Pool Closing question: Main Drain

[bfang711]

hi guys,

I tried to follow the instruction in this forum to close the pool, everything has been working well so far. Just one question about the main drain blow out.

I attached air compressor hose on the drain of the pump, and switched the multi-valve port to receip. (I already backwash and open the drain plug of the filter, so I think I can bypass the filter. Please correct me if I am wrong.) After blowed out and blocked skimmers, return lines, main drain is the last one that bubbles coming out. Then I turn off the valve switch of the main drain, followed by unplug the air compressor. Now the question is how should I check if there is any (air) leaking from main drain valve that I just turned off. The valve level is above the pool water level and the main drain is at 9' deep in the pool. The main drain valve actually works well for water, the evidence I have is when I vaccum the debris of the pool, I turned it off, leaving only skimmers on. I can definitely tell that the main drain valve works for water. But I cannot tell if it works for air. I wonder in my case, if there is any leaking of air, during the winter, is the pipe gonna freeze and cracked? (Last year, the pool company did winterizing for me and this was all what they did and it works. I am just a little bit worry, since it is the 1st time I did this myself.)

Btw, I live in Long island NY state.

thank you.

 

[Catanzaro]

If the main drain in the pool is producing small air bubbles, then the valve is leaking. You could also install a black expandable plug in the suction side of the pump. This will keep air in line if valve fails. Also close skimmer valve to the main drain as well or air from main drain can leak out to skimmer lines. This could be possible depending on your plumbing. My Jandy valves go from 90-360 degrees and can be controlled with pins. Thanks

 

[PoolguyinCT]

Slamming a plug in pump, to compensate for a failed valve will loose MD the airlock through the skimmer


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[Catanzaro]

Slamming a plug in pump, to compensate for a failed valve will loose MD the airlock through the skimmer


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The plug is behind the shut off valve of the MD only as secondary precaution and only will work if skimmers can be isolated and closed off from the MD. Of course, if one valve for both skimmers and MD, then the plug does not work.

 

[bfang711]

Catanzaro,

One thing I don't quite understand. Why would I see small air bubbles if the valve is leaking? What I thought was, the air in the "air lock" will leak from the suction side of the pump (if I don't plug that end.) and the water will get in and replace the air and fill the whole pipe with water again. So I won't see anything at all from the main drain in the pool. no? Can you explain in a little bit detail why this won't be the case?

thank you very much.

 

[pookiesunshine]

Catanzaro,

One thing I don't quite understand. Why would I see small air bubbles if the valve is leaking? What I thought was, the air in the "air lock" will leak from the suction side of the pump (if I don't plug that end.) and the water will get in and replace the air and fill the whole pipe with water again. So I won't see anything at all from the main drain in the pool. no? .........

my thoughts exactly.

 

[samt]

The only thing you can do is put a rubber plug where the pump was hooked up, wire the valve handle so someone can't turn it and break your air lock. You won't be able to see an air leak.

You can check and see if the rubber plug is leaking with soapy water .

 

[Catanzaro]

Catanzaro,

One thing I don't quite understand. Why would I see small air bubbles if the valve is leaking? What I thought was, the air in the "air lock" will leak from the suction side of the pump (if I don't plug that end.) and the water will get in and replace the air and fill the whole pipe with water again. So I won't see anything at all from the main drain in the pool. no? Can you explain in a little bit detail why this won't be the case? thank you very much.

Please note that this is not from experience. I have a friend who has been in the industry for 20+ years. He closed one of my friends pool as I did not want to touch it (too many leaky valves, etc.) and he told me the "air lock" in the main drain will not hold as there are bubbles in the deep end (leaking out). I was there and could visibly see this with my eyes. The other pools and my own pool do not produce any tiny bubbles at the main drain. This pool was different. It is like using the threaded plugs on the returns and you can see tiny bubbles coming out, which is not 100% sealed.

He is the one who also told me to put a black rubber plug in my system past the valve in the event of a failure. My experience with these 2 items is based on his 20+ years experience and what he told me. Hopefully, he knows what he is doing as he has been closing pools for that long. If not, then if someone had a faulty valve at the pump, it would be quite difficult to diagnose especially if the air leak was small.

It seems logical. If you push water through the piping of the main drain until the water is below the frost line, close the valve, the air is locked from that point up to the valve. If the air does not hold, and water is filling up in the piping back to the pump, could the water at the main drain not create tiny bubbles? If not, then I was misinformed. I would be curious to know if anyone in a very cold state ever experience damage to the main drain (because of freezing) due to a faulty shut off valve. It is bound to happen sooner or later.

