pump motor tripping breaker

[horn1993]

Hi -

First time poster looking for some advice here. I'm pretty handy around the house and wanted to take a crack at repairing my pool pump / motor. It has stopped running for well over a month now and whenever I reset the house breaker and turn it on, it flips the breaker in the main house electrical panel as soon as it starts to run. One time I observed a large "WHOOMP" sound and a small flash from inside the motor housing as it happened.

I'm assuming something is causing it to short the circuit and am looking for advice on how to diagnose and/or fix.

The set up -

Live in Dallas, TX (and praying the recent ice didn't freeze anything beyond repair - pump stopped working before this...)
In ground pool - approx 14k gals
DE filter
pump is Century Centurion with 2 HP A.O. Smith (approx. 3 years old)

Thanks in advance for any help.

 

[Riles_J]

That is exactly how my pump was behaving. I purchased a new motor and replaced it and it works great. If you are a little handy then this certainly a job that you can do. It took me about an hour, but that was only because it took my a while to figure out how to get the mounting bracket off the existing pump. There really is not much to it.

Good luck.

riles

 

[duraleigh]

Welcome to the forum. I'm not any help troubleshooting your motor.

In the event you end up with a new one, 2hp is awfully big for your pool. I haven't done the math but .75 or 1HP should be perfectly adequate, do a better job, and save you some money.

 

[horn1993]

Thanks for the input. I've always thought that this was too big of a motor. It was replaced a few years ago when the original failed and the repair guy just picked a bigger motor (with no input from me... and at the time, I didn't know enough to ask).


So two other questions -
1. Any recommendations on replacement brands / stores? I've read posts here that say A.O. Smith is no longer a good choice.

2. Is there a resource somewhere on this site to calculate the proper capacity? I read the piece in the pool school here - category/pool-school/pool_pump_basics - but I don't really see how to calculate the proper size for a specific application.


thanks again!

 

[duraleigh]

Is there a resource somewhere on this site to calculate the proper capacity? I read the piece in the pool school here - category/pool-school/pool_pump_basics - but I don't really see how to calculate the proper size for a specific application.

There's some real hydraulics experts on the forum that can get pretty precise but I can give you a decent ballpark figure.

Choose a pump (assuming single speed or the high part of a 2 speed) that will turn over your entire pool 2-3 times in a 24 hour period of continuous operation.....so, with a 14k pool you need to pump around 35k gallons in 24 hours (14 x 2.5). That works out to 25 gallons per minute.

Then you look at the pump curve on the manufacturers site and find out how many gallons/min the pump will produce given the systems "head" or resistance. The "head" is quite difficult to calculate and many people are happy to just use 40 - 50 as an approximate value.

To make a long story short, I think you'll find that even a 3/4HP pump will exceed the 25gpm you need and will be perfectly adequate for your pool.

 

[horn1993]

so the continuing saga of my motor problems...

I was able to crack it open and discover a batch of badly scortched (to the point of melted) wires around the main power connection (yes, i turned off the breaker).

Now I have a motor and pump I need to figure out what to do with.

1. I can't seem to disconnect the pump from the motor (can't see the set screws that connect to the shaft extension)

2. I need to find out what to do about the motor - either fix it or replace it. Any suggestions on places that could repair it in Plano / Dallas TX?

3. Is it possible to swap it if it can be repaired? I really think the 2 HP is too big and would be happy to work out a fair trade for a smaller one...

thanks again!

 

[spishex]

If you have a picture of the pump that would be a big help. The model information you listed in the original post was for the motor itself and not the actual wet end of the pump. If nothing else a part number off the lid or strainer basket would do the trick.

If you're capable of taking care of the scorched wiring in the back, the rest should be pretty easy once we get a diagram of your pump for you. If you want to change the motor size we'll have to know the part number of your impeller. It might already be a lower HP since your old service guy upped your motor HP. You can go up in HP and not worry about your impeller, but you have to be more careful when sizing down.

 

[New2Me]

I can't seem to disconnect the pump from the motor (can't see the set screws that connect to the shaft extension

You're gonna have to dis-assemble the pump to remove the impeller from the shaft, and then the motor from the pump.

 

[horn1993]

OK... my saga continues...

Here's the situation : I'm trying to pull the pump off the motor and I can't get them separated. I broke down the pump to just the impeller and the plate seal (attached to the motor -- and yes I unscrewed the 4 large bolts attaching the motor). I have pulled the end cap off the back of the motor and holding on the end of the shaft while trying to unscrew the rounded head screw that appears to go straight into the end of the shaft BUT I CANNOT GET IT UNSCREWED!!! :grrrr:

Any suggestions or tricks? am I doing this wrong?

Here are more details -
Motor: Century Centurion (apparently also called a Magnatek 1081???)
cat: B855 Part 7-177897-22
HP: 2.0 SF: 1.10
this one here: http://www.poolsmartpools.com/Detail.bok?no=190
Pump - apparently a pentair challenger based on the part number 35-5303 and this parts page : http://www.poolsupplybargains.com/catal ... Challenger

At this point I think I just want to toss this "scortched?" 2 hp motor and replace it with the 3/4 hp version here: http://www.poolsmartpools.com/Detail.bok?no=212 but I can't get the pump separated yet and don't really want to replace it too....

thanks again....

 

[Ohm_Boy]

The screw is probably a left-hand threaded screw. Try turning it clockwise.

 

[spishex]

Affirmative. The screw in the middle of the impeller is reverse threaded.

 

[horn1993]

Thanks for the confirmation here but I CAN NOT get this thing off... Any ideas? At this point I'm just planning to drill it out and assume a new motor comes with a new screw..... any thoughts on that?

I've got a wrench on the back of the shaft and it just won't come loose...

 

[horn1993]

thanks all for help on this. finally a few good whacks of the rubber mallet to the screwdriver while the motor was in the bench vice and it decided to give in...

Now just to recalc what size the motor should be and order it (and hopefully drop the electric bill this summer...)