Replacing pvc ball valves

[Quadman2004]

My ball valves on my return pipe and drain pipe into my sump are frozen and can't turn them at all. I need to replace them. My questions are
Is there any way to loosen these at all to avoid replacing them?
What's the best way to replace them?
Do I need to empty water from tank first?

 

[JohnK]

Assuming that everything is cemented, you probably need to cut the valves out and replace them. Figure you cut the valves, leaving at least a couple of inches of clean pipe on either end. Attach a new valve to the pipe on one side, then use a couple of inches of new pipe and a coupling and you're good to go.

 

[Roccus]

use true union ball valves... that way, in the future they can be removed without having to glue them....

 

[Puff Daddy]

If you don't have a PVC pipe cutter, now is the time to grab one. It will make the job a lot cleaner and easier.

 

[JohnK]

Very good point about using true union valves, I meant to include that in my reply. If you really want to do it right get two for every one you need, that way you can quickly swap them out for a vinegar soaks.

PVC cutter, huh, What do you have against Hack saws, blood, sweat and Tears

 

[Roccus]

getting two of the same TU ball valves is a good Idea because manufacturers have a nasty habit of changing designs every few years...

I'll add, that I get them with FNPT and a male adapter so in the case I do need to change one out in the future I can unthread it and thread on another..no gluing or re aligning my plumbing...
depending on the size of the PVC cutter they can be pricey, my 1 1/2 cutter was around $100... but I use mine for work as well... ad still find myself reaching for the sawzall anyway...

 

[Quadman2004]

All great info and advice guys! My valves are stuck in the open position. This might be a stupid question but when I cut them out what happens to the water in the tank? If I drain just the overflow will that work and avoid a flood?

 

[JohnK]

The water will all fall out on the floor

As long as your overflow(s) don't leak then just the water in the overflow(s) will drain out. If you are worried about leakage, make a temporary plug for the bulkhead(s) inside the overflow(s). To do this, assuming they are slip bulheads, get a section of that sized PVC pipe and a PVC cap. Install that in place of the existing durosos, stand pipes or whaterver is in there, but don't cement anything. If those plugs leak it will only be the slightest bit, then you remove them when the valves are installed and the cement has had a bit of time to dry. (if you do the plug thing, make sure to lightly sand any sharp edges off the plug pipe so it doesn't fit overly tightly into the bulkheads, and don't install with force, just wiggle into place)

Also, when cutting out the stuck valves, be very aware of any twisting / torquing pressure you might be applying to the bulkheads and by extension the tank glass. Your plumbing often has a lot of leverage, so if you don't keep this in mind it can be easy to crack a bulkead, or worse the tank itself.

 

[Quadman2004]

Thanks for the advice John. I will keep all of it in mind when I replace them.