My second burned out pump

[FloridaSolarPro]

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.

Yeah, that's a lot of energy. Most of the day my pump runs at about 475 watts. I'm saving a boat load of money and still getting the same turnover as my old 1.5HP pump. if you are replacing a 3/4HP pump, you would likely see a power draw around 175 watts over much of the day.

It's a hefty investment, but worth it.

That power draw sounds dead on for a 3/4HP pump, and you won't see a big difference with changes in back pressure. Your flow rate will just change.

 

[jongig]

More Pics

 

[jongig]

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.

I am interested in the Pentair VFD pumps but this is what came with the pool and it worked very well and I didn't see that it was worth the money to change it. The pump is on low speed for 8 hours a day and only on high speed when the solar is on. It's hard to justify the Pentair when you're only using the pump for 4 months of the year. I had looked at the Pentair Intelliflo 011018 pump and it would work great with my Pentair Easytouch.

 

[JamesW]

I think that your system needs to be thoroughly inspected by a qualified service person. I think that there are probably a few problems that need to be addressed. The fact that the motor is using about the same or less energy with the solar on than off indicates a problem.

[edit]With the solar on, the pump is probably closer to its Best Efficiency Point (BEP). Therefore, as Mark points out, the energy use can be the same, or lower.[end edit]

 

[jongig]

I think that your system needs to be thoroughly inspected by a qualified service person. I think that there are probably a few problems that need to be addressed. The fact that the motor is using about the same or less energy with the solar on than off indicates a problem.

It's a 20 year old inefficient pump and with the difference of only 1-2 PSI with solar on it's just putting the pump in it's sweet spot. It's also pumping a lot less water and is a very heavy solid bronze pump. With a low or medium head pump it would make much more of a difference.

I don't really know anyone more qualified than I am and I can't figure it out for certain. My guess is still that it was a slow death because of too much head and then boom it happens that the fan, which is plastic, finally gives out. The motor keeps running and becomes catastrophic. It does look as though the pump was spinning without the fan. The only way I think we'll know for sure is to connect the same pump and take pressure readings at the pump and running amperage readings.

My problem here is that head loss calculations have not proved to be too much for the pump according to Haywad. Hayward says that 16 PSI is just fine for the pump. One little note here is that the 16 PSI is at the filter that is after a few 45 degree fittings and the Jandy check valve. Lets consider another 2 PSI or 4 or who knows since I can't find a head loss figure for the Jandy. Maybe the pressure on the pump was just too much. I've not found a high pressure figure for the Hayward.

 

[mas985]

Actually maximum load on a pump motor is near run out or the right most portion of the head curve where head loss is a minimum and flow rate is a maximum. Operating points on left side of the head curve is a lower load on the motor (moves less water) so the motor uses less energy and will tend to run a little cooler than on the right side of the head curve. Except of course at the extreme left of the head curve where no water can flow through the pump and heat can build up. So you are more likely to burn out pump if the operating point is too close to run out than if you run a pump will a lot of head loss.

 

[JamesW]

Ideally, the pump should be operated close to its best efficiency point. I think that for your original pump, that would be a Total Dynamic Head of 47 feet and a flow rate of about 43 gpm.

Here are a few suggestions:

1) Use a flowmeter to verify the flow rate going to the solar panels.
2) Use a vacuum gauge to measure the vacuum pressure.
3) Make sure that voltage does not exceed 250 volts*. Perhaps you could use an eMod and/or some sort of power conditioner.
4) Periodically measure motor temperature using an infrared thermometer or install a thermal protection device.
http://www.harborfreight.com/infrared-t ... ?hftref=cj

*Excessive voltage (typically above 110 % of the rated voltage (230 volts X 110 % = 253 volts)) can cause magnetic saturation of the motor core, which can lead to overheating.

An infrared thermometer will only measure the outside temperature of the motor, but the winding temperature is the most critical factor. Therefore, it can help identify excessive heat, but it is not as reliable as a device designed to measure temperature of the windings.

 

[jongig]

Well it's too late in the year to figure this out and so it will have to wait until spring. My thought still is that I just have too much head and the pump slowly goes bad and then melts at the end. Hayward doesn't seem to agree but the pool company has and is going to replace it. I will replace the pump most likely with the Pentair intelliflow and with the extra power I shouldn't see the same problem again. I purchased a flow meter but the company sent the wrong one and so I didn't get to see what the flow was last week with the 3/4 HP Dayton pump. Attached is a picture after closing the pool. This pad is about 50 feet from the pools edge and I put it there because I didn't want to see this stuff from the pool. Also the big pumps are loud. The plumbing in bags just to the left of the 2 big pumps is the suction from the ground and where the Hayward pump was. On the very left is where the Pentair salt cell goes. You can see the two pipes going up to the roof solar and the black exchanger on the right gets heat from the house solar system. Two solar systems. All the plumbing is 2 inch except the 1.5-inch to waste from the Hayward sand filter. After the salt cell the plumbing goes to 1.5-inch poly in the ground for 80 feet back to the Aqua Genie. The suction side of the Aqua Genie to the pump is 2-inch poly.

