Hot pipes/pump

[dbanks2552]

Not sure if this is a pump problem, but wasn't sure where to post.
Came home today and pump was running but not circulating. Wife had noticed it was loud a few hours earlier but didn't see anything out of whack when she looked - cartridge filter pressure was 18 or so. When I went down to look at it, the Vac-Alert (SVRS) stem (PVC that was supporting it_) was bent over as though it have melted and the rest of the pipes leading to the filter were hot. there was little to no water flowing through the pump - didn't spend too much time looking as I turned it off pretty quickly. there was no pressure in the filter and the vac alert was also reading 0. I closed the drains (2 skimmers and one main (with 2 heads)) and the return and opened the valve on the filter. Yesterday I had cleaned the filters and when I restarted the system, I had tried to open the inflow valves one at a time to prime the pump better. I don't usually need to do this but the prime seemed a bit slow so I was just messing around with it. when I had it closed down to one skimmer, I tripped the Vac-Alert. I opened all 3 inflow valves then and reset the SVRS and got full prime with no problem. Everything sounded good and the pressure in the system was good (16 at the filter and 0 on the Vac alert) so I went on with my day. swam in the pool later that night and all looked well.
Not sure what else to tell you as I don't know what the issue is. If the SVRS tripped again, would it heat up the pipes? Seems the heat must be coming from the pump (just checked it again and it is still hot after an hour.) Did the pump lose prime and then heat up and then the PVC melted? What would cause that?

Thanks for any thoughts or help.

 

[CNJ_EC]

Would be helpful to know what specific equipment/configuration you have ... most likely a:
Suction Line Leak or Blockage;
Low Water Level;
Damaged Impeller:
Damaged Diffuser.
Might also be a blockage after the pump ... you mentioned that you closed the valve on the return and also opened the valve on the filter ... was it a multi-port valve and have you double checked all of the valve positions?

Also, did your pump not shutdown when the vac-alarm occurred?

 

[dbanks2552]

Have 3 lines coming in from pool and combining to one which has the Vac-Alert on it then goes to Pentair Whisperflo pump. that leads to the cartridge filter then to the heater then the chlorinator and then the return which has 4 jets into the pool.

I do remember that when I opened the pool and was trying to backfill the lines (this was about 2 mos ago,) that one line would not fill - i could just keep pouring water into it. i did that for about 15 minutes before I just went ahead and started the system. it appeared to catch fine and all lines ran with no air so I didn't figure there was a leak. again, it's been running fine for the last couple mos.

I'll try to restart tonight without the Vac-Alert if I can and see if anything draws. Have to go to work now. The system is designed to just let enough air in to release pressure when the Vac-Alert is tripped but still allow enough water in to keep the pump running and not overheat, so, no, the pump did not shut off when it tripped it just lost pressure (5-10).

The valve on the filter I opened was the release on the top of it. it just allows the air out (or in in this case) when the filter is filling

All valve positions were open when I went to check and I'm sure it was running fine the evening after I changed the cartidges

Thanks

 

[CNJ_EC]

db ...

You might want to kill power to the pump - TURN OFF/LOCKOUT THE BREAKER & DISCONNECT - then remove the strainer basket from the pump - clean inside the difusser assembly and check how easily the impeller rotates. Does the inside of the diffuses assembly and the surface or the impeller feel smooth or rough? Smooth is good. If it's rough, it might be a sign of cavitation, and could explain your pipe heating problem. Depending on the age/conduction of the pump's motor(dry side), you can do a rebuild or replace it with a VS style that might reduce your power consumption.

Regarding your 3 suction lines .... are there equipped with any sort of a valve before hitting the pump?

If so, use the valve to isolate each of the suction lines. Let the pump run for at least 5-10 minutes and check for heat build-up at pump case near the strainer basket, impeller/diffuses area, the seal plate area, and piping before testing the next line.

You might want to apply some lube-seal to the strainer lid O-ring and any other O-ring/seal/gasket that has been recently opened/closed.

Does the pressure at your 4 sidewall return jets appear to be OK?
The suction line that wouldn't fill ... was for a skimmer or main drain?
Is your equipment pad outside?
How old is your pump? Any idea as to how many run hours on it?
Do you have unions on the plumbing to/from the pump? If so, make sure they are tight and not leaking/sucking air on the suction side.

Good Luck!

 

[dbanks2552]

Sorry I've been absent. I appreciate your help. I did turn off the power and rotate the impeller. the feel was a little grainy rather than smooth, but it rotated easily enough. Since the pump is still under warranty I did not investigate further and instead called my pool builder. Pump is only 2 years old. He took the Vac Alert off and said it wasn't necessary after the final inspection had been completed since there are 2 drain covers for the line. While he was there initially he pointed out that the fittings connecting the pump were loose. those were tightened up and after he left I cut the Vac alert off and plugged the pipe with a rubber plug. I was able to get prime at that time. So I still don't know why I lost prime in the first place, but after everything heated up, I thing the connections got loose and that is what caused me to think I was not getting any draw from the pump. of course it is possible that the fittings were loose to begin with and that is what caused me to lose prime. Anyway, all's well that ends well. thanks again