Changed multiport; now air in lines & pump says "obstruct'n"

ajgiii

LifeTime Supporter
May 31, 2008
27
North Virginia
Hi All!

Problem: Air in system

Question/Theory: New multiport too small, creating too much suction head, causing air getting sucked in through valve body pieces?

Background:
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.

Thoughts?

Best to all,
AJGIII

 

Bama Rambler

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2009
23,047
SouthWest Alabama
Unless your system is plumbed backward the multiport can't leak air in when the pump is running. Air has to come from the suction side. I suspect a coincidence in changing the multiport and the air getting in the system.

The most common places for air to get into the system is the pump strainer basket lid or the skimmer sucking it in due to the weir not working correctly or the water level being a little low.

Now, if your MP valve is new and it's leaking it should be under warranty and should be repaired or replaced. Even if it's not the cause of the air it still shouldn't leak when the pump is running.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
31,713
Sebring, Florida
Just reinforcing bama's post....multiport is on the pressure side of the system and cannot suck air. Your air leak is somewhere between the impeller and the skimmer(s)
 

ajgiii

LifeTime Supporter
May 31, 2008
27
North Virginia
Hi Guys

Thank you for responding. One of the first things I checked was pool water level. It is fine. However, I recall that my skimmers haven't had the draw they normally do and was going to go out just now to vacuum the lines to see if I get anything out of them.

My next step was to check the impeller for something caught in it. And, I'll triple check my pump/return lines to the multiport to ensure they are correctly plumbed. After that, I'm stumped.

Will report back.

Best regards.
AJGIII
 

ajgiii

LifeTime Supporter
May 31, 2008
27
North Virginia
Re: Changed multiport; now air in lines FOLLOW UP

I tightened the plugs on the multiport that cover unused ports. While these plugs did have new o-rings in place, and they were not leaking, tightening them significantly reduced the air in the lines.

This agrees with what is presented in the "Pumping 101" discussion on this site!!!

Way to go TPC!!! :wave:
 

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