My second burned out pump

[jongig]

I had a Hayward Max-Flo 2 - 2 speed 1 HP 230 volt pump go bad in August and the replacement just went today. I installed a roof solar system and I'm wondering if I'm not using enough HP. I don't have a vacuum relief valve in the solar and I didn't notice more than about a 2 PSI difference between the solar system on and off.

The pump motor looks burned. My flow has been fine and I would think the motor has thermal protection if it got too warm. I've put my hand on the pump while running and It's hot but I don't have to remove my hand right away.

The distance to the top of the roof solar is maybe 12 feet but again the water does not drain out and so it pumps anmd down at the same time. I'm using 2 inch pipe throughout.

Should mention that the PSI at the filter is 16 PSI while running solar and about 14-15 PSI when just connected to the filter.

 

[Melt In The Sun]

12' is not too much of a height difference, and the height is only taken into account when priming anyway (pump pushes up, gravity pulls water down). I don't see how that could break a pump. What is the normal filter pressure?

 

[jongig]

12' is not too much of a height difference, and the height is only taken into account when priming anyway (pump pushes up, gravity pulls water down). I don't see how that could break a pump. What is the normal filter pressure?

I just realized I didn't post pressure so I edited my post to include the pressure between 14 and 16 PSI.

 

[JamesW]

The Max-Flo II is a medium head pump, so it's not the best choice for solar, but it should be fine as long as the total head loss is not too great. The top reasons that I can think of would be:

1) Voltage supply out of range.
2) Excessive suction head loss due to restriction, such as clogs etc..
3) Oversized impeller causing motor overload.
4) Impeller binding.

 

[jongig]

The Max-Flo II is a medium head pump, so it's not the best choice for solar, but it should be fine as long as the total head loss is not too great. The top reasons that I can think of would be:

1) Voltage supply out of range.
2) Excessive suction head loss due to restriction, such as clogs etc..
3) Oversized impeller causing motor overload.
4) Impeller binding.

The pump should be under warranty unless I did something wrong and I don't see that I did.

1. Voltage is about 248 volts. Pump is rated for 230 and 10% variance so I'm close.
2. suction line is long, nearly 50 feet and we ran 2 inch single line poly pipe to the aquagenie skimmer. Piping throughout is 2 inch except when it leaves the pad it goes to 1.5 inch poly pipe 50 feet back to the skimmer. The pump is about 3 inches above pool level and primes very easily. The solar system to the top is actually 16 feet above the pool and it is always filled with water but even when dry it fills quickly and easily in about 1 minute. The pump maintains prime all the time.
3. I've not changed the impeller and there is nothing in any skimmer.
4.When I removed the last pump I took it apart and it was clean.

Knowing pumps a bit. This pump has a insulation factor B which is a fairly high temperature, about 260 f.
I never measured amps and can't now but if the pump is restricted whouldn't it run cooler not hotter?
What is a high PSI for a pool pump?
I had plenty of flow and that's all I cared about.

I didn't remove this pump just in case someone wants to see that it has a prime. The pump basket is still filled to the top with water and primed.

The pool company is not going to be happy with this and the last time they gave me a hard time because I removed the pump.

 

[JamesW]

The SP2707X102, which is the two speed Max-Flo II 1.0 H.P with a service factor of 1.25 for a total H.P of 1.25, should not exceed about 50 feet of head for the total head loss from the suction and the return.

If we assume 37 feet of head for the return (16 psi) and 13 feet for the suction (5.6 psi), then that's about 50 feet total, which is at the top of the acceptable range.

Was the voltage measured while the pump was operating? Sometimes voltage is fine with no load but drops under load.

How long did the last pump last before burning out?

Getting measurements of the suction pressure, and the voltage and amperage under load would help.

You could have the motor evaluated at a local electric motor repair shop or you could run a few tests on the motor to see what might be wrong.

 

[jongig]

The SP2707X102, which is the two speed Max-Flo II 1.0 H.P with a service factor of 1.25 for a total H.P of 1.25, should not exceed about 50 feet of head for the total head loss from the suction and the return.

If we assume 37 feet of head for the return (16 psi) and 13 feet for the suction (5.6 psi), then that's about 50 feet total, which is at the top of the acceptable range.

Was the voltage measured while the pump was operating? Sometimes voltage is fine with no load but drops under load.

How long did the last pump last before burning out?

Getting measurements of the suction pressure, and the voltage and amperage under load would help.

You could have the motor evaluated at a local electric motor repair shop or you could run a few tests on the motor to see what might be wrong.

I'm not sure about your head loss calculations. At 25 GPM the poly pipe is in total to and from the pool less than 2 PSI in pressure drop. For the plumbing at the pad and to the roof and back was all done with the thought of head loss. My only pressure reading in the system is at the filter but the filter and it doesn't exceed 16 PSI.

Voltage in the house is data logged on the main lines. I wish I had measured the pump while running but I never noticed anything wrong. I've gone and touched the pump while running and I've never noticed it being too hot.

