Noisy system boiler

[mbrad]

I've got an ideal system 30 fitted at home which has started to make what I can best describe as a hissing noise once the boiler reaches temperature and knocks off. It has a vertical flue, 2 90's and 2 short extension pieces. There are 2 towel rads ona seperate zone and there is an automatic bypass fitted. Any help would be great as my elderly neighbour has complained its waking her up in the morning.
Many thanks

 

[Agile]

The important aspect to consider is if it makes the noise when the burner is on or after it goes off.

I would guess that its while the burner is on and that it is particularly coming out of the flue.

Then I would guess that it is a combustion setting problem.

Lastly I would guess that either you don't bother to get the boiler serviced or whoever does service it does not correctly set the combustion parameters.

So how many of my guesses do you think might be right?

Many of the boiler makers do not allow 90 degree bends thus creating a horizontal section with a vertical flue although I have not checked the Ideal instructions in this respect. But regardless I don't think that it is relevant to your current problem.

Tony

 

[mbrad]

The noise starts as soon as the burner goes off, it continues even when the display says "0". The boiler is 4 months old and the manufacturers instructions state that the combustion is preset at the factory.
Ideal allow the 90 bends for the flue, is detailed in the manufacturers instructions also. I hope that's enough information.
Thanks again