Andy Hall wrote:


Another one along these lines is leaking spindles on radiator valves.
A small leak may only be happening when the system is hot and of an
amount that it is evaporated by the heat without showing very much or at
all from the caps. Try going around and removing each cap for a look.
Replace any radiator valves showing signs of leaking with new, good
quality ones such as Pegler. Spindles of motorised valves are another
candidate.

Hi Andy. Yes, this is a conclusion I have come to, hence my current
project to introduce anti-leak chemical into the system. But I want to
de-sludge it all first.

Pressure relief valve is certainly a favourite. If this is leaking,
then a replacement is the solution since they are impossible to repair
reliably.

See my reply to EricP.

Concerning a thorough system clean; a better approach, which would not
have issues with different materials and use of chemicals, would be to
remove each radiator in turn, take it outside and flush it with a
pressure washer or hose on the mains. While the radiator is removed,
flush system water out at the radiator position from the valves.
This means that crud is flushed out and not around the system and is
much more effective than circulating an acid cleaner.
Care, because sludgy water is an indellible dye. Small sandwich bags
rubber banded over radiator tails is a good plan while moving them around.

Gulp. I did all that when I put the new boiler in in 1997. I was a fit
young thing then! Don't want to go through all that again in a hurry,
especially as it's winter still and I was hoping a chemical treatment
would suffice for my purposes. If I was replacing the boiler, then I
would replace all the remaining steel rads and valves too. But I hope
that won't be necessary for at least another 6 - 12 months, as I have
several other major projects on hand at present to occupy me with.

An alternative that would be better than adding a cleaner and
circulating would be to rent a pressure flushing machine and use that to
power flush the system.

'Tis an idea. Hadn't thought of that. But I liked the fact that the DS40
states it *would* return the rads and pipework to bare metal condition. :-s