Our hot water pump went recently and the bloke who replaced it said we had a lot of gunk in the system. The radiators still get hot all over but there is a lot of black sludge about. He quoted £450 to clean the system out with some sort of acid which I understand from a plumber friend is a reasonable price for this labour intensive job. However a few years ago when we had the boiler replaced the bloke who did it said there was a problem with our radiators and he couldn't degunk???
I fancy having a go at cleaning the system out myself. I want to know how to go about it. I understand you can buy stuff at the local DIY store for this job but how do I go about things.
Where do I put the stuff in? Expansion tank??
What do I need to turn off to drain the system? Expansion tank fill valve how about the cold water tank fill valve?
I will be draining the system from a valve on a radiator just by the front door, do I need to drain the hot water system aswell.
I presume I need to turn the boiler off throughout the drain?
Should I expect leaks from previously gunked up joins?
Genral advice aprreciated. Thanks in advance.