On Nov 11, 5:14*pm, geoff wrote:
In message ,
writes

On Sun, 11 Nov 2012 08:31:38 -0800 (PST), harry
wrote:

The fan in most gas gas boilers is working on a mixture of gas and
air.

I don't follow that, I though it was just an induced draught fan after
the heat exchanger?

As usual Harry's confusing things

In most conventional boilers, the fan works on the air or the exhaust
gasses, in modern condensing boilers, quite often, the fan is blowing
premixed air/gas into the combustion chamber

--
geoff

I think that's what I said. Whether it's condensing or not is neither
here nor there.