andrew heggie wrote:
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. 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.


The aga ticks over at around 1KW continuous. Thats about right we find
for march to June, and September to November. That heats about 200
square meters of house floorage.

June,July and august, its out.

December January and February we chew three times as much oil heating
the house conventionally with an oil boiler, as the aga uses all year.

Then the aga is capable of heating just the kitchen, about 30 sq meters.

The key to all this is plenty of thermal mass in the house. It makes
more sense with a high occupancy ratio.

which we have also. The house is seldom empty for more than 2 hours.

To be honest, if we had 24x7 wood burners all over he place, ticking
over at 1kw per room,. that would be fine as well..if you bother to
manage them.

I guess thermostatically controlled dampers might be useful as well.

Bur the great thing about burning fuel where you are - and free fuel at
that - is that its very efficient and low collateral energy fuel.

15 minutes with a chainsaw (about 100cc of petrol) and 20 minutes with a
hatchet has me a weeks supply of firewood. I'd estimate something like
300kwh worth. In terms of open fires. More if nrnt in a stove.


Probably around £15-£20 of oil equivalent. At least. More in a stove. A
lot more.

BUT it needs managing..







AJH