I am NOT a competent DIY-er, so have had a plumber round to check noisy CH system - he's identified dodgy pipework (which fits with manufacturer's opinion). He also said that we should get the system flushed (cold patches in rads, frequent air locks): I have seen the correspondence on this already, so am loathe to fork out Â£350-500. I wonder, would it be cheaper/better to get the radiators replaced (they are at least 16 years old - 5 of them) or to go for cleaning the system? Or both? Even if we don't go for a power flush, we'd probably need a plumber to do this, being scared to death of making a mess of it ourselves!
I would remove radiators and flush out.
Flush pipework a couple of times, refit radiators and refill - run heating and flush when hot.
Then refill adding system cleanser or sludge remover and run for a week or so.
Then you can drain and flush a few times, fit the new radiators (if you want) and add inhibitors.
Without the price of the radiators it will cost around about Â£30 for the chemicals and whatever in labour. Not a bad little DIY job, if you're still not sure -get a plumber but they'd probably rather power flush it.
No-one in the family with a bit DIY knowledge that'll help.