Scary fumes from Keston celsius 25.

[Boiler man]

Hi,guys.Today I was very scared to see black smoke from my flue it was terrible I switched my boiler off right away. The black fumes were stinking I had to use storage heating all day. It was puffing like a very hot coal fire the noise inside was terrible.I knew it was no sort of steam : it was stinking it was black And i held a cold glass on top of the flue it did not steam up. Please help! Do any of you know what might be causing this? ps.The radiators were not hot.Lucky i got back up immersion heater for hw. THANKS. Your help is greatly appreciated.

[Doctor Drivel]

Sounds too serious for DIY. call in Keston ASAP.

[Bob Martin]

See if there is any water in the boiler circuit.

[Bob Mannix]

When was it last serviced? If it was a few years, the heat exchanger has probably got sooted up. It's an avalanche process (the more it soots up the faster it soots up) until you get the terminal situation you describe. "Someone" will have to clear all the soot from the heat exchanger fins. I would recommend not using the indoor vacuum cleaner to do this, as soot is incredibly fine carbon powder. Mine did the same (depositing soot up my bl**dy newly painted render, damn it). Fine after it had been cleaned though. Mine has a spyhole to see if the pilot is alight, you can see the flames as well. If they show a tendency to be yellow rather than blue, the process has probably started or it's just maladjusted. Either way it needs a service/clean.

[Boiler man]

the boiler was fitted 2 weeks ago

[Boiler man]

I will now I regret choosing keston i would be better off with a vaillant ecomaxpro.

[Boiler man]

i checked it is dry as a bone.

[Ian Stirling]

By you? If not, pick up the phone and start complaining.

[andrew]

Any description of what they smelt of? e.g. burning plastic?

I can only imagine either soot from poor combustion (lack of air flow through heat exchanger), or some part inside caught light which isn't supposed to, such as the flue pipe perhaps? Was the mixture tested during commissioning? I think it uses the air pressure drop due to air flow to modulate the gas valve, so unless the gas valve got stuck open or the mixture was very badly out, it's difficult to think how you would get a gross excess of gas at the burner. Have you looked inside the casing to see if it's all one large melted blob at the bottom?

Anyway, sounds like a callout to your installer or Keston is required.

[Ed Sirett]

I hope my own does not develop this fault. There is a flue over-heat cut out which I suppose should have stopped the boiler but I guess the exchanger was still managing to cool the soot stream.

My suspicion would be the gas valve. These seems to be the weak link on this unit. About 50% of the ones I've installed have had some sort of trouble - My own has developed a thunderous roll on ignition that lasts up to 10 seconds. When tested with the combustion analyser it's fine but my guess is the GV is not doing the business for the first few seconds.

This boiler is going to take some work. Assuming its the gas valve then you will need a new one, maybe a new burner and a thorough "decoke" of the exchanger and the flue.

[Andrew Gabriel]

If it really was burning that sooty, it probably wasn't generating anywhere near as much heat as it's designed to anyway. However, I could also imagine the combustion wasn't all on the burner guaze, and sooty flames could have been going through the heat exchanger, and possibly as far as the plastic consetina flue pipe.

Oh dear. The only issue I've had with my gas valve so far was the supposedly factory adjusted mixture was miles out.

Other than the top of the top row of pipes which you can get to if you take the burner off, the rest of the heat exchanger is pretty much completely inaccessible as far as I can see.

[Ed Sirett]

It seems that the OP has a unit that is under warranty - it's going to cost Keston some to put this right.

Do you know of anything that dissolves soot. I mean detergent and a scrubbing brush will have some effect but is there a solvent for graphite? can it be bough? what else might it dissolve?!

[Boiler man]

no it was installed proffesionally by a corgi installer. i am no plumber

[Boiler man]

no it was installed proffesionally by a corgi installer. i am no plumber

[Boiler man]

no it was installed proffesionally by a corgi installer. i am no plumber

[Ian Stirling]

Well, to paraphrase the Blondie song. "Call Him".

[Dave Plowman (News)]

Why the moniker, then?

[Rob Morley]

Soot isn't graphite (nor is it diamond). I'd be inclined to try oxy-acetylene, but stop quickly if it gets hot enough for the steel to burn. :-)

[Ed Sirett]

AIUI there are three allotropic forms of Carbon: Diamond, Graphite and Fullerine. AFAIK Anthracite, Coke, Soot, Graphite are various form of graphite although the large scale (relative to the atomic scale) structures and trace contaminants vary.

The oxy-acetylene would make a mess of the plastic flue components.

[Rob Morley]

I thought amorphous forms of carbon didn't count as graphite - obviously I was wrong. :-)

It would indeed :-0