Blowing Out Main Drain and Air Lock Question

[rscam]

Hi everyone. New house has existing pool. Got thru the season great thanks to you guys, now time to close for winter. Plan to do myself and have question about the main drain. I plan to use a compressor to blow out the main drain and then air lock it with the 3 way valve that is in place (Hayward Dial-A-Flo - see picture). The left port leads to the main drain, the right port to my two skimmers and the bottom port to my pump inlet. Seems straight forward except for my faith in the Valve to reliably hold the air lock. It seems to me that I would have no way of knowing if the valve has a tiny leak and slowly lets the water rise up above the frost line over the course of the winter. Is there any way to verify that its really holding all winter? Any help would be appreciated.

Thanks

Ron

 

[Catanzaro]

Seems straight forward except for my faith in the Valve to reliably hold the air lock. It seems to me that I would have no way of knowing if the valve has a tiny leak and slowly lets the water rise up above the frost line over the course of the winter. Is there any way to verify that its really holding all winter? Any help would be appreciated.

You will hear the valve hissing, and/or the main drain continue to produce air bubbles at the bottom if there is a problem. You can also open up the pump basket housing and place a black winter plug in there as a secondary, which I have been told by members in the business that it works (I have no idea). But if the valve fails, there is a small gap between shut off and plug. I have my main drain right off the pump, and to the right is the skimmer(s) valve. During the winter, I turn the skimmer valve towards the main drain as they are cleared first with little to no water in them, (which now creates a lock one way to the main drain and also to both the skimmers), and then the valve for the main drain creates another lock, plus the plug. Kind of 3 separate shut off areas in one set up. I also have to remember to put everything back or the system will run dry upon start up. You should be fine.

 

[rscam]

Thank you. I bring my pump in for winter, I suppose I could put the black plug directly into the valve port after pump detached?

Follow up questions:

If the valve fails, wont it leak directly out of the valve to atmosphere? If that's the case, the extra plug wouldnt do anything right?

I was thinking, maybe I can set the compressor to a low pressure output (couple psi?) shut the valve and apply pressure and see if it holds? Not sure if I risk damaging valve though?

Thanks for the help

Ron

 

[Catanzaro]

Ron:

Do not overthink this one. If you can place a plug right behind the same run, if the valve fails it will hold. If you have them tied to the skimmers, it may move towards there. I would not worry too much. Please upload pictures of your description because you bring pump in for the winter. Only see the shut off valve.

 

[Pool_Medic]

Trying to keep the air in the main drain lines is nonsense. By blowing it out, you have moved all the water down that line. Let the line gravity feed back full of water and it will fill from the drain until level with the pool water. Once freezing temps hit, anywater in that line has a place to grow as it freezes and expands. Either up into the air filled section or down to the water filled section.

Plugging that line can actually result in damage as the resulting pressure from the water keeps trying to push that air out. The closing thread should say this and any main drain line that goes back to the pump shouldn’t be plugged. Any main drain line that is plumbed to the skimmer should have a four ft piece of foam rope inserted then plugged. That is the proper process for extreme weather areas such as mine.

 

[JamesW]

If you can get the main drain to blow and then close the valve to trap the air it should prevent the water from refilling the line.

Basically like blowing into a straw in a drink and then putting your finger over the end of the straw to block the end. The air is trapped and the water stays out.

The pressure is only 3.5 psi, so no problem at all.

Once the valve is closed, you can plug the line with a plug in case the valve leaks.

If the valve leaks and the line is plugged, air can go towards the skimmer line, but the skimmers should be blown and plugged before the main drain, so air shouldn't be able to escape that way.

The only other way for air to escape is through the valve itself if it leaks. You should be able to hear any air escaping. You can use a soap solution to check for air leaks.