Wow... this was quite a thread. Not completely surprising, given that there
is always a lot of banter on the subject..
The math stuff was good.
The science stuff was good.
Make up air... draft air... negative pressure... chimney effect.
Lot's of good stuff.
I'd just like to add this, with regard to wasting/saving.
I think those that have tried many combinations, are in a better
position to offer their results.
Not to be confused with scientific fact.
But let's face it, we are talking about real world
"what you got"...
I have used no damper.. MPD.... baro.
Currently I have all three options, giving a lot of combinations.
I burn the same amount of coal just about every year.
House is about the same. Heating season about the same.
I can honestly say that I have not saved or wasted any substantial
amount with any of them.
In all fairness, my draft fluctuation is not that great.
When talking with a Harman rep, and asking about the
occasional spike to .08-1.0, he said 'what's the problem?'
Coal is so slow to react to occasional flux, that he doubted you would ever
notice a difference.
I did not ask what he thought of MPD's, because obviously he would
not give me an answer, that would differ from their brochures..
But plenty of people use them.
And the "death threat", is really not founded, as annually there
is usually none.. It's generators, and kerosene space heaters
that kill more via CO.
My opinion is that all of the air has to come from outside.
No matter what.
To think that the baro is taking in 70° is tons better than 300 in the pipe,
is not taking into account that you heated the air, to that 70 degrees.
And... when your stovepipe is hotter, it is radiating some of that heat
that you think is all wasted.. I have nearly as much surface area of pipe,
as I do stove. So that heat, is staying in the house.
Wrapping up... (if you don't have crazy draft, like some do, I understand)
I really don't see any waste/gain to get too excited about either way..
Between baro vs. MPD