Trouble Blowing Out Returns

[cgoll]

Hi! We have had our inground pool for 8 years now and I've always closed it myself by the same method; using a shopvac as a blower to clear the lines.

This year something is different. I can not get ALL of the returns to blow out properly. We have one line from the heater that splits underground to return water to 3 eyeballs on the pool walls and 2 eyeballs on the steps. Drained the pool to the point where the eyeballs on the steps are just, but completely, above water. The other 3 are submerged. No different than past years.

I usually plug all five returns, have a helper apply air pressure to the main return line while I go around and open one return at a time, blow the water out, replace the plug and go on to the next. I usually repeat the cycle until I'm confident that all the lines are clear.

This year I was able to get air to come out of each one, but not all in each cycle! There was always one that wouldn't clear, but not always the same one. When I would remove the plug expecting air to come out, instead I can feel the water being sucked back in! But if I go to a different one, air rushes out.

Very frustrating! I don't understand why it could be doing this. (BTW, clearing the skimmer lines was no problem.)

Can anyone help?

Thanks!

 

[JamesW]

Eyeballs at steps are sometimes venturi fittings and have an air line going straight up from the fitting to an air intake control fitting. If the air intake fitting is not sealed, then some air pressure will escape. Sometimes the venturi air line will have a leak, which might not cause any water loss.

If the step returns are not venturi fittings, then I would suspect a leak somewhere in the lines.

 

[PoolGuyNJ]

Sounds like a collapsed line or a separated fitting.

Pools blow out the same, the nearest to furthest, unless something is broken.

Something to try: Try blowing the lines from the step furthest from the equipment. Close the multiport first.

Scott

 

[cgoll]

Guys,

Thanks for the replys!

First; There are no air intake controls for the step eyeballs.

So, please tell me more about how a leak would cause this symptom.

In no way am I saying you are wrong, especially since you both suggested it, but I am trying to understand how it would cause this.

I do fear something serious has occurred because I have seven prior years of closings that didn't go like this.

I appreciate and await your replys!

Chris

 

[JamesW]

If the line has a leak somewhere, then the air pressure will escape. When there is water in the line, the pressure is high enough because it takes more force to push water through a small crack than air. Therefore, you will be able to clear the lines until the air gets to the leak.

Sometimes you can hear the air escaping if you listen to the ground directly above the leak. Air escaping can make a hissing sound and/or a bubbling sound if the pipe is surrounded by water. Geophones make it easier to listen. To confirm or rule out a leak, the next step is to do a pressure test.

http://www.leaktools.com/products/liste ... ophone.php

 

[msgtdan]

I've read of farmers using homemade PVC stethoscopes to find irrigation leaks. Large diameter DWV fitting reduced down to pipe long enough to listen to while standing. Move it along the surface until the leak is heard.