On 2007-12-24 15:16:41 +0000, andrew heggie said:

On Mon, 24 Dec 2007 07:09:30 -0800, tom.harrigan wrote:

aga suggest you need 47.5kg of
solid fuel to get 220kWh. Unless I've done something wrong, that makes
it about 70% efficient.

I haven't checked your maths, nor do I know the calorific value of your
fuel but coke burning devices always look good because the LHV
and HHV are the same. My beef with the aga is that it gives you the heat
when it wants to.

Actually not true.

The heated metal mass in the core of the cooker is very well insulated
from the exterior. The heat is therefore not released in substantial
quantities at all.




Now this is fine with solid fuels because they all have
this thermal inertia problem but it's an unnecessary restriction when
burning inherently "better" fuels like gas or oil.


Not at all. With a gas supply, the burner used is a modulating type,
the output of which is a few hundred watts when the core is fully up to
temperature. The burner output increases when heat is extracted for
cooking and other purposes.