Saturday, November 05, 2011

Inset Stove Design and Some Tests Part 3



Here is a very basic but effective test to show if you are getting a proper outward and upward flow of convection hot air. It involves nothing more than a strip of lightweight tissue paper placed across the length of the convection grill.

The Basis of the Test

Think about this for a moment - if you were to place a narrow strip of lightweight tissue paper across the top of just about any operating convector heater, what would you expect might happen to the tissue?

(a) Would it be wafted upward by a current of hot air?
(b) Or, would it be sucked down onto the top of the heater?

Think “hot air balloon”  - think why does smoke go up a chimney.

So on an inset stove you will find a grill or grills at the very top of the stove above the glass door. The grill is the convection grill.

IF THE STOVE IS OPERATING CORRECTLY there will be an outflow of hot air from this top grill.

FACT: Most of the heat from an inset stove has to come by way of the convection system. If the convection system is not operating properly, the stove efficiency will be severely reduced. If the convection system is completely dysfunctional, the stove may be some 60% less efficient than it should be.


CAUTION: Before attempting any tests you should be fully satisfied that there is no danger of an accident occurring. If you don't feel confident - then don't do the test.

A piece of lightweight tissue paper about 35 x 7cm is simply gently placed on top of the grill/s for a few seconds. If there is any reasonable convection process taking place, the tissue paper will be wafted upwards - maybe not a lot -  but there should be some lifting of the tissue.

If it is not being wafted upwards in the hot airflow - or indeed if the opposite happens to be the case - and it is being sucked down onto the grill, you have a problem.


1.    No upward current of hot air = no convection taking place. This could be a blockage in the convection channels - or it might be bad design.
2.    The tissue being sucked down onto the grill = a negative air current which mean not only do you NOT have convection, BUT ALSO any heat in the convection chamber is being vacuumed up the chimney. You have a faulty inset stove. This could be a cracked stove or it could be bad design causing this to happen.


The number (2) of the above problems is what is happening with a Blacksmith "Artisan" stove I have encountered. I am wondering if this is a singular problem, or are there perhaps other Artisan owners out there who might be experiencing the same problem?

If you own a Blacksmith Artisan, I would like to hear from you how well you find the convection system operating.

Q1 - Do you get a good blast of hot air from the top grill?
Q2 - Or if you decide to do the tissue test - did you find the tissue being sucked down onto the grill?


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