Pump overheating: too much HP for pool?

[op999]

Hi all -- i just got a rebuilt 2 hp pump after the old one (1 hp) started buzzing. Seems to work OK at first but it gets very very hot after a few minutes of use. A few times it has auto shut down, and after a few minutes it would start back up.

I've checked the breakers (I changed the one inside the house to a 30, since there's 10 wire running to the outside), made sure the connections to the motor are snug (they are clips), made sure the wires are not touching, the ground wire is firmly attached, the filters and everything is clean. The plumbing is 1.5, and the pool, which includes a spill-over spa all running on the same pump, is about 22k-25K gallons (it's 16'x36'). Pump-pool distance/elevation is average. And I made sure to change the impeller to that of a 2 hp.

Could it be that I'm running too much HP power on the pool? What else could cause the pump to run hot? I just turned it on, and it ran for 30 minutes. But it was so hot as to water bubbled when I sprinkled the top of the motor case.

 

[vln]

Did you just replace the motor or the whole entire pump? You should NEVER use a more powerful motor on a less powerful pump assembly.

 

[op999]

Did you just replace the motor or the whole entire pump? You should NEVER use a more powerful motor on a less powerful pump assembly.

Kept the old pump (it's a Sta-rite Duraglas) but changed the empeller.

 

[vln]

That's why. Your using a much more powerful pump with an underpowered impeller.

I'm surprised you haven't burned out the pump/seals for good. I would either A, replace the pump housing or B, return the new pump.

Never mind I didn't read your changed the impeller. That's strange...

 

[Bama Rambler]

If you put a 2hp impeller on a 1hp motor it's no wonder it's running hot. You need to go back to a 1hp impeller designed to match that motor.

 

[Melt In The Sun]

Seems like there's a bit of confusion...you have a 2 hp motor running a 2 hp impeller, right? A 2 hp motor with a 1 hp impeller will not cause problems. A 1 hp motor with a 2 hp impeller will.

 

[op999]

Seems like there's a bit of confusion...you have a 2 hp motor running a 2 hp impeller, right? A 2 hp motor with a 1 hp impeller will not cause problems. A 1 hp motor with a 2 hp impeller will.

Correct: I have a 2 hp motor running with a 2 hp impeller.

The pump (a Sta-Rite Dyna-Glas/Dyna-Max -- not sure which one), as far as I can tell, is supposed to handle 2 hp. The diffuser, according to the part number (C1200PA) is good for up to 2.5 hp.

 

[vln]

You should try reading the voltage on the pump wires. Sounds like it may be overdrawing amps.

 

[op999]

You should try reading the voltage on the pump wires. Sounds like it may be overdrawing amps.

The max amps on the motor is 12.

I'm running 12-gauge wire from the motor to the timer/timer to breaker, where I have 20 amps. From there I'm running 10 wire to the house breaker, where I have 30 amp breaker.

 

[mas985]

You may have a full rated 2 HP impeller on an uprated 2 HP motor which would also cause a problem. What is the service factor on the motor and the part# for the impeller?

 

[op999]

You may have a full rated 2 HP impeller on an uprated 2 HP motor which would also cause a problem. What is the service factor on the motor and the part# for the impeller?

The SF, according to the label (the motor, an A.O. Smith, was rebuilt; not sure if to original specs) is 1.1.

Will have to take apart the pump tomorrow to see. I do remember the guy who sold me the motor installed another one, and I saw that the water channel (for lack of better term) was about 75 percent wider than the old one for 1 hp.

 

[4JawChuck]

Your "rebuilt" 2 HP motor likely has a shorted armature, thats why its overheating. Probably why it was discarded for a new one in the first place. You can check the armature for shorts using an armature "growler"...but I would just get my money back and get a new 1HP motor instead of some "rebuilt" one from this guy.

 

[mas985]

The SF, according to the label (the motor, an A.O. Smith, was rebuilt; not sure if to original specs) is 1.1.

Will have to take apart the pump tomorrow to see. I do remember the guy who sold me the motor installed another one, and I saw that the water channel (for lack of better term) was about 75 percent wider than the old one for 1 hp.

A SF of 1.1 is an uprated motor so you should be using a full rated 1.5 HP impeller. But if the impeller is sized for a full rated 2 HP motor, then it will likely cause the motor to overheat.

