Advice please! My 5 year old Ariston Clas HE 38 gas boiler has been and still is a real pain. In its short life it's had a new PCB, an additional external expansion tank, PRV, then weeping water valves. Now it's losing pressure intermittently. One day 1 bar next several 0.2 bar losses, then 0.5 etc. Have tried plumber who has suggested it may be a central heating leak or possibly heat exchanger. Tested system for 24 hours cold with flow and return isolated at a pressure of 1.5. Opened flow and return and there was no change and shows 1.5 on an open circuit. Will set it down to 1.0 before restarting. Recently the plumber I called in showed me the condensation trap with red coating and lots of tiny bits in the bottom. He said the heat exchanger showed corrosion but not that much. He says it's not worth replacing and to change the boiler but it may not be the cause. Questions Is it normal for the condensation trap to be dirty and the heat exchanger to show some degradation after 5 years? Does the 24 hour test with no loss of pressure give me hope that the central heating pipes are sound ? New boiler is so which make, how much should it cost ? Or do I go for a Leak test company?