my system is an old conventional system boiler fires up and runs ok i was getting a lot of banging noise coming from the boiler i put in some f1 boiler silencer which has stopped the boiler banging but now after a week or so,after about 20 mins running the pipes start knocking and vibrating radiators are getting hot dosent make any difference if i alter the pump speed pump has been stripped and appears to be working ok
i put cleaner and inhibitor last year radiators bled no air came out

not sure how the boiler silencer works guess it may have disloged some crap was thinking maybe the heat exchanger may be clogged with scale and was thinking of trying to take it out and see if i could clean it
any help much appreiciated

My neighbour, a retired plumber, tells me that in the old days when people actually repaired things it was common to unbolt those rods that hold the sections of the heat exchanger together and then rebuild it with new gaskets. I’d have thought that if you did this with a similar attitude to doing a car cylinder head gasket you’d be OK. Ours used to weep water, which would hiss and fizz as it warmed up.

In the end though we decided to go for a new condensing boiler so we sold (with great sadness) our old Land Rover, a money pit, and turned it into a new boiler, which saved us about 30-40% on our gas consumption.

But go and ask on DIYnot.com, they will know better.

thanks thats what i am thinking it has 2 end plates which are bolted on
wether they will be corroded solid is another question

unbolt a main cast iron heat exchanger..GOOD LUCK!! book a new boiler for the next day ‘just’ in case..

I have a 25+ year old cast iron heat exchanger / boiler, no chance of unbolting it as it’s rusted solid.

They tend to fill up with limescale after a while (say 10 years), so over heat and boil water in the heat exchanger. I rejuvenated mine with Fernox DS-40, which is pretty strong stuff, so there is a risk you’ll spring a leak. However, it did wonders for my boiler.

how long did you put the ds-40 in for i awas looking at that

You leave it in for 7 days. Make sure you put a hosepipe on the overflow pipe – mine was spewing rust coloured foam for hours – made a right mess of the wall of the house!

The difference it made was quite amazing, but we’re in a hard water area, so I reckon the heat exchanger was 50% full of limescale!