Are there any plumbers on here?
My heating system will need replacing in a few years time; in the meantime I was looking at getting someone to powerflush the radiator/ pipes.
I don't think it's ever been done before on the house. I live in a hard water area, and was wondering if it'll have much effect/reduce strain on the boiler/make it more efficient - or if it is just a service designed to part fools from their money?
Advice/mockery for considering such an idea welcomed.
Hard water should have a minimal effect. The heating system should be filled once and should only take in more water if there's a leak. It's more likely to scale up the secondary side (domestic hot water) of a combi plate heat exchanger.
Most boiler manufacturers specify flushing the system out for a new boiler or you'd invalidate the guarantee.
The black magnetite sludge you find in a lot of UK heating systems is the corrosion products from the inner surfaces of the steel radiators reacted with oxygen. You could reasonably expect to find it only if air was getting in; dissolved in make-up water due to a leak, pumping over, etc.. But no, there's a catch.
If you have two different metals (e.g., copper pipes & steel rads) immersed in a suitable acidic electrolyte, you get a Galvanic corrosion cell and the less noble metal (steel in this case) corrodes. Car batteries are an example. If you're getting Galvanic/bi-mettalic corrosion in your heating system, then you'll get H2 & O2 released by electrolysis.
The O2 produces corrosion, the H2 collects in your radiators. If you're not getting cold spots regularly at the top of your rads, and find you need to vent the flammable gas regularly, that's probably not happening.
Galvanic corrosion & black sludge occurs a lot in the UK because plumbers use active soldering flux (Powerflo, etc) which produces acidic residues and that turns your water into a conductive electrolyte. It needs to be neutralised & flushed out or, better still, not used. It's not usually flushed out because the problems only appear in 5/10 years time when the installers are long gone.
French plumbers don't solder heating pipes, they braze them. They don't use acidic flux. They use a brazing alloy with phosphorus that doesn't need flux. There is no powerflushing industry in France; rien du tout. They don't get black sludge in their heating systems.