In November my boiler began leaking water and the engineer fixed this simply enough - release valve on top of the hot water tank but said diaphram in the red expansion tank had failed causing pressure to get high. Humm...seemed ok to me before. The oil then ran out but with a delivery and a few resets the system was working fine. Tank now replaced so all back to normal. The day after the tank was refitted the boiler locked out. Humm...No matter how many times it is reset it won't fire up and locks out. Most of the boiler has been replaced last year so either it is not igniting or something has been tampered with. I am concerned at another call out as the landlord is annoyed with having repairs done but hey it's an old boiler. Got a new lease in January which omits his being responsible for the central heating so am looking for advice.