Many of you guys know I got a house with a neglected pool with no manuals and it's been a guessing game ever since. Last year on closing I figured out that in addition to a main drain, 2 skimmers and 2 returns, I have a main RETURN. And in fact one jandy valve controls the side returns and another controls the bottom return whereas I thought the two valves controlled each side return independently.
Anyway, all the guides I've read have told me it's easier to get prime using the main drain. Well definitely not in my case. THe only way I can get prime is to close the main drain. Playing around the other day with my new found knowledge I've figured out why
Basically the prime was getting going a little bit from the main drain and then sending air back out to the main return located under the same caps. The main drain was then picking up the air that the main return was sending down and losing prime then immediately. Lather, rinse, repeat. Close the main return and viola, primes instantly.
The moral of the story is... uh.. I dunno, make sure to get labels on your plumbing! On the bright side the main return gives me a dedicated solar return and good dilution when I get solar so that's nifty indeed. Now I understand what the pool inspector meant when he said "oh this is already setup for a heater for you".