Have got 12 radiators running off a Grant oil burner which is about fifteen years old, whilst it is balanced properly it takes about 30 minutes to heat up and some rads are hotter than other. Couple of years ago I put Fernox cleaner and inhibitor through it but I have a feeling that there may be some sludge. Powerflushing is going to cost about £400 and the plumber assures me it will remove everything but I am thinking is it a waste of money and would I be better taking them of the wall one by one and back flushing.

Powerflushing costs the price of a length of hosepipe and a jubilee clip. It’s a piece of piss to do yourself.

A lot of boiler manufacturers Including Worcester Bosch insist upon it for warranty on new boiler to be valid.

A lot of boiler manufacturers Including Worcester Bosch insist upon it for warranty on new boiler to be valid.

was the only reason I had mine done.

plus, a lot of old sludge came out so I guess it at least stopped it getting circulated round to the new boiler when they refilled it.

My heating was patchy even after balancing, 17 rads on two zones and water heating.
Fitted one of these after draining the system,

http://www.screwfix.com/p/sentinel-eliminator-system-filter/77150

and filled back up with two tubs of this:-

http://www.screwfix.com/p/sentinel-x800-heavy-duty-sludge-remover-1ltr/84921

Now after a few weeks the sludge/metal fragments have stopped coming out of the filter when I drain it and the boiler has been turned down to just above half way on the stat.
The hot water has also been turned down on the tank, as it was getting too hot.
All the rads can be on at once and are all properly hot together.
Found tapping the rads with a rubber hammer helped dislodge the sludge, with the pump on top speed and the valves fully open.

£130 in total and will drain it next month and re-fill with inhibitor.

Older systems with massive cast iron heat exchangers are quite happy pumping rusty nails around them. Modern heat exchangers are much more fragile and get easily blocked, hence the need to power flush everything.

I had a solder ball which took about an hour to do a complete loop of my system, you could hear it going through the pump roughly every hour…..

Fitted central heating 15 years ago, never used inhibitor, drained system a few times water looked clean enough to drink.
Still on original boiler.