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Pump Motors Keep Burning Out?


nickanat

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After being about to replace our 3rd pool pump motor, I thought I'd ask and see if anyone has any ideas why they keep burning out.

The first motor went after about a year and a half (we swim most of the year, and the pump runs on average 4 hours a day, all year round), and we found out we had a small air leak that was causing it to start dry every day, probably causing the seals inside the motor to overheat and break allowing water to flow in and damage it. We fixed the leak and bought a new motor.

The second motor was working fine for about the same amount of time before it too stopped working. When we had it bench tested it showed positive for water damage. So we bought another motor and and built a well ventilated covering for it to keep it away from rain.

The third motor went after about a year and a half again, because of water damage due to a broken seal. Any ideas what could be causing it this time? The system was staying primed and the motor was out of the rain, but it somehow managed to get water damage and burn out again.

The motors have all been 2HP, rated for and running single-phase @ 240volts. Our climate is realtively warm so water temperatures never drop below 50ish degrees F.

Please help

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What were the brand/model of the pumps?

We went through 3 so far, I remember the first being Hayward branded, the second I cant remember, and the third is Marathon Electric. They were all physically similar, and all of the important areas matched up they way they should have.

Would running the pump without water for a few seconds until it primed be enough to damage it? On all the motors, I ran them a few times without water in it for one reason or another until it self-primed, although after that it always had water in it upon starting.

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No, most pumps today are self-priming. You can run them dry for a minute plus without worry, although that's not recommended. If they lie in the sun all day that can be a factor - heat kills the pump, whether it's due to running dry or from extended exposure to the sun. Even then, they should last alot longer than 12-18 months. Something's not right. Do you test your own water or take it elsewhere? Also, you may have an electrical problem. Strange.

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No, most pumps today are self-priming. You can run them dry for a minute plus without worry, although that's not recommended. If they lie in the sun all day that can be a factor - heat kills the pump, whether it's due to running dry or from extended exposure to the sun. Even then, they should last alot longer than 12-18 months. Something's not right. Do you test your own water or take it elsewhere? Also, you may have an electrical problem. Strange.

Well I thought it was an electrical problem this 3rd time especially, since the motor would hum with the switch set for 110 voltage instead of 220, but it would draw too much from the breaker and trip it. Using a voltmeter I was able to check and see that we are in fact getting almost exactly 240 volts @ the leads connecting to the motor (which it is rated for). I normally check the water myself but sometimes bring it to a local pinch a penny, and I keep it well maintained. The filters are cleaned out every 3 months and the chlorine cell is checked and cleaned in diluted muriatic acid as well. This has me stumped.

Can you get a voltage and current (amperage) reading at the pump with the pump running?

How hot is the motor? Is it causing the paint or label to discolor?

What is your system pressure?

Has the motor ever been flooded?

The voltage is 240, but since nothing happens set to 220, when testing it at 110, it has to be drawing more than 20 amps because the breaker trips at 20. All motors would run relatively warm, but not too hot to touch, and only the first motor showed paint damage, but then again that one was in direct rain. The system pressure when running is within the specs of a small pressure gauge on my filter and on the distributor for the in floor cleaner, my guess is somewhere around 30psi? I'm probably wrong as I havent looked at it in a while. The motors have never been submerged in water. Only the first and second motors were submitted to rain.

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No, most pumps today are self-priming. You can run them dry for a minute plus without worry, although that's not recommended. If they lie in the sun all day that can be a factor - heat kills the pump, whether it's due to running dry or from extended exposure to the sun. Even then, they should last alot longer than 12-18 months. Something's not right. Do you test your own water or take it elsewhere? Also, you may have an electrical problem. Strange.

Well I thought it was an electrical problem this 3rd time especially, since the motor would hum with the switch set for 110 voltage instead of 220, but it would draw too much from the breaker and trip it. Using a voltmeter I was able to check and see that we are in fact getting almost exactly 240 volts @ the leads connecting to the motor (which it is rated for). I normally check the water myself but sometimes bring it to a local pinch a penny, and I keep it well maintained. The filters are cleaned out every 3 months and the chlorine cell is checked and cleaned in diluted muriatic acid as well. This has me stumped.