 

[mas985]

My thought still is that I just have too much head and the pump slowly goes bad and then melts at the end.

At the risk of repeating myself, more head loss means LESS power, LESS amps, LESS heat, LESS stress on the pump. Not more. Pumps work harder when the flow rate is higher not lower.

 

[jongig]

I found a picture on my old iPhone of the old pump in place.

 

[jongig]

My thought still is that I just have too much head and the pump slowly goes bad and then melts at the end.

At the risk of repeating myself, more head loss means LESS power, LESS amps, LESS heat, LESS stress on the pump. Not more. Pumps work harder when the flow rate is higher not lower.

From my previous post " of Posted: September 26th, 2011, 5:40 pm ", I said "I never measured amps and can't now but if the pump is restricted whouldn't it run cooler not hotter?".

I have no experience with pool pumps but I am familiar with pumps in the water industry and you’re right to a point. On a low-pressure pump I believe you can pass rather quickly into actually slowing the motor down and causing the pump to heat up. Hayward classifies this pump as a medium head pump but I would classify it as a low-pressure pump.

I don’t think I received much help from Hayward but there has to be a reason and it’s not the electric or the way it’s wired. I do not understand how heat ruins a pump that has thermal overload protection. I was told by a technician at Hayward that they’ve seen this before and that they changed the motor to a different HP and the problem went away. The example they gave me was after three motors failed. I sound like a broken record, if the pump overheats shouldn’t it just stop until it cools down?

 

[mas985]

On a low-pressure pump I believe you can pass rather quickly into actually slowing the motor down and causing the pump to heat up.

Not for a properly running pump. The only way to slow down an induction motor is to increase the load beyond the rated load where the slip will start to increase. However, pump motors are rated for the entire head curve and the highest load on a pump motor is the right most point on the head curve so you really can't overload a pump motor unless there is something stuck in the impeller or bad bearings are adding extra friction.

 

[JamesW]

Something is definitely off with the system based on how many problems you are having. It could be that the water sat in the pump with no flow and just overheated the pump. It could be excessive voltage. It might be that the second solar system dumped a lot of heat into the pump.

I'm thinking that whatever it was happened very fast to melt the plastic fan because the thermal overload should have cut the pump off unless the pump heated up so fast that the thermal overload didn't have time to heat up before the pump failed.

I think that it might be worthwhile to do a failure analysis of the pump motor starting with testing the thermal overload to see if it is working correctly. Try heating it up to see if it opens the switch at the correct temperature.

Also, pull the motor completely apart to get a good look at the windings. Perhaps you could take the motor to a local electric motor repair shop and ask them to see if they can determine what went wrong. There will be a charge, but I think that it is worth it to help prevent further problems.

When you install the new pump, I recommend as much monitoring as you can reasonably manage. Temperatures, pressures, flow rates, voltage, current etc. Only by getting enough data, can you determine what is causing the problem and hopefully prevent it.

 

[jongig]

@James.
I could not get permission to open the pump so I didn't and they've since taken the pump. I would have loved to take it apart. The pump was working just fine on that day and once the pump is on it doesn't shut off until 5 PM. I can tell by the House-solar data logger that it was not a very sunny day and the solar was on and off. The house-solar is an automated system and was heating the pool water. At 14:00 there is a delta-T in the log and at 14:40 on there was no delta-T, which would mean there is no exchange meaning no pump. The automation switched off the pool exchanger at 16:00 when the temp went above 140 on the LWT side. I can't tell when the Pool-solar is on or off but it would not have been on much that day. The Pentair automation operates the Pool-solar and the temp. sensor is on the pipe on the roof in direct sunlight, the water would not be that warm. There was no voltage issues and although a bit high it wasn't enough to cause the motor to melt. I have no problems anywhere that I can find except that I've had two pumps fail.

Attached is a picture of part of the data log from the House-solar and look at the commas for separation. Date, Time, Entry Water Temp, Leaving Water Temp. The House-solar system is off when below 100 degrees.

 

[JamesW]

Looking back at the motor pictures, I'm not sure why exactly, but I get the feeling that the motor was a reconditioned/rebuilt motor. I don't think that it was a new motor. The motor shaft is too rusty at the front and back to be a new motor. Even if water got into the motor, there would not be that much rust that fast. The shaft is high quality stainless steel and there is no corresponding corrosion in the back end of the motor.

Also, the labels and motor color do not look right. The motor looks like it was repainted and the labels stuck on.

Did the pool company change out the whole pump or just the motor?

