[Stoves] Energy loss into stove walls

[Crispin Pemberton-Pigott]

Dear Friends

Dean quoted Dale saying,

" The heat lost from the gases goes to 2 places.  A portion of the heat goes
into the stove body and is retained in the body.  Another portion goes into
the stove body but then passes through and into the environment.  For the
lightweight materials, the amounts of heat going into the 2 places are
generally about equal.  "

This can only be true of the cooking time is a certain length.  If the
cooking time is 1 hour, and the amount of heat absorbed is equal to the
amount of heat lost through the walls, then cooking longer will see the heat
passing through is exceeding the heat absorbed.  The amount of heat absorbed
is fixed and the heat lost variable with time.

A heat recycling stove does not follow the path described by Dale at all.

This consultation is a very good demonstration of two important things:
Stoves with long cooking times, like institutional stoves, make fixed
investments in the body and then that loss is fixed and is a small % of the
total heat generated if it is a long 'cook'.  Second, if all the heat
passing through the stove body is recovered for air preheating, the loss
from that is nil. Thus air preheating stoves with long service times can be
made from just about anything that lasts and is cheap, giving the designer
far more scope for expressing creativity.

Regards
Crispin