Trapped air in suction line

[bkinsey]

Hi TFP community!

This is my first time posting in this forum.

I am a recently new homeowner of a house that has a pool. Its been 2 years now, the pool has been working good up until recently. I had some landscaping done to build a retaining wall and didn't know where the in-ground pipes were installed; I found out the hard way that most of the pipe was installed around the concrete patio surrounding the pool. However, the landscapers had broken an underground pipe; they quickly replaced it and let me know about it, and I thought all was good until I decided to open up the pool and start up the pump. The pump doesn't draw water as fast as it pumps it out, so the basket level is pretty low, or you see that gushing effect of water coming in and getting pumped out quickly. I used a snake and endoscopic cam and found a significant amount of air in the newly repaired section of pipe.

I have a few questions:
- What's the general practice for removing trapped air in a suction line?
- Is there a recommended pressure test kit or equipment people can recommend? I saw some fancy nice ones but they cost an arm and a leg.. maybe I just need the right plugs or valves? I've dug up most the lines and I don't have any problem working with the PVC. I think it would be wise to see if my pipes can hold pressure.
- Does anybody add sanitary tees to their pool lines? It seems like it would make it easy to snake and see what's going on inside the pipe or to remove blockages if the need ever came up. (Although between the skimmer and the pump doesn't seem like a lot of opportunity for large debris to get sucked into the line.. but its possible.)
- What's the guidance on plumbing suction lines, do they always want to slope up from the pool to the above ground pool equipment pad, or would level pipes be fine? The repaired section of pipe looks like an upside down U, which is why air is stuck in their blocking the line. I'm trying to figure out if I'll just want to re-do that section of the line, or if the pipe was full of water, would suction be good again. (And if the latter, how to remove that air and get the pipe filled up with water)

Please don't refer me to pool professionals.. I think with the right knowledge and tools I should be able to get this fixed, I just need some guidance.

Thanks in advance for any help!

 

[mas985]

Welcome to the forum!

- What's the general practice for removing trapped air in a suction line?

Water flowing through the pipe will push out the air automatically, IF everything is working properly. Your problem is not the removal of trapped air but the leakage of air into the pipe. Most likely they did not fix the pipe properly and it is allowing air into the lines.

 

[Jimrahbe]

b,

Welcome to TFP.. A great place to find the answers to all your "Crazy" plumbing questions...

Even if there was a little air in the suction line, I can't see how it would prevent the pump from priming and completely filling with water. I could see how the air might be passed through and back out into the pool with some noticeable bubbles, but that should be pretty short lived..

The first thing I would check is to make sure the water is at the middle of the skimmer and that the weir door is not stuck up. The next things I'd check is to make sure there are no obstruction between the skimmer and the pump. Maybe they broke your suction line in more than one spot... ???

Thanks,

Jim R.

 

[bkinsey]

Thanks guys for the direction! I also have a hot tub and when turn my valves to get water from the hot tub and return water to the hot tub, the pump works just fine. So there is definitely something wrong with the pool lines.

I'm still digging up the lines to try and better understand how they plumbed the pool lines. We haven't been able to snake into either skimmer side: one skimmer goes out and joins a T, which is odd.. have to find out where else its going, and the other skimmer is doing something under the concrete and haven't found where it meets the intake line to the pump. The partially good news is that I do feel suction from both skimmers when the pump is running. Trying to dig and assess more, but I'll probably end up cutting a pipe at some point and then snaking in to see if there are any blockages. If not.. maybe its a cracked pipe or unsealed pipe and I'll have to find where it is and replace it. Any recommendations on pressure testing kits for pools? (Or anything that is economical and useful to test pressure in sections of the pipes)

 

[Jimrahbe]

b,

Sorry I have no recommendations on pressure testing...

So, you have two skimmers... and I assume a main drain... How many input pipes does your pump have? The spa plus what else from the pool?

A picture of you equipment pad showing the suction side of your pump and any inputs might generate some ideas..

Thanks,

Jim R.

 

[proavia]

You stated it was working fine before the retaining wall build. You may wish to look around anywhere the landscaper dug. Possibly a second area that they broke a pipe or maybe a poorly glued or unglued joint in the area they repaired.

You have basically ruled out the pump basket lid as the spa suction alleviates the bubbles. So there is probably a suction side leak in the
Skimmer or bottom drain lines coming from the pool.

 

[bkinsey]

After a lot more digging, we found a cracked pipe we believe is causing the issue. It was actually a 90 elbow that cracked and was pulling in air. Now we're trying to see how we want to fix it. (there is the quick solution, a minor improvement solution, and a major improvement solution)

Thanks everybody for responding!

 

[peirek]

Permanent solution is the one I would vote for.