i have a potterton puma 80 combi boiler and the hot water is working but the central heating is not. When i turn on the heating the boiler fires up but then steam comes out of a vent at the top of the boiler and it dies down

lee ratcliff, January 2006

your diverter valve is gone mate, best thing to do is get a corgi regetered engineer in to fix it, but u could do it yourself, it is not a hard job to do if u know a little about boilers

wakhar, April 2007

this is a blockage in the system but a blockage can be anything from a stuck diverter valve, siezed pump, isolation valves on the bottom of the boiler closed , blocked filters etc as a starting point i would check your pump they have a big screw located on the front of the pump remove this and turn the spindle inside with a screwdriver vif it is jammed it will free the pump

mike, January 2006