Everytime the timer for heating goes off the heating won't come back on unless I top up the boiler. I can't see any leaks and the radiators are piping hot when heating is on. The pressure needle drops but as soon as I top up the water boiler comes straight on and works fine. Also sometimes when the boiler hasn't been used it sounds like groaning spaceship landing - when you turn tap on it stops!

Heather, February 2009

Heather

You need to find out where the water is leaking out of the central heating water system. This is usually a closed system which has to be maintained within certain pressure limits. The boiler will not fire up if there is insufficent pressure in the central heating water circuit. All you are doing is building up the pressure again so that it will. As soon as the pressure drops too much the boiler will cut out again.

Does any water come out of the overflow pipe that sticks out of the external wall behind the boiler? If so then you probably have dirt in the overpressure 'safety valve' or it is not sealing properly because the valve or its 'seat' are worn or damaged. Sometimes a quick twist of the red cap on the 'safety valve' will blast the dirt out of the valve seat (don't try this if water is not dripping from the overflow pipe otherwise you could actually lodge some dirt in it). The only other place to look for the leak is probably under the floorboards. Until you find and fix the leak you will have to keep topping it up.

Good Luck!

Mike

Mike, February 2009