 

[JamesW]

I'm just guessing on the suction head loss. The only way to be sure is measure it. The return is based on the filter pressure. If we assume 7 feet of head loss on the suction, that puts us at 44 feet total, which equals about 48 gpm based on the head curve.

It could just be a bad motor. If the last one went prematurely, then there could be something wrong with the setup. Here are some measurements that could help diagnose system problems.

1) Flow rate (using a flow meter)
2) Voltage (under load).
3) Amperage
4) Suction pressure using a vacuum gauge.

Multimeter should be "true RMS".

You could have the motor evaluated at a local electric motor repair shop, or you could do it if you feel comfortable doing such things.

http://www.aosmithmotors.com/AboutUs/de ... spx?id=841

http://www.aosmithmotors.com/WorkArea/l ... &libID=609

http://www.hayward-pool.com/prd/In-Grou ... 002__I.htm

http://www.youtube.com/watch?v=mxbw-gE-Jww

http://www.youtube.com/watch?v=XUdRW0XgYQs

 

[jongig]

I appreciate the help and reading the AO Smith information was helpful. The pump is a 2 speed and the high speed is only used at startup for a few minutes and when the solar is on. I have a Pentair IC-40 salt cell and even on low speed the salt cell still gets enough flow. Flow requirement of the Pentair salt cell is 25 GPM.

The pump is just about flooded suction and if the inlet was the level of the pump shaft it would be flooded suction. At the time it burned up there was one leaf in the leaf basket in the pool.

I do have Fluke Trus RMS equipment but I never checked after the last failure. Not sure what the data logger uses but it matches my Fluke.

The picture attached is the voltage at the house on the afternoon the pump failed. It shows date, time, voltage min and voltage max for that 20 minute period. The pump failed at about 15:00.

I noticed a device that can be installed on pool pumps called a eMod, sounds like a good idea.

 

[duraleigh]

We need someone other than me to comment on this but that voltage seems unusually high.

Are you in the US?

Isn't most US single-phase residential voltage around 208-220. I don't even know if voltage that high would damage the pump but that 250v number jumps out at me.

 

[JamesW]

Service entrance voltage should not exceed 254 volts as a maximum (depending on the source of information), and 252 volts is considered high, but acceptable. The voltage seems to be running at, or slightly above, high on a regular basis.

The eMod shuts off power to the pump at any voltage over 250 volts as AO Smith considers this outside the acceptable range for the motor. 253 volts is 110 % of the 230 volts that the motor nameplate indicates, which is generally considered the acceptable range for that motor.

I'm not sure if overvoltage is a factor in the early failure of the motor, or not. It probably would shorten the life, but by how much is uncertain. Perhaps a call to the power company is in order to keep the power supply within the acceptable range.

Here are a few more things you can check:

1) Turn the shaft by hand to see how easily it spins. You can do this from the back by removing the small circular shaft cover.

2) Motor fan. Look in the front vents and turn the shaft to inspect the entire fan.

3) Verify voltage at the pump supply, not just at the house main service entrance.

4) Verify that the pump is wired correctly according to the wiring diagram on the side of the motor.

5) Check the capacitor.

6) Check winding continuity.

7) Check motor components for continuity to ground.

What is the filter pressure reading when the pump is on low speed?

Are you using any sort of alternate power supply such as solar or wind?

Another possibility is that the pump was left on low speed while the system was set to solar. Low speed might not have the ability to move much, or any, water up 16 feet. It's possible that the water just kept churning in the pump, which would cause the water to get very hot and overheat the motor. In that case, the inlet and outlet fitting to the pump would likely shrink and become loose unless they are schedule 80 CPVC.

http://www.spgs-ground.com/information/ ... age-ranges

 

[jongig]

Nice post James...

Just an update and then I’ll answer some of your questions. Pool Company came out and took the wires off the pump and with a multimeter measured 70 volts AC on the OFF leg. They called me this morning to tell me I may have a wiring problem. I explained that you couldn’t measure the voltage without a load on the OFF leg since you could be dealing with stray voltage. I tested it this morning and he’s right there is 70 volts AC but you can ground the OFF leg and not trip the GFI, which would indicate stray voltage.

1. Didn’t turn the shaft because the motor inside is melted. The plastic fan is just melted goo.
2. See above, fan is goo.
3. Voltage is 250 across the ON legs.
4. Wiring is correct and wiring in the Pentair box is also correct. I contacted Pentair about the stray voltage, which is 24 volts AC at the relay but 3 mV with impedance, and when I told Pentair that I could ground the lug without tripping the GFI they said it’s okay. If you don’t know, the Pentair uses two relays for a 2-speed pump, first is a DPDT and the second is a 4-post-DT relay. Not sure why they use a 4 post but it’s a complicated relay inside.
5. The motor has two caps. Didn’t check them.
6. Checked out okay. I verified wiring with a meter and no electricity and nothing showed up as wrong or bad.
7. Didn’t think to check grounds but motor is grounded twice.