Can you get a voltage and current (amperage) reading at the pump with the pump running?

How hot is the motor? Is it causing the paint or label to discolor?

What is your system pressure?

Has the motor ever been flooded?

The voltage is 240, but since nothing happens set to 220, when testing it at 110, it has to be drawing more than 20 amps because the breaker trips at 20. All motors would run relatively warm, but not too hot to touch, and only the first motor showed paint damage, but then again that one was in direct rain. The system pressure when running is within the specs of a small pressure gauge on my filter and on the distributor for the in floor cleaner, my guess is somewhere around 30psi? I'm probably wrong as I havent looked at it in a while. The motors have never been submerged in water. Only the first and second motors were submitted to rain.

Is there an open air space under the motor for ventilation? No mulch, stone etc. Are you sure the impeller horsepower rating is not to much for the pump motor

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30 psi indicates that the pump is way too big for your system. Usually, the pressure should not exceed 22 psi. What brand of in-floor cleaner do you have? Is it Caretaker? Pool Valet?

For Caretaker, the normal operating pressure is between 14-20 PSI.

You could reduce your impeller to a 1.5 HP. That would reduce your pressure. For some models of pump, when you change the impeller, you also have to change the diffuser.

What suction and return lines do you have? Number and diameter?

When you checked the voltage to the pump, did you check the voltage at the terminals while the pump was running or while the pump was off? It would help if you could get a voltage at the pump while the pump is running and also a current in amps.

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Normally, water would cause the pump to trip the circuit breaker before it would cause damage to the motor. I have yet to see water damage a pump to the point of causing failure 3 consecutive times. Most failures are due to overheating.

When you say the pump motors fail, how do you mean they fail? Do they simply fail to start with no noise, do they hum and sound like they are trying to work? or do they suddenly stop while in operation? Does the motor have a burnt smell or is there any indication of water leaking from around the shaft seal where the motor meets the pump?

What I do see on occasion are burnt wires at the pump motor where the power lead connects to the motor. The connectors overheat and fail, but this is easily repaired and does not require the replacement of the motor.

I would agree that the 2 hp pump is too much for that system. usually the pressure should be around 10-15 psi, and not over 20 on a consistent basis.

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Is there an open air space under the motor for ventilation? No mulch, stone etc. Are you sure the impeller horsepower rating is not to much for the pump motor

The pool company gave us our pump and motor together. The motor it came with was 2 HP. All of the motors have been well ventilated.

30 psi indicates that the pump is way too big for your system. Usually, the pressure should not exceed 22 psi. What brand of in-floor cleaner do you have? Is it Caretaker? Pool Valet?

For Caretaker, the normal operating pressure is between 14-20 PSI.

You could reduce your impeller to a 1.5 HP. That would reduce your pressure. For some models of pump, when you change the impeller, you also have to change the diffuser.

What suction and return lines do you have? Number and diameter?

When you checked the voltage to the pump, did you check the voltage at the terminals while the pump was running or while the pump was off? It would help if you could get a voltage at the pump while the pump is running and also a current in amps.

Well, I cant get a reading without a motor, but when the last one stopped working when i tested it on at the terminals it was 240volts but was not doing anything, no blown breaker and no noise or movement.

The suction and return appears to be 2 or 2 1/4. The filter is a larger canister filter with 4 canisters in it. I cant check the model of infloor cleaner, but caretaker sounds right. Also, the psi readings I posted were guesses from what I remember seeing the last time I checked it, so dont hold me to them.

Normally, water would cause the pump to trip the circuit breaker before it would cause damage to the motor. I have yet to see water damage a pump to the point of causing failure 3 consecutive times. Most failures are due to overheating.

When you say the pump motors fail, how do you mean they fail? Do they simply fail to start with no noise, do they hum and sound like they are trying to work? or do they suddenly stop while in operation? Does the motor have a burnt smell or is there any indication of water leaking from around the shaft seal where the motor meets the pump?

