Mysterious Priming Problem

[totalcareaz]

Hi All,

I have a 10 year old pool which has a Whisperflo Pump, Newer Pentair Clean and Clear Filter, and a Ruud heater. Recently the pump began having a strange issue. It won't prime no matter how many times I fill the basket (I've done it till I raised the pool level to the top from filling it). I've checked for supply side leaks, replaced the pump basket lid, diffuser, and impeller so the pump is brand new inside. Interestingly if I pre-fill the filter by running the pump while filling with a garden hose until water spews from the air bleed, shut pump off until basket is over flowing, throw the lid on and it primes right up! No air in the basket and it'll stay primed till the next time it shuts off and I have to repeat the process. I am stumped as to what pre-filling the filter is doing and what I am missing here. Restriction on the return side? Hope someone can help as as this time I've removed the "on" tab from my timer so it doesn't sit and run dry but I have to re-prime it every day!

Thanks in advance for your ideas!

 

[needsajet]

After priming, do your returns feel like they're getting the same amount of flow they always have?

Could you post a picture(s) that show your pad and all valves?

How much above pool water level is the pump?

 

[totalcareaz]

Thanks for the reply. Yes the returns feel about the same and the pressure on the filter is sitting right where it normally does when clean. There is no valves on the system but I will try and post a picture. No changes have been made to the system for 10 years other than a new heater and we replaced a line that cracked but this happened before doing those things. I should have noted this is actually a spool, more like a spa.The pump sits on the same level as the spool deck so slightly higher. Thanks again for your input!

 

[needsajet]

Frustrating! The only thing I can think of is a blockage in the volute. I'll put up the bat signal for a pump expert.

Pictures are almost always helpful.

Listing your equipment in a signature is helpful (almost essential) - there's instructions linked in my signature (read before posting) which will help you get the best possible advice here.

Here's a few links:
Pool School - Pump Basics
Pool School - Troubleshooting your Pump/Filter
How To: Determine Why A Pool Pump Wont Prime - YouTube
Self-Priming Pump Basics Pt. 1: Introduction - YouTube

 

[duraleigh]

In a good, tight system, the pump basket never empties when you shut off the pump so it stays primed even with the pump off.

I know this is not exactly your question but it may be easier to simply fix the priming issue with a check valve or finding the leak(s) that is allowing the water to drain out when you shut down the pump.

 

[JamesW]

Look under the pump for a leak while it's running.