Replacing union ball valves with diverters


Active member
Aug 20, 2020
Poughkeepsie, NY
My pool installer put in these three cheap union ball valves. One of them is an Astral 06621 and the other two are similar/generic. They're all different brands but the fittings look the same. With my pad redo this spring, I'd like to replace these with long-lasting diverter valves. Jandy Neverlube seems popular around here. But as you can see, there isn't a lot of room to cut out these fittings and install new ones.

Question 1: This union fitting. Look at the top piece in the first photo, or the rightmost piece in the last photo. Is there a matched coupling that I can use to turn it into a straight union instead of a union valve? For example: the Hayward SP14952S is a straight union, but the threading is different than on these. So if I remove the valve, is there something I can mate with the existing piece, and connect the diverter to that, rather than cutting these out?

Question 2: My pool pad is downhill from the pool, so whenever a valve is open, gravity is going to do its thing. The jets and the skimmer are plugged for the winter, but for the main drain line... it's always going to be under pressure. Not a lot of pressure (the main drain valve is only about 6" below the waterline) but some. Assuming there's a coupling and it can all be done by screwing/unscrewing: has anybody ever tried replacing one of these under pressure? I'm thinking: open both valves, unscrew the existing one, screw on the new one while open, and then close it... and hopefully not lose too much water in the process. But I'm looking for a sanity check on this.

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Gold Supporter
May 20, 2020
Katy TX
Pool Size
Liquid Chlorine
I have read about a device that you can insert into your PVC to create a new seal - I think it is used if you have a damaged return jet. It is not so much the pressure but the volume of flow through a 1 1/2" pipe is a lot when it is wide open so you stand to lose a lot of water in a short time. Not sure this would even work if you could force this barrier in plus it has to fit through your existing valve ID. Your logic is OK on the switch out of the valves to keep both open but I do think it is a lot of flow. Is there any way to put a cover on your main drain to slow down or partially seal it so you only have to deal with the volume in the pipe and not what volume is in the pool? Probably best to do some more research on this or see what others provide ideas on.
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