vibration noise when boiler switches off

Hi all,

I have a new CH system, combi boiler (Ferroli Optimax 31C). It was installed in Sept 07 by a local installer (fully corgi registered).

When the heating comes on it all works fine. However when the heating goes off, there is a 2 second series of vibration noises. Probably about 5 to 10 thumps in total, a deep bass'y noise. It almost sounds as if its the noise of the pump spinning down. A little bit like water hammer. I can't actually hear it at the boiler location (loft) but can in the bathroom below and sometimes it reverbs through other rads in the house too.

Recently, I have noticed if I am in the bathroom below the boiler (in the loft directly above), that the boiler seems to be getting noisier during normal operation. Its like a hissing / humming kind of flow noise. I don't know if this is due to it working harder as its colder at the moment. Having checked the boiler a couple of times, it is running at its maximum flow temp of 95 deg at the moment.

Should I call out the Ferroli engineer, or the installer, or neither?

Cheers

Installer, after turning boiler off, 95C is way too high!

The noise is being caused by the excess heat left in boiler on shut down you sure 95 most boilers go to 82 ish on normal working and over heats trip around 90 give or take couple of degrees

Hi,

Many thanks for your replies. However the manual states that 95 is the max working temp. The max setpoint is 90 which is adjustable.

I could try setting it lower? 85?

Your point about excess heat - the pump is supposed to overrun to prevent this.


Cheers

Hi all,

I have had a good test session with the boiler tonight and can offer the following additonal information.

1. The noise appears on start up and shut down.

2. The noise can be heard eminating from the boiler (in loft), but seems louder in the house below due to resonance through the pipes presumably.

3. If I run the cold water, the noise appears. Its as if the boiler is detecting a pressure drop on the cold and shutting down. However it starts back up immediately even if the cold is still running.


I have got the installer coming round tomorrow night so will feedback his opinions.

Cheers

Hi all,

Have had the installer round, he opened the case and had a nose around. He said it was the diverter valve opening and closing and making a vibrating sound when it does so.

I have phoned Ferroli to arrange for an engineer to come out (under warrenty). Would you all class this as a manufacturing fault? It doesn't seem to effect the operation of the boiler itself but is it right for these components to generate vibrating / grinding noises when they operate?

Cheers

danlightbulb said:

Hi all,

Have had the installer round, he opened the case and had a nose around. He said it was the diverter valve opening and closing and making a vibrating sound when it does so.

I have phoned Ferroli to arrange for an engineer to come out (under warrenty). Would you all class this as a manufacturing fault? It doesn't seem to effect the operation of the boiler itself but is it right for these components to generate vibrating / grinding noises when they operate?

Cheers

Click to expand...

Hi Dan,

I know its 2 years on but I have exactly the same problem with noise on start up and switch off for about 18 months now and its driving us mad. Engineers been out 4 times,not much help, seems it is just a bad design fault. Did you come to any solution? Searched the internet for ages until I found your problem which is exactley the same as mine.

Cheers