If the impeller is sized correctly then it probably is the motor itself and should be the installer who replace it. Is there a reason you upsized the pump in the process?

 

[op999]

The SF, according to the label (the motor, an A.O. Smith, was rebuilt; not sure if to original specs) is 1.1.

Will have to take apart the pump tomorrow to see. I do remember the guy who sold me the motor installed another one, and I saw that the water channel (for lack of better term) was about 75 percent wider than the old one for 1 hp.

A SF of 1.1 is an uprated motor so you should be using a full rated 1.5 HP impeller. But if the impeller is sized for a full rated 2 HP motor, then it will likely cause the motor to overheat.

If the impeller is sized correctly then it probably is the motor itself and should be the installer who replace it. Is there a reason you upsized the pump in the process?

I believe the impeller is for a 2, so that may be it.

But, giving it more consideration, I may go back to a 1.5 motor. (The man who I bought the pump from has 1.5 as well). I bought the 2 thinking that, since it's a larger pool with a spill-over spa, it would work better. He said he'd work with me and we can trade down.

But now I am stuck with a 2 hp impeller. Will that works for a 1.5 hp motor?

 

[Bama Rambler]

But now I am stuck with a 2 hp impeller. Will that works for a 1.5 hp motor?

No, Your problem now is that your impeller is too much for your motor. If you go to a 1½hp motor you'll have to know the SFHP (service factor horse power) in order to get the correct impeller to match it.

 

[op999]

But now I am stuck with a 2 hp impeller. Will that works for a 1.5 hp motor?

No, Your problem now is that your impeller is too much for your motor. If you go to a 1½hp motor you'll have to know the SFHP (service factor horse power) in order to get the correct impeller to match it.

Well what's a good range so I can figure out what impeller I will need?

(He has a variety of motors; last time he just gave me one, but I think he'll let me me pick my own, now that the impeller has come into play.)

 

[mas985]

You really don't need much HP for your size pool. I have a 1/2 HP pump for a 20k pool so unless you need a lot of flow rate for something else, spa jets or water features, I would downsize both the impeller and motor. Just make sure they are a matched set. Do you still have the 1 HP impeller or is that from a different pump all together?

 

[op999]

You really don't need much HP for your size pool. I have a 1/2 HP pump for a 20k pool so unless you need a lot of flow rate for something else, spa jets or water features, I would downsize both the impeller and motor. Just make sure they are a matched set. Do you still have the 1 HP impeller or is that from a different pump all together?

Well I was thinking that, since the average starting pool is about 15K, and mine's 25K (with a spillover spa), it would work. With 1 HP, the spa didn't push out much water.

At first I was thinking a 2 HP would work fine, but I'm starting to see otherwise.

As for the impeller, the old 1 HP one was shot (overheated a few times perhaps and was damaged), so I bought a second-hand one for a 2 HP.

 

[mas985]

Are you using the same pump for the spa jets? If so, then a two speed 2 HP might be the solution. You have high speed for the jets and low speed for the pool.

If you have a separate pump for the jets, then the pool pump is just needed for circulation. If you want a dramatic spa overflow, then you might need more flow rate but that will be at the expense of energy consumption. Plus you really don't get that much more flow rate (~20%) out of a 2 HP than a 1 HP but the energy consumption is a lot more.

 

[op999]

Are you using the same pump for the spa jets? If so, then a two speed 2 HP might be the solution. You have high speed for the jets and low speed for the pool.

If you have a separate pump for the jets, then the pool pump is just needed for circulation. If you want a dramatic spa overflow, then you might need more flow rate but that will be at the expense of energy consumption. Plus you really don't get that much more flow rate (~20%) out of a 2 HP than a 1 HP but the energy consumption is a lot more.

Yes I am running the same pump for both.

However, I've never been a fan of that spa. It doesn't have a heater, and even if it did, it's harder (and more costly) to keep warm than an external/normal hot tub. Not that I use it much (if ever), but it seems to get dirtier more than the pool. So my guess was a higher HP motor to circulate water better.

I think I am now deciding on whether to go to 1.5, or just go back to a 1 hp. Does a 1 vs. 1.5 make a big difference?