Descaling a combi boiler

[Ant]

Does anyone know of an easy(ish) way to decale a combi boiler - domestic hot water - not central heating side. I assume to do it in situ would mean draining the hot water circuit and somehow backfilling with descaler/water cocktail and the flushing out. Has anyone tried this or similar. I live in a hard water area so I am concerned the boiler is not fully efficient at present as it has been in several years. Any advice would be helpful.

 

[breezer]

As far as i know you can't do that (I hope i am wrong) because on a combi boiler the hot water comes directly from the mains so there is no where to put a descaler in.

As i said i hope i am wrong because i had to have the heat exchanger changed due to scale build up, it was a well over £150. the boiler is about 7 years old.