Hydrostatic Relief Valve Leaking?

[alam2p]

It very well could be, any way to confirm? Detaching waste line or checking the end of it? Cut it temporarily and add a union?
If it’s leaking your mpv is the problem. Does the pool only leak when the pump is on? If it’s not mpv you can isolate returns(return everything to spa) vice versa, monitor.

Is it possible for an MPV to leak in the CLOSED position? I can't find any resources online on how MPV's work.

There's a caveat to my success: I only filled it up as much as I can and found that it held water, so at least I could say that it is not a structural issue, and I'm 90% sure I can eliminate it as an issue with my return lines. After a further fill, this morning, I went to check and the water level has dropped just to the mouth of the skimmers and both skimmers are completely dry (as expected as they are tied to the same line)

In my excitement and rush, I did not close off the skimmer valve in the pool room originally because the fill wasn't up until that point yet. I have done that now, and I'm starting to narrow it down to possibly a skimmer line leak (causing it to lose all the water inside the skimmer), or still an MPV/backwash line leak. Prior to all this, I still believe that the water was back flowing through the equipment to wherever the leak is through the return lines.

I'll leave the water level as it is and see what happens. If it stays at this level all day, then at least when I have a leak detection specialist come in, they won't be wasting too much time tracking it down.

 

[Poolbreh]

s it possible for an MPV to leak in the CLOSED position? I can't find any resources online on how MPV's work

Yes if the gasket is bad.

 

[wireform]

Is it possible for an MPV to leak in the CLOSED position? I can't find any resources online on how MPV's work

You can have a damaged spider gasket which can cause all sorts of issues but if the mpv is not set to backwash and your losing water out that line that means the mpv is not holding.

 

[alam2p]

You can have a damaged spider gasket which can cause all sorts of issues but if the mpv is not set to backwash and your losing water out that line that means the mpv is not holding.

Thanks to all replying.

This morning I closed the skimmer valve and filled the skimmer up. By the time I left for work (30 min later), the skimmers were completely dry again. Leads me to think that it’s a skimmer line issue. I’ll plug it up and fill again when I go home to see what happens.

The repair will suck as it’ll involve cutting concrete, but at least the issue is clearer and I’ll save a bit on the leak detection part of the repair.