What I do see on occasion are burnt wires at the pump motor where the power lead connects to the motor. The connectors overheat and fail, but this is easily repaired and does not require the replacement of the motor.

I would agree that the 2 hp pump is too much for that system. usually the pressure should be around 10-15 psi, and not over 20 on a consistent basis.

Well, the first two motors would fail in that they would trip the breaker while making loud humming noises. This most recent one only tripped the breaker once, but after messing around with it for a while it would make no noise set at 230, and not trip the breaker. Set at 115 *by the way of a switch on an access plate on the back of the motor), it would hum and within 10 seconds or so it would trip the breaker.

I cant remember them having any burnt smell and there is no indication of water leaking. Both pinch a pennys have told me that the seals failed and water got into the motor housing/windings.

I plan on spending the money to fix it again within 2 weeks, but I would hate to go through another motor in a year. My filter I believe is a Hayward Swimclear with the 4 canisters inside it. My pool is around 15-16k gals, with 3 returns, 2 spa jets, a 36inch waterfall, and roughly 20 cleaning heads, but I only have one or two of them running at the same time. Should I just buy a whole new pump and motor? With a new motor costing around 250-350, my budget isn't much higher than that. I really appreciate all the help, thank you.

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Well I went and took a look at the psi gauges and on the filter there is an adjustable knob with with two needles, one green and one red, 5 psi after it to remind you when to clean the filters. The green needle was last set on around 25 psi. Also, looking at the psi gauge on the device that distributes water for the in-floor cleaner I can remember seeing it bounce around 20-30 psi.

Also, before buying a new motor, I intend to take the old one apart and look for anything easily repairable. Is there anything in specific that you would recommend? Also, when going to buy a replacement motor would you suggest 1.5 HP as a good replacement considering the psi may be too high using 2 hp motors? Thank you again.

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Well I went and took a look at the psi gauges and on the filter there is an adjustable knob with with two needles, one green and one red, 5 psi after it to remind you when to clean the filters. The green needle was last set on around 25 psi. Also, looking at the psi gauge on the device that distributes water for the in-floor cleaner I can remember seeing it bounce around 20-30 psi.

Also, before buying a new motor, I intend to take the old one apart and look for anything easily repairable. Is there anything in specific that you would recommend? Also, when going to buy a replacement motor would you suggest 1.5 HP as a good replacement considering the psi may be too high using 2 hp motors? Thank you again.

I believe the following was already suggested earlier in this thread.

If you want to get a smaller Hp motor, that is fine, But you MUST also get an impeller that is the same as the motor (Hp) that you are getting. On some pumps, this requires that you also replace the diffuser as well. I would take your present impeller to your pool store and have them run the numbers to tell what size it is (Hp). Running a 1 Hp motor with a 2 Hp impeller will kill the motor, too much load on it.

Something else to consider is solar. I did not recall if you said if you had solar or not. Be very careful of Hp selection as you may need more flow to feed the panels. This may be why you have a 2 Hp pump to start with. If these motors never had loud growling sounds before they died, I would lean more towards the sunlight / cooling air theory's

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Okay what is happening is the salt water is corroding the seal pretty fast. This is something that I have experienced with my salt water pool customers as well. I have talked to my distributor about the issue and they informed me that they believe A.O. Smith is working on fixing the problem. Once that seal corrodes that salt water is shooting directly into the motor killing it faster than normal chlorine water. Don't get me wrong i love salt systems I think they are great, but this is one of those things that is a downside. What I would suggest if you are getting about 1 1/2 years out of one motor you may want to have the seal changed out, which is easy to do, maybe every 8 months. I know that sounds like a pain but a seal is around 15-25 dollars and it is a lot cheaper than a motor. Hopefully one of the motor manufacturers will come out with something soon to help with this problem. I've had to warranty 3 pumps this year due to that reason (they all failed within a year).

