Here's a cistern riddle for you

[lynnlmwelsh]

We recently moved into a new house (few months ago) had a leak from bathroom into kitchen which caused a damp plaster ceiling. Well ok I van live with that, new ceiling in kitchen was on my to do list as it looks like the worst plasterer in the world done it blindfolded. Also leaky toilet that's fine I was always gonna replace the horrible peach bathroom anyway ( doing it at the moment) but here's the puzzling part the leak only ever happens at night from about 1 in the morning. Never ever during the day in the morning the basin can have maybe 2 pints of water and the leak is a constant drip from the bolt that holds the close coupled cistern to the pan. But during the day nothing not one drop ever. It's a mains fed cistern so could the colder night time water be a factor ? This has happened since December so winter and summer no difference at all always leaks at night not a drop during the day ???? Any ideas I'm puzzled

 

[lynnlmwelsh]

P.s. As I write this I can hear the drip and it has the precision of a Swiss watch 1am start and by 8 there will be nothing right till about 1 am tomorrow.

 

[Terry lambert]

If you put a pressure gauge on your incoming main, you would probably find that when everyone has gone to bed (1am) the pressure creeps up causing the drip, and then in the morning when people Starr using water in your area, the press sure drops back down.

If the problem persists, you could fit a pressure reducing valve to your incoming main

 

[mysteryman]

It still shouldn't drip as described. However, the new bog should be OK.

 

[TonyW2]

If it is dripping out from the cistern contents, then it would not be affected via mains pressure. (That might overcome the inlet valve resistance but should cause the cistern contents to rise and exit via the overflow)

Is there any indication that the cause could be condensation on the rear of the cistern near to a cold wall and the condensate is running along a route to the bolt?

 

[lynnlmwelsh]

That was my initial thought and I started investigating double wall cisterns etc but in the mean time I dried off the slight condensation put a couple of towels around it to catch any condensation and waited for night time. And drip drip drip as usual. No wet towels no noticeable condensation but the usual dripping from the bolt