DIY Doctor UK DIY Forums

Had a complete heating system installed in september 1998 consisting of 6 radiators (Previously solid fuel)

The boiler is a worcester bosch 24i that has not had any major problems, apart from a leaking auto vent valve & air pressure switch faulty (Both of which were replaced).

Last few months there is a noise from the boiler that occurs when the heating comes on, but not right away, only when the system starts to get warmed up (after about 5 to 10 minutes of running).

After a few minutes this noise stops & doesnt reoccur untill the system is cooled down, then the same thing happens again.

I noticed that if i turn the roomstat down ( enough to cut the gas supply) the noise stops immediately.

Thinking it may be an obstruction\sludge in the heat exchanger, i put some of this cleaner in to the system via a radiator

http://www.awin1.com/awclick.php?mid=15 ... nvt/159831

It states that it should be left in for around 28 days. I also bought some of this protector to put in after i flush out the cleaner.

http://www.awin1.com/awclick.php?mid=15 ... nvt/159830.

If it is kettling because of scale build up, would it not make this noise all the time the heating is on & not just at a certain point in the heating process?

Thank you.[/url]

Would air trapped in the ch circuit cause this type of noise?

Yes it's more likely to be air, as if it was kettling the noise would get louder the hotter the system gets until the burner extinguishes.

It could also be a problem with modulation, it could be staying at high rate for longer than it should, this could just be a sensor fault or a pcb fault.


htg

Thanks htg. Am hoping it is air. The system seldom looses pressure & maybe once a year i have to top it up to the 1 bar mark, but tell you what, it can be a bugger to get the air out.... & of course the more you bleed the system the more go have to keep topping it up.

Will leave the flush in for the specified time then will drain\flush it a couple of times before putting the inhibitor in. Then see what happens.

Many thanks again for the reply.