Pump damage- dry running

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UKjames

Silver Supporter
May 1, 2020
275
United Kingdom
Pool Size
44000
Surface
Vinyl
Chlorine
Liquid Chlorine
Hi all

I hope you’re all good.

I don’t close the pool over winter, just run the pump a few hours a day.

stupily though I let the level drop a bit low without keeping too much of an eye on things. It didn’t drop below the skimmer but the suction meant the level wasn’t enough to feed enough water. Result pump and filter dry and I didn’t notice.

I’m not sure when this happened so my pump might have been running dry for a couple of hours a day for a week or more.

Topped up the water now and primed the pump.
All seems ok - but I’m guessing I’ve probably shortened the life of the pump?

Seems to be taking a while to fill the sand filter though. I stopped the pump and all the water seemed to drain back out - I put this down to the sand filter not creating a vacuum or something. Re primed and running again. No air in the pump, quite a bit in the filter but going down slowly I think.

Feel a bit silly for not checking it!

Don’t heat the pool in the winter and evaporation seems greatest which I struggle to get my head around!
 
UKjames said:
All seems ok - but I’m guessing I’ve probably shortened the life of the pump?

Seems to be taking a while to fill the sand filter though. I stopped the pump and all the water seemed to drain back out - I put this down to the sand filter not creating a vacuum or something. Re primed and running again. No air in the pump, quite a bit in the filter but going down slowly I think.
Click to expand...
Are you getting air coming out of the returns when the pump is running? Does the pump leak, at all, at the connecting point between the motor and the volute (answer both for pump on and pump off)? When you open the air bleed valve on the filter, can you hear air coming out?

What is the make and model of the pump and filter? Can you post a picture of your equipment pad?
 
Hey - thank you

I’m not sure I have a bleed valve. It’s a lacron sand filter. Or it I have one I’m not sure where it is or what it looks like. It has a viewing glass on the top and I can see the air in that. Pool covered so not noticed return air. Will need to check.

I don’t think I have a leak suction side as the pump filter Basket purged bubbles quite quickly.

Not sure on the join between motor and pump. Last time I took it apart I had a real job trying to seal the join. I’ll need to check in Day light to see if it has failed now - not a big fail if it has as didn’t notice masses of water around.
 
UKjames said:
I don’t think I have a leak suction side as the pump filter Basket purged bubbles quite quickly.
Click to expand...
A shaft seal leak is a suction side leak and you may not see water in your basket. That is the only think that would likely result from running it dry. Some seals can run for a number (10+/-) without damaging the seals. Other seals can't handle it and fail. Probably the only way you would know is a leak at the joint between the pump and the motor (where the seal is) when the pump is off, or getting air coming out your returns while running, after your filter has purged whatever air it can.

On the other front, I'm trying to figure out if that filter "autopurges," there is a purge valve, or it just works with air in it. Would need to Model# to figure that out.

It is likely you are ok, if there is no water coming from the pump, and you are not getting air out the returns.
 
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You probably want to replace the broken pressure gauge. Here is the startup procedure. Are you following this? Likely why you are seeing air in filter:

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Thanks JamesW you found some pics I couldn’t find!

Although that’s my spare pump I’ve got a slightly different one on there at the moment. I tried to replace the pump/motor seal as had a very small leak but ended up with a big leak with the new seal and couldn’t fix it, so I took the starite one off. The one on at the moment is a French made one, ancient again.

I don’t think there is any valve. After running for several hours, there’s now a lot less water in the filter and the pump stays primed when off. Or at least it did for a few minutes, hopefully will stay that way!

Yes good reminder on the gauge they don’t last very long. I ordered one from the big A but didn’t show up. I’ll chase/order another.
 
UKjames said:
Hey - thank you

I’m not sure I have a bleed valve. It’s a lacron sand filter. Or it I have one I’m not sure where it is or what it looks like. It has a viewing glass on the top and I can see the air in that. Pool covered so not noticed return air. Will need to check.

I don’t think I have a leak suction side as the pump filter Basket purged bubbles quite quickly.

Not sure on the join between motor and pump. Last time I took it apart I had a real job trying to seal the join. I’ll need to check in Day light to see if it has failed now - not a big fail if it has as didn’t notice masses of water around.
Click to expand...
Your pump is a Max-E-Glass 1 pump, very durable. They were still being made up to about 3 years ago for this country (.5hp only). If it is old enough, it should have a copper cone in the sealplate that the PS-100 seal cup goes in to. If it isn't there it takes a PS-200 seal. That works as a heatsink to protect the pump itself, but the seal can still be damaged from running dry and should be replaced so as to not cause bearing damage to the motor.

The easiest way, obviously, is to remove the pump from that dismal location and work with it on a bench. When reassembling, be sure to use lube on the diffuser O ring to facilitate it seating in the volute. Always use a new sealplate O ring. Always. When tightening the clamp, lightly tap on the clamp near the bottom and work your way around so that the ends of the clamp are about 13mm (.5in) apart.

Be aware that there can also be a suction (and water with the pump off) leak between the hair and lint pot and the volute.
 
Thank you! I think that means I have auto bleed on it?! I must admit I’ve never knowingly bled it and it usually purges air eventually. Never had that much air in it though.
 
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I seem to be pretty rubbish at having success when following instructions that involve something water or air tight. I can’t work out what I’ve done wrong with the sta pump and volute (I assume this is the wet bit). But the two no longer go together happily enough to be completely leak free. I decided against replacing any other o rings at that point for fear of causing more damage!
 

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