy]

You can also rent a larger sump pump from Home Depot, I believe.

Maddie

 

[C3Cl3N3O3]

I'll ask the pool company to take care of the last foot. I took care of seven feet of it. I can't see paying thousands to have this sort of work done and then having to go rent equipment myself.

 

[YippeeSkippy]

ok ..... for future reference then.

 

[Homebrewale]

I am surprised that you were even asked to lower the water level. When I had my liner replaced a few years ago, the pool company came in with their own submersible pumps and drained the pool.

 

[C3Cl3N3O3]

Yeah I often verify "pool store advice" here if I am unsure about something. No alarm bells were going off really. I guess that new pump is really getting put through its paces. It was pumping the heck out of that water right up to the point where it lost prime.

So I was able to hook up a couple hoses and get a siphon going. The pool is just high enough that I could reach a lower point in the back yard. That should get it down to four inches or so. Then I'm handing it off. Thanks gang!

 

[C3Cl3N3O3]

Here's a photo of my mess for your enjoyment. The Merlin liner ripping started in 2017 and I patched it twice with pretty good results. This year the ripping was hopeless and I just glued it to the steel wall to buy some time.

 

[Homebrewale]

Broken link to your photo.

 

[C3Cl3N3O3]

Correct. As you caught it the pump should be fine. But most people do not stand next to the pool pump the entire time it takes to drain the pool. An $80 submersible pump will do the job without risk.

Just to follow up on this, I've read the manual for this VSP and there is a note that the pump is NSF-certified as being able to prime at heights up to 10 ft above the pool water level. It also states that the pump will take 14-15 minutes to prime at this height at 2750 RPM. My equipment is below the water level, so the bottom is probably 7' down. In my case however, there is a small suction leak which I believe caused it to fall out of spec. So there appears to be an extenuating circumstance in my case, but otherwise it sounds like the pump was designed to handle this. Am I missing something?

 

[mknauss]

Just because the specs say something can be done, does not mean it is a good idea or does not increase the risk of failure.