Boiler advice

[Dave Plowman (News)]

OK

No - but is it working? Is the pump actually running when the kettling occurs?

[charles]

yes - I can hear it.

Since pouring in some system cleaning fluid late yesterday afternoon, the system has been quiet. Maybe that's all it needed.

[cynic]

System restorer can have magical results. I suspect your system has slowly developed a sludge problem which has finally restricted the flow through the radiator circuits to critical level. Lockshield valves being adjusted to regulate flow to balance the heat distribution are often where this manifests itself. While your cleanser is still in the system I would tackle each one in turn, starting with the radiator you mentioned as showing a problem, turn it fully closed noting exactly how many turns or part turns it requires, then open it up fully and allow high flow through that radiator and pipes for about half a day and restore the lockshield to its original setting. Move on to the next radiator and repeat. On completion of the exercise drain down from hot, refill and dose with fresh inhibitor. I prefer Sentinel to Fernox but ymmv

[Dave Plowman (News)]

Don't see how if it's always had inhibitor - which I'd guess Charles has been careful with.

[Stephen]

That sounds like one of two causes. A faulty circulation or you have sludge build up in the boiler.

If the first, check power to the pump, if there is power, replace pump. If there is no power then suspect a faulty microswitch in one of your motorised valves.

If the latter, you can buy sludge remover and power flushing gear to flush the boiler with.....

Stephen.

[cynic]

SNIP

The use of inhibitor is supposed to prevent corrosion but in an old system which has developed the odd pinhole allowing air ingress the useful content can be "consumed" and leave the system prone to oxidation and/or biological growth in the head tank which can be drawn into the system following a partial or full draindown for such as a rad valve change. Its a creeping disease which becomes evident when it passes a certain point.

[Dave Plowman (News)]

Older systems often have an open header tank. And given it allows for expansion, some air will always be present in the circulating water. If the inhibitor has been kept up to strength, virtually no corrosion should take place. Of course if the system is leaking badly so constantly taking on fresh water - or pumping over all the time - things can be different.