Odd ball valve behavior -- letting pressure through slowly without obvious leak otherwise

chrismarcellino

I had an unexpected thing occur when I was filling my system. As our water is quite hard, I filled with tap water through a demineralizing filter to avoid using softened water (which my continuous fill valve is connected to) using this side hole port on the Webstone expansion tank replacement valve (see pic).

What I noticed is that if I have the tap pressure attached to this valve, even if this valve is closed, the pressure keeps slowly rising to tap pressure (obviously I stop it before the T&P leaks at 30 psi.) If I shut off the tap hose valve upstream of the demineralizing filter, the increasing pressure stops so I don't think it is a conincidence. The other autofill valve works fine and this happens regardless of whether that is shut off.

So, it appears that at least at tap pressure, this expansion tank hose valve allows a slight amount of water through. Oddly, when I unhook the hose with the valve off, I do not see a leak and don't see a loss of pressure. Something about seeing 70 psi keeps this valve from sealing tight? Has anyone seen this before? I assume there is no easy repair in place like tightening the stem--and it doesn't really matter since doesn't appear to be a problem in normal use?

Thanks,
Chris

Jamie Hall

Not uncommon fr a slightly worn seal or seat — or any slightly flexible connection, for that matter — to leak in one direction, but not in the other.