i have an ariston micro combi 23 mffi boiler the pressure in system keeps dropping to zero , when i refill system the hot water works great but no heating,the boiler starts to fire up but stops almost immediately, the pump and fan seem to be working fine just no heat to radiators, any ideas what is cause of this?thanks.

IAN, December 2012

Two problem pressure dropping ? There must be leak on pipe line or water loss through pressure relief valve any sign of water out side boiler over flow if yes change over flow valve, no heating ? motor on diverter valve faulty change it

ltd, December 2012