Biasi 24s groaning on ch start up

[spikebmth]

HW works fine, no noise.

When CH comes on, the boiler groans, this noise is varable and lasts for about 30seconds before queitening down to normal.

The noise starts within a second or two, so heat hasn;t built up to be an overheating noise.

any ideas?

 

[spikebmth]

any ideas?

 

[tryitandsee]

One idea.

Does this boiler have filters in the CH flow or return pipes, if so, may need cleaning.

 

[transam]

It probably is heat related ? , it gos quiet after 30 secs because the gas valve starts to modulate down , you can adjust the gas pressure on c.h seperately from H.W , have you tried this ???

 

[spikebmth]

shouldn;t have filters anywhere on the flow & returns!

I will check the gas pressures, i did read somewhere else about a faulty meter governor not supplying enough pressure.

The brown & red gas valve control box was replaced about 12 months ago, and I think the gas valve too.

 

[Agile]

Only a registered engineer should be checking gas pressures.

It sounds to me as if the main heat exchanger is lime scaled up.

You could bypass the problem by range rating the boiler. If you cannot do the job properly just turn the adjustment until the flame is about 1/3 of the full height.

Tony