How an Inset Stove
Should Work - part 1
Some concern about the functioning of a friends Blacksmith Artisan inset stove has sparked this series of posts concerning the design, efficiency, and function of inset stoves generally.
Above is a diagram of a typical inset stove. An inset stove is essentially two boxes - one inside the other.
(1) THE INNER OR FIRE BOX
The inner box is the "Fire Box" in which the fire burns. It usually has two air supplies, a primary air supply which allows air to come in underneath the fire, and a secondary air supply which allows air in above the fire. In some designs the secondary air is arranged so as it acts as an air wash to keep the door glass cleaner by wafting the combustion fumes away from the glass.
(2) THE OUTER BOX
The outer casing forms the "Convection Heating System". It is absolutely vital that the air in the "Convection System" DOES NOT MIX IN ANY WAY with the air used for combustion. If it does mix, at the least it will cause the stove to be very inefficient, and at the worst, it may allow noxious fumes into the room.
Possible causes which might allow the two air flows to mix are:
(1) a crack in the casing, or
(2) poorly sealed joints, or
(3) bad design.
COMBUSTION AIR AND CONVECTION AIR
SHOULD NOT MIX
The Vital and Distinguishing Part of an Inset Stove
The distinguishing and vital part of an inset stove - and clearly different from a free-standing stove, is the outer "Box" or "convection airway" which causes air to circulate in and around the back, sides, and top of the inner box or "Fire Box" - thus carrying the heat from these surfaces out into the room..
Without a properly functioning convection system, an inset stove would be no better than a simple door on a fireplace, as the heat from the back, sides and top of the stove would simply be lost up the chimney..
TWO SEPERATE AIR SYSTEMS
How should the air flow systems work in an "Inset Stove"?
First point to remember is that there are - 2 - TWO DISTINCT AIR FLOW SYSTEMS to consider. The FIRST rule is that these two air flows should not mix.
I will write further on this very soon. Look out for the next post on this subject.