Air In Pump Question

[cdoz35]

Hello everyone. I have been a 2 year reader of the forums and want to thank everyone for the wealth on knowledge available on this forum. There a truly some amazing people, that probably don't realize how many people they have helped by answering questions, and then other people with similar problems also head the advice. I recently joined the forum, and want to tell you a little bit about my pool, and the problem that I cannot seem to figure out.

We moved into a new house last year, that has a 80s model inground gunnite pool. The pool was not in the best shape, but I have been able to get it in operating condition. It could probably use a new coat of plaster, but it holds water good as it is and works great in this Texas heat to cool us off. I have been using the BBB system and could not be any happier. The water has stayed clear and clean. What a awesome trouble free system. As long as I put a few minutes in each day the pool has stayed in tip top shape.

Anyways I have a problem that for the life of me I cannot get figured out. The pump is getting air in it, but I can't make sense of where it could be coming from. Let me tell you about the setup.

The pool has one main drain, and one skimmer. Both return to the pump station through their own 1 1/2 pvc pipe. When they arrive to the pump station there is a Jandy valve that allows me to select to pump from the skimmer, the main drain, or both at the same time. This is where I am dumbfounded. I get very little to no air bubbles in the pumps filter basket if I am drawing from both sources at the same time. However, if I switch to just on or the other I am getting a lot of air into the pump, sometimes enough to almost loose prime. This makes it very hard to run a pool vacuum, because I cannot divert the full pump suction to just the skimmer without getting a lot of air, and I do not want to ruin my pump.

I have checked every thing I can think of. I have disassembled the Jandy valve and checked the O rings in it, and they all seem to be in good shape. I have checked the fitting where the plumbing runs into the pump and cannot find any problem there. I have also double and triple checked the filter basket o ring. I have tried to run water over all of the fittings and cannot get anything to change. Correct me if I am wrong, but I feel like the suction side leak has to be coming somewhere between the jandy valve and the pump, or I would not be sucking air from both the skimmer and the main drain. I am thinking that when I have both sources open the pump is not having to suck as hard, so it is not sucking in the air as bad.

Maybe I am looking at this all wrong, any advice or things to check would be greatly appreciated.

One more thought I had, but I think it is probably far fetch. The pump has done this ever since we moved in, so I don't have nay background on it. Is there a chance that the pump is too over sized to pull through just one 1 1/2 pipe at a time, that it is causing cavitation which would lead to the air bubbles? I know this is far fetched, but I wonder if it could be a possibility.

Thanks in advance for any advice

 

[Texas Splash]

Even though you have inspected/tested several areas already, you might consider trying cellophane/clear wrap. We usually mention the water thing or shaving cream, sometimes even smoke., but I really like the idea of smothering an area with clear wrap. I'm not so sure about the pump angle, but that 3-way still has my attention, even with a previous disassembly. Just the fact that everything is fine when pulling water form both sources makes me still focused on that 3-way. I'm very curious to see how your scenario works-out. Maybe some others will have an idea or two as well. Keep us posted.

Oh, when you get a chance, please update your signature and perhaps post a pic of your equipment pad if possible.

 

[bradj]

Even though you have inspected/tested several areas already, you might consider trying cellophane/clear wrap. We usually mention the water thing or shaving cream, sometimes even smoke., but I really like the idea of smothering an area with clear wrap. I'm not so sure about the pump angle, but that 3-way still has my attention, even with a previous disassembly. Just the fact that everything is fine when pulling water form both sources makes me still focused on that 3-way. I'm very curious to see how your scenario works-out. Maybe some others will have an idea or two as well. Keep us posted.

Oh, when you get a chance, please update your signature and perhaps post a pic of your equipment pad if possible.

Sounds like it has to be the three way... if you've inspected it and still have issues.. replace the thing.

 

[cdoz35]

Here is a picture of the pump station. Sorry it is sideways, I couldn't figure out how to rotate it. I feel like there is a lot of unnecessary 90's on the return side, but I can address that later. Thank you for all the ideas, and confirming my suspicion. I will try replacing the three way valve. It is all old and prolly needs replaced anyways.

 

[Kmaz]

Your thinking is not far fetched at all,the pump is being starved for water when only one line is drawing.
Kris

 

[cdoz35]

Ok so I am completely out of ideas now. I completely changed out the three way Jandy valve, and all the fittings between it and the pump. New orings a seals in everything. I am still getting air in the pump. There is definitely more air whenever I pull from only one source. But there is a little bit even when drawing from both. I am at a complete loss. The only thing I can think of is that both suction lines have a leak under ground somewhere. Another thing that makes me think the leak is up close to the pump, is that whenever I switch to drawing from just one source it instantly gets air in the pump. Seems like if it was underground a ways from the pump it would take a second or two for the air to arrive at the pump ( I am only guessing at this so that line of thinking may be wrong). I am open to any ideas. Unless anyone has any suggestions I guess my next step will be to pressure test the return lines. Thanks for any help.