Hayward Tristar VS900 not priming

[RT17]

Hello. See several threads with same issue but no solutions yet. My pool and pump are just a couple months old, first time owner. Pump primed very good at beginning, filling all the way to the top. Not sure when the water level in the pot started getting lower, but noticed it about 2 weeks ago. Here are a list of possible issues:

1. Vacuuming one day didn't notice a large leaf at bottom and after finishing it was inside the pump strainer pulled against the diffuser input. Strainer was in place so don't know if this caused an issue or not. Pump was running high, so again didn't notice if it was running excessively loud or not.

2. Installed lid backwards and handles were not aligned perpendicular to pump. Felt lid sealed but don't know how big of an issue this could have been. Reinstalled it correctly and lubricated o-ring, but no change.

Pump is not leaking anywhere. Operating pressures are: 6-psi @ 1725rpm, 12-psi @ 2700, and 30-psi @ priming. Tested with running water at joints with no change. Re checked all joints and re-tightened. Looked inside diffuser and saw small clump of fibers (top right) but couldn't get them out. Cleaned out cartridge filter too, but water level at pump stays low. However, it does not go down when the pump shuts off.

Since it is not leaking I'm guessing shaft seal and o-rings are fine, but again I'm new to this. However, if the impeller ran a bit dry (with the leaf in the strainer) could the impeller ring be causing the issue? If so, should the shaft seal be changed at the same time?
Last post about this issue was about 2 years ago. Any updates from those members?

Thanks in advance

 

[mas985]

The picture looks like the impeller to me, not the diffuser. Normally you cannot see the diffuser from the exterior of the pump. The impeller could be clogged but I would not expect 30 PSI at priming if it were clogged. To check for sure, you need to separate the motor from the pump wet end and inspect the impeller directly.

But when you run at full speed, does the pump still not prime? If you are getting 30 PSI, technically, the pump is primed (i.e. water is flowing). Only if the filter pressure was close to zero would I say it is not priming.

If there is just air in the pump basket but water is flowing out of the returns, then that is likely an air leak.

 

[1poolman1]

Hello. See several threads with same issue but no solutions yet. My pool and pump are just a couple months old, first time owner. Pump primed very good at beginning, filling all the way to the top. Not sure when the water level in the pot started getting lower, but noticed it about 2 weeks ago. Here are a list of possible issues:

1. Vacuuming one day didn't notice a large leaf at bottom and after finishing it was inside the pump strainer pulled against the diffuser input. Strainer was in place so don't know if this caused an issue or not. Pump was running high, so again didn't notice if it was running excessively loud or not.

2. Installed lid backwards and handles were not aligned perpendicular to pump. Felt lid sealed but don't know how big of an issue this could have been. Reinstalled it correctly and lubricated o-ring, but no change.

Pump is not leaking anywhere. Operating pressures are: 6-psi @ 1725rpm, 12-psi @ 2700, and 30-psi @ priming. Tested with running water at joints with no change. Re checked all joints and re-tightened. Looked inside diffuser and saw small clump of fibers (top right) but couldn't get them out. Cleaned out cartridge filter too, but water level at pump stays low. However, it does not go down when the pump shuts off.

Since it is not leaking I'm guessing shaft seal and o-rings are fine, but again I'm new to this. However, if the impeller ran a bit dry (with the leaf in the strainer) could the impeller ring be causing the issue? If so, should the shaft seal be changed at the same time?
Last post about this issue was about 2 years ago. Any updates from those members?

Thanks in advance

One of the weird things about Hayward TriStar pumps, whether single or variable, is that they do not always fill the pot completely with water. That has been the case since they first came out as single-speed pumps many years ago. My 10+ year old EcoStar (same pump different name) sometimes does and sometimes doesn't. It has never caused any problems, you just get used to it.

Of all the ones I installed, only a couple filled with water (no air visible in the pot) upon installation. Many started to do so after a while. Your numbers are good. You should be able to remove that debris by using a piece of wire to push it from the outside of the impeller. It will require opening the pump. Be sure to lube the gasket before reassembling.

If you do decide to remove the impeller for some reason, you should always replace the shaft seal. It is US Seal PS-3890 or the much more expensive Hayward SPX4000SA2.