On Nov 12, 3:59*pm, wrote:
On Sun, 11 Nov 2012 17:13:54 +0000, geoff wrote:
I still cannot figure why a sophisticated bit of kit like a modern gas
boiler, which is fueled by a gas that is readily combustible, has a
fan, yet a wood fire which has a low cv fuel which is difficult to
cleanly burn and would benefit from the turbulence and air control is
resisted.

It is because most boilers are room sealed, they are not drawing air in
from the room, it has to be sucked in from the outside via the outer
tube in the flue and the products of combustion pushed out down the
inner tube of the flue

That explains why a gas boiler has a fan.

I therefore imagine that because a woodburner has to have a chimney
and that creates its own draught fans aren't used other than in pellet
stoves.

My experiments with small burners is they do benefit from fans

AJH

They need a fan because the flue gases have no buoyancy, they are so
cool, especially in condensing boilers.