I think low speed was around 5-8 PSI.
No other electrical supply, just utility.

I think your idea is plausible but unlikely. The Pentair does both, turns the pump to high speed and turns the Jandy valve. Even if it did run on low speed I think it would be okay because the water to and from the roof is always primed and full. I don’t use a vacuum release. I really don’t see a difference in pressure when solar is on or off.

 

[jongig]

We need someone other than me to comment on this but that voltage seems unusually high.

Are you in the US?

Isn't most US single-phase residential voltage around 208-220. I don't even know if voltage that high would damage the pump but that 250v number jumps out at me.

I'm in NE-PA and we are here in the US. My utility company is PPL. I've complained in the past about the voltage and like magic it goes down and then goes back up over time. I put a call into them and I expect the same thing to happen.

 

[mas985]

I think low speed was around 5-8 PSI.

That is really high for low speed on a two speed 1 HP pump. If your high speed pressure is 14-15 PSI, then low speed should be in the 2-3 PSI range. Max head for low speed is less than 20 ft and for just the return side, you have a 15-22' depending on which number you use. So if those are correct measurements your pump is close to or at max head which means there is little to no flow rate and the heat will build up in the motor even at low speed. Do you feel any flow rate when on low speed?

There may be something in your plumbing which is changing from high speed to low speed. Check valves can behave this way and especially the axial spring load variety. They close down quite a bit with low flow rate so the head loss increases substantially.

Also, in an over voltage condition the amps will start to rise again slowly after about 5% over rated voltage. But even then, since the motor usually runs at an operating point that is below full load, it takes quite a bit of over voltage to drive the amps above the rated amps.

 

[jongig]

I am not sure of the PSI on low speed, thought I knew but maybe I don't. I connected an old 3/4 HP pool pump so that I could close the pool tomorrow. With this pump running I only saw about 6 PSI and I didn't notice a difference with the solar on or off.
I have looked into this enough and my educated guess at this point is friction loss. I did add a second check valve and yes it's the spring loaded Jandy. I never could find a head loss figure for it. The pool company called me today and have asked me not to close the pool tomorrow so that they can do further testing.

The 3/4 HP pump is an old Dayton and is a bronze pump. It doesn't have the flow but it runs fine and cool.

 

[JamesW]

That motor must have gotten very hot. Normally, the thermal overload shuts the pump off. It sort of seems like there might have been some sort of external heat source applied, but I can't think of anything that would do that.

It does seem that there might be a power quality issue.

Have you tested the voltage at the new pump under load?

Can you post a picture of the old pump?

 

[jongig]

I am using a old dayton 3/4 HP bronze pump for my backup and I checked the pressure with the solar on and off. With out is about 8 PSI and about 9 with solar. I also measured the wattage with solar on and off. With solar off the 3/4 HP pump draws 750 watts and with solar on it draws 742.

Attached are a few photos of the old burned pump. This pump was installed new on 8/20/11. The fan is just a melted mess and the windings look cooked. The back plate looks new.

 

[JamesW]

If the fan wasn't working, then the motor would rapidly overheat. Earlier this year, I had a motor overheat because the fan disintegrated. I'm not sure what happened to the fan. It was in a pump room, so I don't think that any debris got in the vents. Maybe there was some sort of defect in the fan.

Outside of the motor, I found small shards of PVC like plastic. The thermal overload turned the motor off until it cooled down, then the motor turned back on for a few minutes before shutting off again.

I am surprised that your motor got that hot without shutting off. You could look for white PVC like plastic near the pump to see if there is evidence of the fan disintegrating.

It's hard to tell, but the shaft looks corroded, which could indicate a leak that sprayed water into the motor.

It's odd that your pump is using more power with the solar off than on. Also, not having a vacuum vent on the panels is not usually a good idea. The vacuum can cause the panels to deform, especially when they're hot unless they are specifically designed to operate under vacuum.

If it won't affect your warranty, you might want to disassemble the motor to take a look inside.

There's a crack on the right board going to L1, but it does not look like enough to cause a problem.

If you get a chance, could you get the ratings off of the start and run capacitors. I want to see if they are dual rated. Since you have a double centrifugal switch, I'm thinking that the start capacitor is probably used for the high and low speed windings.

 

[FloridaSolarPro]

The Max-Flo II is a medium head pump, so it's not the best choice for solar

If you want a great pump for solar, get a variable speed or variable flow. The Pentair VS-3050 is awesome. You can dial in the exact flow rate you want, and with a controller, you can ramp up the speed when solar is on and scale it back when solar is off. It will save you a ton of money on your pumping costs - I'd say around 30-40% with solar pool heat, and far more without.

 

[jongig]

I noticed the watts up and down a bit so I did a 4 hour test with the replacement 3/4 HP Dayton pump. Solar off 1.53 KWH over 2 hours. Solar on was 1.50 KWH over 2 hours. Some pictures.