It's the hose, left of boiler inside, they do become partially blocked. A flush isn't required at all, although they may know that this is blocking and are using the BG get out. Have this changed and the canoe filter checked first before considering a flush.
Having gone a week without hot water and heating I decided last week to proceed with the BG powerflush. They arrived onsite this morning, but realised that some of the sub floor flow / return pipework for the boiler is most likely plastic piping with push fit connectors (he can't see this for sure but assumes it is based on the movement of the copper pipes connected to the boiler) so therefore wont perform the flush due to concerns that these fittings wont be able to withstand the flush pressure during the operation.
Can anyone advise if these push / compression connections would be able to withstand power flush pressure as I fear at this stage that unless I can flush the system (most likely by an independent contractor) I'm going to have ongoing heating and/or hot water problems with heat exchangers becoming blocked etc.
Thank you in advance.