Problem: Air in system
Question/Theory: New multiport too small, creating too much suction head, causing air getting sucked in through valve body pieces?
Just replaced my old multiport due to internal damage. Couldn't find one of the same make, so bought a different brand (Hayward Variflo). This new multiport is physically smaller than the old one, but uses the same piping size (1 1/2").
The multiport's drain port leaks water in a slow drip, even after ensuring the spider gasket was seated (Hayward actually glued it in place). There is an ooze leak from the return port (the multiport has threaded fittings; apparently, I didn't get enough PTFE on that connection). PTFE on the other ports is smooth at the fitting-to-multiport (i.e., no indication of water leaks out or air leaks in).
After a few minutes running, the system gets a lot of air in it--I keep having to bleed the filter. This didn't happen prior to replacing the multiport. If I don't bleed, the pump shuts off and says there's an obstruction (too bad it doesn't say "suction" or "return" location). This didn't happen prior to replacing the multiport.
In Pumping 101, it says if there's too much suction head, the system will draw air in through valve body parts (like between the top and bottom of the valve).
Evidence of this phenomenon: when I changed from an open drain connection to a plug in the multiport drain port, the kW meter on my pump dropped noticeably (but air still gets in the system).
The more I write and think about it, it sounds as if the smaller multiport created excess suction head, so I need to change the multiport to a physically larger one.
Best to all,