3 way valve question

[Technikal]

I have a 3 way valve on the suction side of my pump that lets be choose between skimmers, main drain or both.

When "both" is selected, everything runs fine. However, if I change to either skimmer or main drain, air enters the system and your can see tons of bubbles run through the strainer and eventual out the Jets.

I assume this means a problem with the 3 way valve? It seems if there was a leak in the return lines it would show when "both" was selected. Should I rebuild/replace the 3 way or am I off​ base?

 

[pooldv]

I would take the valve apart and lube the o-rings with silicone grease to start with. More here, Pool School - Suction Side Air Leaks

 

[Jimrahbe]

T,

It could be the three way valve, but it could simply be the O-Ring on the pump basket lid.

Drawing from both main drain and skimmer is easier than drawing from just one of them, so the first thing I would check is the O-ring.

How does it look and when was the last time you lubed it?

One test is to take a garden hose and slowly run water over the pump lid and the three way valve. If either is leaking air then when you hit it with the water, the bubbles will go away.

I would also look at the input side of the pump, where the pipe comes in. If it is just a threaded pipe, these also can leak air under heavy suction.

Thanks for posting,

Jim R.

 

[Technikal]

I'm new to pool ownership so I've never had the valve apart. I'm still trying to enough to fire the pool service and vacuuming is the step I'm trying to figure out now - hence trying to divert the suction to the skimmers only.

I ran the hose along the different connections and the pump basket lid - didn't seem to make too much of a difference. It doesn't look like it's running dry or anything - so may it is just a case of the pump overwhelming the draw on a single line. Is it ok to have a little bubbling when doing that, or do I need to service the valves, etc?

I'm hoping to add a SWG and a 2 speed or variable speed pump motor sometime this summer, so will have the chance to really clean up the plumbing then...

Thanks for the feedback!

 

[Technikal]

Actually - after watching the videos here:
Centrifugal Pump Priming and Cavitation Videos

I think what I'm seeing is a cavitation. It's not a severe as what's shown in the video, but it's similar - and it would makes sense as I'm restricting the suction while keeping the pressure side open.

Given I have a single speed pump, does that mean I should never choose just skimmer or main drain? There is another valve on the last input into the pressure side that I could partially close, but given the pump is still going to be going full speed, it would seem like closing that partially would pressurize the filter, which is probably not a smart thing to do.

My pool service offers a 'Pool School' where they'll come out and teach you about your equipment. That might be a worthwhile investment for me...