to answer this i need to know what warms your water if you have a copper tank you will have a water tank feeding it
also and i guarantee this as a plumber of twenty years wc pressure can leadc to overflowing this usually occurs in the eraly hours when mains water pressure forces into tank not being used as people are not using them this causes overflowing but as water is being used by people getting up all over the country this pressure reduses and when people open thier tanks the levels have dropped thus they think tank is okay
but its not . this is very common and most people dont understand it or realise it is possible but its 100 per cent true
how ever i need more info also if you live in a flat some times depending on layout that although coming out your wall might actually be fixed to your niebours pluming sepcially true of house flat conversions there are many flats on my rounds where tanks ar e in common attics let me know ur set up and appliances
bluebird4211
April 2008