I have gas central heating served by a valiant boiler.

[chris watkins]

If it was the flush valve would not the float valve be refilling all the time guy's (worth checking valves are off & then remove the filling loop if you have a combi boiler, Tina)

 

[TBServices]

If it was the flush valve would not the float valve be refilling all the time guy's (worth checking valves are off & then remove the filling loop if you have a combi boiler, Tina)

No. Because: A. The toilet isn't being flushed at night therefore a very slow fill into cistern will only lead to overflowing at night, and B. nighttime water pressure is higher. There's 2 possible reasons.

Really though its going to be tough to diagnose if you don't have a plumber who will come out at midnight. May be some trial and error but I'd start with toilet.

 

[DirksPlumbing]

If it was the flush valve would not the float valve be refilling all the time guy's (worth checking valves are off & then remove the filling loop if you have a combi boiler, Tina)

Not necessary, if it is a silent fill valve it will behave like this. But these would not bother with the pressure. Strange though.