I see a lot of discussion here about outside air kits. I had always considered them a good idea.
However, I remember talking about them with my Dad, who was a mechanical engineer who somewhat specialized in factory power/heat efficiency, and he disagreed.
His arguments AGAINST outside air kits were as follows:
1. If it's cold outside, bringing cold air into the firebox will decrease the amount of heat available to:
a. fully burn the fuel efficiently, and
b. put heat into the room/house, and
c. send up the stack to keep the stack temp high enough to keep the draft rolling and avoid creosote condensation on the stack.
If you don't use an outside air kit, and instead allow the warmer room air to provide combustion air:
1. there will not be as big a Δt between firebox air temperature and room air temperature, so there will be more heat available to:
a. burn the fuel efficiently,
b. put heat back into the room, and
c. send enough heat up the stack.
In a nutshell, Dad's assessment of it was, "There's no free lunch, and it's six of one and half-a-dozen of the other."
In other words, the outside air kit would not yield any more useful heat from the fire...either way, you would end up with the same thing and the same basic efficiency.
So, his argument against OAKs was, "What's the point of that expense? It doesn't get you anything."
I should add that this discussion was in relation to an old, not-particularly-tightly-sealed farmhouse.
I would be curious to hear the collective's thoughts on this.
Are OAKs a "pipe dream"?
However, I remember talking about them with my Dad, who was a mechanical engineer who somewhat specialized in factory power/heat efficiency, and he disagreed.
His arguments AGAINST outside air kits were as follows:
1. If it's cold outside, bringing cold air into the firebox will decrease the amount of heat available to:
a. fully burn the fuel efficiently, and
b. put heat into the room/house, and
c. send up the stack to keep the stack temp high enough to keep the draft rolling and avoid creosote condensation on the stack.
If you don't use an outside air kit, and instead allow the warmer room air to provide combustion air:
1. there will not be as big a Δt between firebox air temperature and room air temperature, so there will be more heat available to:
a. burn the fuel efficiently,
b. put heat back into the room, and
c. send enough heat up the stack.
In a nutshell, Dad's assessment of it was, "There's no free lunch, and it's six of one and half-a-dozen of the other."
In other words, the outside air kit would not yield any more useful heat from the fire...either way, you would end up with the same thing and the same basic efficiency.
So, his argument against OAKs was, "What's the point of that expense? It doesn't get you anything."
I should add that this discussion was in relation to an old, not-particularly-tightly-sealed farmhouse.
I would be curious to hear the collective's thoughts on this.
Are OAKs a "pipe dream"?