 

[Catanzaro]

Below please find pictures of the Jandy Valve that has been rotated and closed towards the main drain. Additionally, the black plug is in the pump basket. The first valve is already closed before blowing out the main drain. Once the MD is blown out, I quickly close off the valve, shut off the Cyclone and then quickly put in the black rubber plug. This is what I was told to do years ago from the guy who closed the pool. Hopefully, these are not extra steps that do not work.

 

[samt]

^^ That's basically what I do except I remove the pump and store it in the basement. The plug goes where the pump attached.

 

[Catanzaro]

^^ That's basically what I do except I remove the pump and store it in the basement. The plug goes where the pump attached.

Sam:

You still have a shut off valve, or do you just plug the line? If so, this means that you have shut off valve and plug the line like I do. How big is the plug? I am assuming you bring in the whole pump, including the pump housing. I can not imagine taking the whole thing apart. My pump stays outside.

 

[samt]

Sam:

You still have a shut off valve, or do you just plug the line? If so, this means that you have shut off valve and plug the line like I do. How big is the plug? I am assuming you bring in the whole pump, including the pump housing. I can not imagine taking the whole thing apart. My pump stays outside.

Yea I have a valve for the skimmer and MD lines. I don't remember the size plug, it is a different size than my return plugs.
My pump has two unions that I can unscrew and bring the whole pump inside with. I can undo the pump in 3 min or less with the unions.

It looks the same as yours. With the unions in about the same place as yours. Yours will come off easy also.

 

[Catanzaro]

You have one valve for both skimmer and MD. If the valve fails, the air will travel to the skimmer (correct), even though you plug the line? I am able to shut off the skimmer to the MD and MD and then add another plug. This is what I was referring to. I also called my friend at the pool company and he is super busy as I wish to find out from him and other techs what the story is and how to tell if air is being lost in the MD.

I do not have a chlorinator, but a Frog System that is not in use. Although, I do place 3" tablets 2X yearly to raise CYA. Full force and dissolve in one day. Then I allow the FC to drift back down over the next week or so. Do this in the first week of pool and somewhere around the middle of the season. Always keep my CYA low, between 30-40.

 

[samt]

You have one valve for both skimmer and MD. If the valve fails, the air will travel to the skimmer (correct), even though you plug the line? I am able to shut off the skimmer to the MD and MD and then add another plug. This is what I was referring to. I also called my friend at the pool company and he is super busy as I wish to find out from him and other techs what the story is and how to tell if air is being lost in the MD.

I do not have a chlorinator, but a Frog System that is not in use. Although, I do place 3" tablets 2X yearly to raise CYA. Full force and dissolve in one day. Then I allow the FC to drift back down over the next week or so. Do this in the first week of pool and somewhere around the middle of the season. Always keep my CYA low, between 30-40.

My skimmer boxes are plugged also. So if my valve fails the pipe circuit is all closed with plugs in the returns, skimmers and pipe at the pump. Only an air leak from the plugs will let the pipes fill with water. Right?

 

[Catanzaro]

My skimmer boxes are plugged also. So if my valve fails the pipe circuit is all closed with plugs in the returns, skimmers and pipe at the pump. Only an air leak from the plugs will let the pipes fill with water. Right?

I guess it really depends on how everything is done. I am not concerned about the skimmer lines as IMO most of the water has been removed and this is why I closed the Jandy Valve towards the main drain. Again, my guess is that your system, the valve would fail and air would travel towards the skimmer line (assuming there was room for expansion) because the black plug is still in tact. If there was room for expansion, then possibly water would fill up, but probably not that much to make a difference, freeze and damage anything.

From what I have read, it is the water that freezes underground that causes expansion in soil and this is a big factor in breakage of the piping, roadways, etc. It takes a long cold weather spell to actually do any damage underground. Last year, I filled up a PVC tube 99% of the way with water and left out in the elements and there was no damage. I also have an underground 6" (very shallow) white PVC that comes off the gutter, which this year I will not take apart. I am curious to know if there will any damage as the ground freezes. The only way I can tell is in the spring when the water melts, if the pipe is still full after a few days. If there was any crack in the piping, I would loose the water.

 

[PoolguyinCT]

Those are Pentair valves, rarely fail. If they do router replacement is easy. (You can hear a failed valve hiss) I like to remove the valve handle to prevent tampering... (Im going to recuse myself from these closing threads)


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