hi, had my boiler serviced and engineer has diagnosed a drop in pressure of gas between inlet and boiler since he last serviced it. boiler is in full working order. he tested presure of gas coming in to house which is fine. he suspects either blockage in the pipe or damage to the pipe(which he said is unlikley) the pipe is from understairs to outside the house(under floor and driveway) up wall and in to back of boiler, he said options are to have a new pipe between under stairs and boiler(routed internally) or to dig up and look at existing pipe. does this solution sound right? can a pipe be unblocked or checked in a similar way to drains? how would a pipe get blocked as it is never open either end? boiler works fine, he said there is no danger but boiler will not function to its best and this will be more noticeable trying to heat water in the winter which I can verify. sorry for long post!!