Was the pump basket damaged in any way from the heat? When those plastic baskets get too hot, they will tend to warp and shrink. It would have also been helpful to get a look at the impeller to see if it was damaged or warped.

The voltage at the time of failure was 254.3 volts, which is definitely too high, but I don't know if it was enough to cause the problem.

The solar heat exchanger is right next to the pump motor. At 15:20, the temperature is 139.5 F. That would have radiated out a lot of heat next to the motor. If the motor was already overheating from excessive voltage, then the additional radiated heat from the exchanger, and the sun might have been enough to cause the rapid failure of the motor. Perhaps the fan was damaged, which would cause the motor to rapidly overheat.

 

[jongig]

Looking back at the motor pictures, I'm not sure why exactly, but I get the feeling that the motor was a reconditioned/rebuilt motor. I don't think that it was a new motor. The motor shaft is too rusty at the front and back to be a new motor. Even if water got into the motor, there would not be that much rust that fast. The shaft is high quality stainless steel and there is no corresponding corrosion in the back end of the motor.

Also, the labels and motor color do not look right. The motor looks like it was repainted and the labels stuck on.

Did the pool company change out the whole pump or just the motor?

Was the pump basket damaged in any way from the heat? When those plastic baskets get too hot, they will tend to warp and shrink. It would have also been helpful to get a look at the impeller to see if it was damaged or warped.

The voltage at the time of failure was 254.3 volts, which is definitely too high, but I don't know if it was enough to cause the problem.

The solar heat exchanger is right next to the pump motor. At 15:20, the temperature is 139.5 F. That would have radiated out a lot of heat next to the motor. If the motor was already overheating from excessive voltage, then the additional radiated heat from the exchanger, and the sun might have been enough to cause the rapid failure of the motor. Perhaps the fan was damaged, which would cause the motor to rapidly overheat.

They handed me what I believe was a completely new pump and motor. No way is the shaft stainless, it would not look like that. There was no sign of water anyplace around the pump when I inspected it within 2 hours of it's failure. The motor was new looking but now looks baked. I handed them the broke one and they handed me the new one. He said he was keeping the box to send the broke one out. It took a few days to get the pump.

No damage to the pump but I didn't take it apart to look. No damage to any plastic parts that I saw. The high voltage was that high but the constant will land in between the two figures.

The solar exchanger is pool water in the shell so the shell would not be warmer than the pool water. Based on the max that I ever see in BTUs, 30,000, exchanged in the pool exchanger and a minimum of 25 gallons per minute of pool water flow the highest temperature in/out and shell would not exceed 2.4 f degrees difference. In the House-solar I have a flow meter. It wasn't a hot day and the pool water was 72 f. I've had the pool water 85 f on very sunny hot days and no failure. You and Mark have posted some very good questions and information as well as others but this just seems to be a mystery. I would hope that Hayward takes the motor apart and is able to offer a reason. They thought that maybe the motor was under strain from too much head. I stated to them that in my water industry the pumps run cooler under added load and they had never heard that. In the early part of this I got an idea that they would try to deny my warranty based on the results of the technician from the pool company when he measured voltage on the off leg to the pool pump.

I still have a question about the Pentair and Pentair can't answer this. Why did they use a 4 post DT relay to piggy back the DPDT motor relay? They could have easily used a second DPDT or a SPDT relay and not complicated the heck out of the installation. When I wired the two relays I didn't pay much attention to the setup but just to making sure I followed their diagram. Now that I've analyzed the diagram it makes no sense.

Picture attached is the two relays. The one to the left is the original and on the right is the two speed relay. The two black wires off the relay on the left are the two 120V legs, also attached at the same lugs is a white and yellow wire, 240V that goes straight up to the salt cell. The wires to the pump are White-common (from the left relay), Red-low speed and Black-high speed (from the right relay). The Pentair automation turns on the left relay which turns on the power and the right relay offers either low or high speed. Wiring is 10 G to the relay and 12 G to the pump which is just 4 feet away. So complicated when they needed only a SPDT relay.

 

[jongig]

I asked the Hayward technician if the motor would run with both of the speed legs under power, he didn't know. Does anyone know the answer to this?

 

[jongig]

From Pentair. Sorry my picture is sideways.

 

[Ohm_Boy]

Pretty much dead-on.
These are double-make/double-break, which basically means that when the switch opens, it opens at two points instead of one. It helps prevent/extinguish arcing.
The relay on the left is essentially a pair of N.O. contacts operating together. The relay on the right appears to be a pair of N.O. contacts and a pair of N.C. contacts. Pairs are doubled up to provide twice the current capacity. NC contacts feed one speed, NO contacts feed the other. It all adds up to a DPST feeding into a SPDT. This is actually a common arrangement in industrial controls.

 

[Ohm_Boy]

Here's the simplified schematic:
[attachment=0:2jnbtgo3]hilo.gif[/attachment:2jnbtgo3]