In article , Gib Bogle
scribeth thus
On 4/17/2011 8:40 AM, geoff wrote:

The gas pressure needs to be checked first, if it is low the gas and
fuel may not be mixing correctly.

Aah - the gas / fuel mixture

No chance of any carbon monoxide there

Just from first principles (no specific knowledge):

soot implies incomplete combustion

incomplete combustion can give CO

e.g. 4CH4 + 6O2 - C + 2CO + CO2 + 8H2O

Bit worrying that, never seen soot from our boiler and If I did I'd soon
shut the thing down..

Mind you it can do that sometimes 'tho is been well behaved since it had
a new board from Geoff no surprise there needing one after all it's a
Suprima;!...

--
Tony Sayer