my boiler pressure falls after heating is off
i have checked for leaks but ther is none

martin, October 2011

check the prv outside for a puddle of water. can only do this if weather remains dry.
suspect expansion vessel air pressure is low/empty should have 1 bar approx,= 15lbs psi . in without any water pressure applied in the system inflate using a car foot pump check/test with a tyre pressure gauge

wirecutterman, October 2011

Check if pressure relif valve is faulty

Ltd, October 2011