Strange plumbing problem - advice needed!

otron

Hi,

I came home this evening after being away for the weekend to find that the mains inlet valve to the cold water tank had very slowly leaked onto the floor. The damage isn’t particularly bad but it shouldn't have happened - I always turn off the water at the mains under the kitchen sink when I go away, and this time was no different.

I had a similar (but more extensive) leak about 8 months ago, when I got back after being away for a few days (again, with the water mains turned off). I tightened the seal at the time and all was well. I’ve have had a towel under the valve since then, ready to catch any leaks but it’s been perfectly dry for the last 8 months. Until tonight that is.

So after I discovered the leak tonight, I put a new towel in the same place and its still bone dry after 4 hours. I didn’t tighten anything, but the problem seems to have gone away now that the mains supply is back!

The water pressure in my apartment is very variable. I think the reason for this is because there is a pump on the ground floor (I’m on the 3rd), which is sometimes active and sometimes not. What seems to be happening is that the pump is cutting out after working for a few weeks, and is only reactivated when the electricity is restored after a power cut - which is what happened recently.

The difference in pressure when the pump is working is huge, and it’s immediately noticeable at the kitchen sink. So much so that when you turn off the tap after having it on full blast, you can hear the pipes judder slightly.

While I have been away many times in the last 8 months and had no problems, I think that this is the only time that I've been away while the pump is working. This obviously implies that the pump is causing this to happen somehow.

This seems very strange - does anyone have any ideas???

I have a theory on what is happening, which is probably to difficult to explain here, and this post is probably long enough!

Another thought is whether it would help if I left the cold tap open the next time I go away?


Anyway, any thoughts or advice much appreciated!!

Corkey123

It sounds as though the stop cock is leaking due to the variable pressure when in the closed positon.

I had a similar problem recently when I needed to turn off the mains to do some work on a storage tank. Pressure does vary during the day due to peaks and troughs in usage. Suggest leaving the stop cock on when you away (I don't understand why you are turning it off anyway) or have it replaced.

otron

I turn it off because Im paranoid after several friends had immersions or washing machines that developed faults when they were away, causing loads of damage ... seems to be not that rare an occurance.

I can imagine the valve having some trouble with variable pressure, but that doesnt explain why this problem only happens when the water mains is turned off(!)..