Neighbour's flue sounds like jet engine

[emzedcee]

All the Kestons have very flexible flue systems made up of fairly inexpensive muPVC pipe (though strange to note it is not sold in the Old Trafford Souvenir shop, just as well or it wouldn't be inexpensive ) It is also good to know that it's never been called Chelsea pipe for the same reasons......

....back to the flue, if you wanted to offer to pay to move the flue pipes I suggest you approach the neighbour with this solution before setting the hounds on him/her and cause conflict, he may not accept your kind offer after a row! Directing the flue vertically, or through another wall may reduce the noise considerably.

Thanks for your very contructive suggestions. I've now had a closer look at the pipework and it seems that the flue already goes vertically up the wall. In fact the noise appears to be coming from another pipe that sticks out of the wall at just above head height - is this an air intake? Any further thoughts gratefully accepted. Cheers.

 

[Agile]

The air intake should be pointed downwards or have a kind of capped head on it to stop water entering.

It should not just point out horizontally!

If its already pointing downwards and still making a noise then it would not be difficult for me to produce a silencer.

Having said that, I would not expect the noise level at 1 m to exceed 60 dBA and thats about normal for a boiler flue.

Tony

 

[htgeng]

Almost all the C25's I installed had these sort of noise problems, even when correctly setup with a FGA.

Keston denied any malfunction and the engineer blocked off most of the internal air intake tube with a piece of plastic. This did seem to reduce the noise to acceptable levels, but hardly seemed a 'proper' solution.

I would approach the neighbour and ask them to get Keston to service it. Its in their interest anyway as if C25s are not serviced regularly, they are unlikely to have a long lifespan!

 

[croydoncorgi]

There's some pretty off-the-wall advice and comment flying around here!
It's not even clearly established what model the boiler is!

If it's a K130 or K170, then they ARE noisy. The premix blower is ENORMOUS and if the bearings are naff, it will become even noisier.

The idea of 'blocking off part of the air intake' sounds unlikely (actually, unbelievably stupid and hardly likely to be done by a 'Keston engineer'!). It would mess up the gas mixture in the burner and would probably make little difference to the noise level.

Moving the position of the intake sounds like the best and simplest solution. Apart from anything else, making the pipe longer would reduce the noise anyway

 

[emzedcee]

Dear all

Thanks to those of you who posted constructive suggestions in response to my cry for help. I only hope my neighbour will take them on board. My husband and nine month old son are also very grateful!

Here's to a quiet life!

emzedcee

 

[htgeng]

The idea of 'blocking off part of the air intake' sounds unlikely (actually, unbelievably stupid and hardly likely to be done by a 'Keston engineer'!). It would mess up the gas mixture in the burner and would probably make little difference to the noise level.

No, Im serious. The fix was to use a solvent weld adaptor on the air intake to reduce it to 21.5mm.

 

[croydoncorgi]

What!? Reduce inlet diameter from 50mm to 21.5 (overflow size)?

Was the problem resonance in the pipe? fan noise?I'm not aware of a 'common' problem on C25s anyway.....

And we still don't know what Keston is involved in this current problem.... If it's a K130 or K170 - yes - noise out of the air inlet is VERY likely an issue.

 

[htgeng]

What!? Reduce inlet diameter from 50mm to 21.5 (overflow size)?

Was the problem resonance in the pipe? fan noise?I'm not aware of a 'common' problem on C25s anyway.....
.

21.5mm is correct. The problem was that the boilers sounded like a misfiring motorbike when they fired up. The CO2 was checked as correct. The keston guy attended a couple of C25s which I reported with noise problems and this was the fix that was used.

 

[croydoncorgi]

Applying general principles of gas combustion, it seems to me impossible that reducing the air supply to a burner that much could do anything but screw it up completely!
However... if it was subsequently possible to check and adjust CO2, I assume you mean that the restriction was placed INSIDE the boiler (there is a 32mm plastic intake duct leading to the fan inlet...). (If the restriction was on the main 50mm external inlet it would have absolutely no effect until the boiler cover was in place!) Restricting 32mm down to 21.5 is still a very big choke on the air.

I'm also trying to understand what was causing the noise. If there was a 'motor' noise coming out of the INTAKE, that suggests the burner was lighting back,so that the gas/air mix in the fan and burner plenum was detonating. Sounds absolutely horrific! Firstly, the burner surface would need to be damaged to allow the flame through (Mr Davy's magic lamp, etc.) and secondly the gas/air mix must have been too lean if it went bang. Restricting the air MIGHT have corrected the ratio (maybe!) but that's not the way the premix burner / gas valve setup on the Celsius is supposed to work, AIUI.

But all this may be completely off-topic and irrelevant.
Emzedcee: PLEASE tell us what model of Keston is involved

 

[htgeng]

. Sounds absolutely horrific! Firstly, the burner surface would need to be damaged to allow the flame through (Mr Davy's magic lamp, etc.) and secondly the gas/air mix must have been too lean if it went bang.

You know your stuff! well the cracked burner sounds more plausible. I have since only worked on Atag boilers and one of those had a cracked burner plate due to being dropped. It was noisy too and was fine once the plate was replaced.

 

[Agile]

On the Gianonni burner/heat exchanger assemblies which virtually all the cheaper boilers use then its quite easy to get it to burn on the inner gauze if the mix is wrong.

It always disappoints me that these manufacturers do these "little fixes" which they will not publish or even admit. The Vaillant "10mm hole" in the air intake tube is an example.

Tony