Seized Pump Motor should I also replace diffuser?

[AggieMoose]

Pac Fab Challenger 1.5 hp pump with a US Motors EB842 replacement motor installed some time before I had the pool (moved in 5 days ago, Murphy's Law in full effect). Noticed the pool wasn't running when it was supposed to, went over to the equipment pad, and smelled the sweet aroma of a burned up electric motor. Tried to start it up and got nothing but a click and more wafts of sweet electrical burning, so I cut off the power at the breaker. Disassembled the pump and looked for obstructions, nothing. Tested the capacitor with my multimeter, it was fine. Tried to spin the motor, and it is seized. I'm guessing its toast.

So, time to replace the motor. First question is whether anyone has suggestions for a good reliable and efficient motor for this pump? Should I just go with another like the one that failed, or a different one?

Second question is how to go about the rebuild, because I've never done this before although I'm fairly handy. I already figure on getting a full replacement gasket set that includes the ceramic pump seal part. The big issue is whether I ought to replace the diffuser and/or the impeller as well. When inspecting the rest of the internals I noticed that the brass ring inside the diffuser is pretty chewed up. So I'm thinking I ought to replace that piece as well? The impeller part that it interfaces with also looks kind of scratched up, but not in too bad of shape. But should I go ahead and replace it as well just for safe measure? See pic of diffuser below sorry for the low quality I took those with my phone.

If I were a betting man, I'd bet that this chewed up brass ring had something to do with the motor burning up too. Which is weird because it wasn't making too much noise or anything. Thanks in advance for the help folks, this is my first pool so I'm a total novice at this stuff.

 

[WASP]

If that is the suction port I'm seeing then That ring is commonly referred to as the "wear ring". If this pump has an enclosed impeller there will be a mating ring on it. The clearance, gap, between the two rings form an annulus which restricts internal recirculation from the discharge to the suction side of the pump. This recirculation is wasted hydraulic power. The smaller the clearance, the more efficient the pump will be.

You may be money ahead just replacing the entire pump/motor assembly.

 

[AggieMoose]

Yes, exactly what I was trying to determine. There's no mating ring that I can see on the impeller it just sits inside that wear ring and as it stands, it fits pretty loose. I was just thinking that it seemed inefficient but I'm no engineer.

Pricing out a new motor, diffuser, impeller, and gasket/seal set, and I'm only a couple hundred away from a whole new pump of equivalent manufacture. The rest of the pump seems in perfectly fine shape though. But definitely worth considering. At some point in the next couple years I'd like to upgrade the whole equipment pad, but for now that's on the "nice to have" list since we just moved in and I have a dozen other more pressing projects. Ah, the joys of homeownership!

 

[pooldv]

Congrats on the fried pump! Definitely get at least a 2 speed pump, same size. Running on low will cut your electric bill to 25%. A 2 speed pump moves half the water for 25% of the electric cost on low speed. Low speed is plenty for most filtering and circulation. Or take a look at the Superflo, 342001.

Pentair SuperFlo VS Pump 342001 | Pentair 342001

 

[AggieMoose]

I'm definitely looking into a 2 speed pump now that I'm pricing stuff out. I guess I could figure this out myself, but will the SuperFlo fit into the same plumbing rough-in as the Challenger that I have? Not that I'm too lazy to replumb or anything, just looking for "easier" at this point

 

[AggieMoose]

Here's a wrinkle. From my research I've discovered that the original motor on the pump was a 1.5 hp motor with SF of 1.10, giving a SFHP of 1.65. This is according to the specs on Pentair's website. The replacement motor that is now a lump of toast was a US Motors Emerson EB842 which is a 1.5 hp with SF of 1.47, giving a SFHP of 2.20. So it seems like whoever replaced the original motor with the one that just burned up oversized the motor for the pump. Could this have been a factor in the motor have burning up? Could this have other adverse effects like poorer filtration or too much pressure in the pipes?

So...assuming I don't replace the whole thing with a new two-speed or variable speed pump, should I source a replacement motor that gives a SFHP closer to the original 1.65. The Emerson EB841 looks to fit that bill at a rating of 1 hp with a SF of 1.65 giving SFHP of 1.65. It's also a lot cheaper than the bigger motor.

 

[WASP]

Both motors will turn at 3600 RPM so the pump will perform the same. Now if you had a smaller HP motor trying to spin the pump 3600 RPM, the motor would draw to much current and trip the breaker or burn itself up.

Two speed pump is what I would do. Rebuilding your old pump is just putting lipstick on a pig.

 

[pooldv]

I don't know if the pump is plug and play or requires a replumb. It is important to match the impeller to the motor. As long as whoever replaced the motor replaced the impeller it would be ok. If they didn't then it could create problems. Be sure to order a matching impeller for the motor you decide on.

 

[AggieMoose]

I thought of that earlier and checked: prior repair did not match the impeller. The part number of the old impeller is original to the pump model with SFHP of 1.65. I decided to go ahead and rebuild the pump and source a motor appropriately sized to a new impeller. Ordered new seals and diffuser as well, got it all for a couple hundred bucks online. Thought seriously about upgrading to a VS pump but this is a cheapo solution to tide me over for a while until I redesign the entire equipment pad in the next 2-3 years. Electricity is very cheap where I live so calculating my cost per kwh it didn't make much sense to upgrade just yet.

When the parts get here I'll update the thread to document the repairs, hopefully with pics.

 

[pooldv]

Good plan!

 

[AggieMoose]

Just by way of update, I was able to successfully replace the pump motor, diffuser, impeller, and seals successfully! I didn't take pictures of the repair because it was cold and raining and I wanted to work quick, but if anyone reading this has a challenger pump, there are quite a few good YouTube videos out there showing the process. Thanks for the help everyone!