Noise coming from boiler.

Hi, I have a Worcester Bosch 24i Combi boiler, serviced early this year, and have recently noticed noises from the boiler which sound like air trapped, ie slight banging and knocking.

I have looked at the instructions, and bled all rads, bled the pump from the screw in the front, and released some pressure from the pressure valve then filled back to correct pressure.

The pressure is 1.6 bar cold, and the problem starts soon after turning on the CH, and will disappear when system is warm.

The system is 2 and a half years old, so don't think sludge will be a problem.

If there is any air in the boiler part of the system, shouldn't the auto air vent get rid of this?, I did try to open it a bit and some air did seem to come out, (couldn't be sure though), or could it be faulty? Do you have any ideas?

Thanks,

Rich.

The auto air vent should be left open all the time (close it then open one full turn)

gigz said:

The auto air vent should be left open all the time (close it then open one full turn)

Click to expand...

Thanks for the reply, when I opened it I left it open probably more than 1 turn, can't be sure until I check again.

The pump works ok, could it be dirt in the system from installation, or adding another rad a year ago, and this collects in the boiler area, it seems strange that as soon as the system gets to full temp all is quiet.

Is it worth draining again and flushing through with anything?

Thanks.

I have checked the Auto Air Vent, it is open a full turn, and seems ok.

The pump seems to work as the farthest, and newest rad heats up quickly, noise is only in the boiler as described above, but doesn't always knock loudly, sometimes makes a kettling sound I think, but if its left on for a while the noise stops completely, so its only noisy when heating the water up.

Is it worth completely draining and flushing the system, and using cleaner, if so what type should I use.