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Okay what is happening is the salt water is corroding the seal pretty fast. This is something that I have experienced with my salt water pool customers as well. I have talked to my distributor about the issue and they informed me that they believe A.O. Smith is working on fixing the problem. Once that seal corrodes that salt water is shooting directly into the motor killing it faster than normal chlorine water. Don't get me wrong i love salt systems I think they are great, but this is one of those things that is a downside. What I would suggest if you are getting about 1 1/2 years out of one motor you may want to have the seal changed out, which is easy to do, maybe every 8 months. I know that sounds like a pain but a seal is around 15-25 dollars and it is a lot cheaper than a motor. Hopefully one of the motor manufacturers will come out with something soon to help with this problem. I've had to warranty 3 pumps this year due to that reason (they all failed within a year).

That is wierd AO smith does not make seals. A Viton pump seal should be able to withstand harsh enviroments. That what the O rings are made from for chlorinators. I have never had to replace seal because of a salt system. How did you determine it was the salt? Poor water chemistry can eat a seal in no time.

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Salt is not damaging anyone's seal. Salt has nothing to do with this. If the seal does start to leak, water will not go into the motor unless the leak is very bad. The pump is designed to allow water from a leaking seal to get out without getting to the motor. A seal that starts to leak will be indicated by a drip from under the pump.

The OP does note a broken seal, so that could have allowed water to get into the motor, but it would have had to be a big leak. There is no need to replace a pump seal unless it is leaking. Seals are usually very reliable and they are designed to withstand harsh environments.

I have noticed that new pump motors have been running hot lately.

I think that motor manufacturers are probably trying to save money by reducing the quality of the motors. I think that they are probably using less copper in the windings due to the recent price increases of raw materials.

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Well I just took apart the motor and besides a dried up moth and some shoddy windings there wasn't much I could find wrong with it except that the center part of the shaft that is inside of the motor that the magnets were mounted on was very rusted. The outer ends must be stainless because they looked fine. Both bearings seemed to be in decent condition and all the wiring was intact as far as I could tell.

The outer plate of the motor that meets up with the pump did have some minor corrosion and alot of salt residue on it, however, I did not see any signs of salt inside the motor as I expected to see. Could high temperatures/poor thermal protection (there was no sensor on it that I could see) do that sort of damage? About a day before it stopped working I went to check the salt level and there was no dripping water coming from anywhere. There never has been with this motor.

I'm about ready to give up on it and see if I cant get a few bucks for the copper windings.

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Another thing to consider is that when sizing a new motor you have to calculate the "Total Horsepower" of the motor. The Total Horsepower of the new motor has to be equal to or greater than the Total Horsepower of the old motor. Ideally, you want the exact same total H.P for maximum efficiency.

For example, if the old motor was rated at 2.0 H.P with a Service factor of 1.32, then the total horsepower is 2.64. If you use a motor rated at 2.0 H.P with a service factor of 1.0, then your motor is way too small. If you don't know the service factor of the old motor, then you need to assume that it was about 1.32 to be safe, and if the new motor has a service factor of less than 1.32, then you should change the impeller to a 1.5 H.P to avoid overheating your motor.

Another example: If you have a 1.5 H.P motor with a Service factor of 1.0, you can replace it with a 1.0 H.P motor that has a service factor of 1.5; they are the exact same motor.

Also, note this from California Title 20 for those of you who live in California.

1. Pump Motors. Pool pump motors with a capacity of 1 HP or more which are manufactured on or after January 1, 2008, shall have the capability of operating at two or more speeds with a low speed having a rotation rate that is no more than one-half of the motor's maximum rotation rate.

http://www.energy.ca.gov/siting/title20/index.html

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Thank you everyone for your help. I decided on a 1.5 HP motor with a service factor of 1.47 from a local Leslies Pool and Spa. They have a complete one year warranty, that even covers water damage. The motor is made by Emerson Motors, and the build quality seems to be somewhat better. I also noticed it was substantially heaver, which I hope equates to much tighter windings.

However, I think I found the problem that most likely killed all three of my motors. It turns out that the "distributor" for the infloor cleaning system had its own little strainer basket, which I only found out about by accident while reading about pool pumps online. When I removed the section of pipe and took out the strainer, easily 70% of it was covered in hair amongst other things. It had never been cleaned in almost 5 years of running, so I'm guessing the increasing strain on the motor killed it faster.

