Replacing a motor on a pump, and getting the correct size for your pool?

[mitchryan912]

I installed a vacuum gauge on the basket side today, and on its own, it wasn't able to get much more than 1 mm Hg. Later in the day, I stuck a drain king into the skimmer and had it blasting water towards the pump, and only then did it shoot up to 20+ mm Hg. The motor still kept shutting itself off before it was able to get full prime though.

[mitchryan912]

It ran just fine for a week before I changed some of the plumbing around. It would be easy to say THAT is the problem, but since we've owned the house, THREE motors in three different plumbing configurations have had problems that caused a motor to stop working. The pump that came with the house worked in the fall we bought the house, but then didn't start up the spring after. The replacement pump worked for a year, but then that motor failed. Now the new replacement motor that we bought on July 20th has died.

I've emailed the company I bought it from in hopes there is at least a 30 day warranty on it.

[CarlD]

Unfortunately it seems that one of two things is very wrong, possibly both.
First: there's got to be a problem with your plumbing, somewhere. But it's beyond me--I can handle the simple stuff and I always keep it simple.
Second: You may have a wiring problem, possibly trying to run a 220v pump at 110v or something more subtle.

I doubt it's the pump/motor itself. Not sure what, if any, guidance I can give you. You'll have to rely on Mark for that.

[mitchryan912]

Could the suction line simply be too high up for 1.5" flex PVC running back to the pool? I installed these 2" lines with the ability (hopefully) to hook them up to new 2" hard PVC when the next time we have to do major upgrades to the pool.



Or could a 70' 12 gauge run to the pump not be enough wire? Everything I'm seeing says that it is sufficient, but there's part of me that thinks it's just not enough.

The former is a PITA repair, but one that can be done. I pretty much have to trash everything I did, or use the inside 1.5" slips on the 3-way diverter valves I just bought. The latter is a $4000+ repair, as the main panel in the house needs to be upgraded before any electrician is going to run anything to the shed/pool.

[mitchryan912]

Could the previous motor failure have gotten the wet end hot enough to melt/deform it? I noticed last night that I could still see a small gap between the flange that's inbetween the suction side of the pump and the motor:



I poured water over it while it was running, but that didn't seem to do anything. I didn't feel any air being pushed out of the cavity either.

[CarlD]

I cannot answer your questions but when I had my pool pump wiring installed, it was 10 gauge wire. And when I extended it, I used 10ga as well with no problems.

[mitchryan912]

I borrowed an ammeter today, and measured a draw of 19A on high and 4-5 on low, on each leg. I don't know much about motors, but that seems excessive. I could see a startup draw spiking really high like that, but not a sustained draw 3x higher than the motor rating.

[mas985]

Yes that is excessive and likely due to interference somewhere in the wet end. If the pump was run without water flowing through it for too long, the water can heat up and deform the wet end causing an interference issue with the impeller. But usually you will hear that when running the pump.

[mitchryan912]

I did just take everything apart to get things ready for a warranty replacement motor to arrive tomorrow. I did notice the above, that this seal was slightly crooked. Could this cause a major problem?

I never noticed any odd sound until just after I hooked up the pump to some plumbing I re-did (took out two shutoff a and replaced them with a pair of 3-way valves.) Everything seemed fine until a few minutes after running the pump. It was struggling to reach full prime, and it might have been because the water level was too low (pulled all the water out of the skimmer), so I shut it off and filled the pool up a few extra inches over the course of 3 hours. Turned it back on later that night and it sounded really funny, with a sort of him to it like it was seizing up.

FWIW, the pump had run fine for a full week up until I decided to change up the plumbing in an attempt to convert a vac line to an either/or line (vac or return.) There may have been a problem in the height of the new plumbing to the first valve, which was about 8-10" above the pump intake port.

[mas985]

I think you may have the seal in backwards. The ceramic end (white) goes into the motor mounting plate with the ceramic facing towards the impeller. The carbon side (black) faces the ceramic on the impeller side.

And yes, the surfaces must be perfectly parallel and flush or it will ruin the seal and cause friction issues.