The needle on my vaillaint boiler is displaying a reading almost in the red zone (number 3) and we are beginning to worry. There has also been an effect on the toilet probably due to this problem, as there is now a hissing noise coming from the pipe inside, and the flush water is now filling up very slowly. We have tried everything we know of, but would appreciate anyone who knows what may be causing this problem to help.

FalconArc, January 2006

hi,
sounds like the filling loop is not shut off properly (the bit used to top up the pressure). check that this is fully off (see instruction manual). if the pressure keeps rising and the filling loop is fully off, then the dhw heat exchanger is faulty. nothing about the boiler will have an effect on the toilet! that will be the ball valve in the cistern needing repair or replacement.
in either case(s) you need a corgi boiler repairer or plumber for the toilet, if you cant resolve the boiler by just shutting off the filling loop

graham, January 2006