Speaking of strains, my system pressure is now around 4psi, but I expect that to rise as the filter fills with algae until i clean it tomorrow. I also decided to drain out some of the water because about a year ago when I had the water tested the Parts-per-million was very high and the tester at pinch-a-penny advised that I empty a portion of the pool and refill it.

If anyone has any other advice, I would appreciate it. Thank you again for all your input, it really helped me make a decision that I think is going to be a good one for the next several years to come.

Another thing to consider is that when sizing a new motor you have to calculate the "Total Horsepower" of the motor. The Total Horsepower of the new motor has to be equal to or greater than the Total Horsepower of the old motor. Ideally, you want the exact same total H.P for maximum efficiency.

For example, if the old motor was rated at 2.0 H.P with a Service factor of 1.32, then the total horsepower is 2.64. If you use a motor rated at 2.0 H.P with a service factor of 1.0, then your motor is way too small. If you don't know the service factor of the old motor, then you need to assume that it was about 1.32 to be safe, and if the new motor has a service factor of less than 1.32, then you should change the impeller to a 1.5 H.P to avoid overheating your motor.

Another example: If you have a 1.5 H.P motor with a Service factor of 1.0, you can replace it with a 1.0 H.P motor that has a service factor of 1.5; they are the exact same motor.

Also, note this from California Title 20 for those of you who live in California.

1. Pump Motors. Pool pump motors with a capacity of 1 HP or more which are manufactured on or after January 1, 2008, shall have the capability of operating at two or more speeds with a low speed having a rotation rate that is no more than one-half of the motor's maximum rotation rate.

http://www.energy.ca.gov/siting/title20/index.html

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You should have your water retested before draining based on year old numbers. You should get the Taylor K-2006 test kit so that you can test your own water. I'm glad that you found that in-line strainer; I should have thought to tell you to check that.

4 psi seems a little low for your filter pressure.

01) Can you get a voltage reading at the pump terminals while the pump is running?

02) Is the cleaner system working properly?

03) Are there two returns, one for the cleaner and one for the wall?

04) Does the pump seem to be working OK?

05) Did you replace the whole pump or just the motor?

06) If you just replaced the motor, did you replace the impeller as well?

07) If you replaced the impeller, what size impeller did you use?

You could have a bad pressure gauge; does it seem to be working OK

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The voltage at the pump motor was 238 when I tested it yesterday after installing, and while the cleaning system is not working perfectly, it is because the cleaning heads and the small plastic "teeth" that control the rotation of the head are worn down. They do pop up completely and drop down completely (for the most part). The one that was recently replaced (polaris gave us an extra head to use when you send in the defective one) works exactly as is should. The waterfall flow is much better than anything I remember, even when the pool was new.

There are 2 drains, and both return on one single pipe, while the skimmer returns on another.

The pump does seem to be working fine, no bubbles or other issues other than when it was first started. I did use a garden hose to force some water into the pump before running is as a safeguard.

We replaced the motor and impeller, as well as a couple of seals and gaskets. The impeller appears to be exactly the same size as the old one.

Both the pressure gauge on the filter and on the infloor cleaning distributor read anywhere from 4-6. I will double check them when I clean the filters in a little while.

I did drain the pool about a third of the way down, almost so the water was about 18 inches from the waterline.

You should have your water retested before draining based on year old numbers. You should get the Taylor K-2006 test kit so that you can test your own water. I'm glad that you found that in-line strainer; I should have thought to tell you to check that.

4 psi seems a little low for your filter pressure.

01) Can you get a voltage reading at the pump terminals while the pump is running?

02) Is the cleaner system working properly?

03) Are there two returns, one for the cleaner and one for the wall?

04) Does the pump seem to be working OK?

05) Did you replace the whole pump or just the motor?

06) If you just replaced the motor, did you replace the impeller as well?

07) If you replaced the impeller, what size impeller did you use?

You could have a bad pressure gauge; does it seem to be working OK

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