If my stove is using 36,000 cubic feet of air every 24 hours that would mean that it is emptying the house 1.1 times per day. Lets round that to 1 and say that once per day the air in my house is being replaced with cold outside air. ( I realize this is not 100% true because the air mixes but for this calculation lets ignore that)
Lets say its 70 degrees inside my house and its 20 outside. If I turned the air over in the house without running the stove the temperature in the house would drop to 20 degrees. Virtually the same as the outside temperature. On average that drop is about 2 degrees per hour. I have no idea how much impact that will have on our stoves but clearly it will have some impact. No?
You're on the right track. Let me do the math for you.
Facts:
temperature _________50
______________________ 70
inside, 20
outside;
= 50
Volume________________36000 cu ft/day_______________25 cfm on 24 hours/day (it is likely that the combustion blower is only running part of the time. See below)
Density of air at STP______0.07967 pounds per cubic foot___The number of pounds of air in one cubic foot at standard temperature and pressure
Specific heat of air at STP__0.24 BTU/lb/degree F__________The amount of heat needed to raise one pound of air by one degree F at standard temperature and pressure
Math:
Volume x Density x Specific heat x
temperature = 36,000 x 0.07967 x 0.24 x 50 = 34,417 BTU/day
34,417 (BTU/day) / 8300 (BTU/lb) / 76% efficiency = 5.456 lbs/day of pellets
Conclusion:
That comes to 0.136 bags of pellets a day to reheat the air that is wasted without an OAK
Even with cheap pellets that's about $0.60/day or $18/month
It gets worse with colder outside temperatures.
If for instance it was 5
outside, the cost becomes $0.773/day
If your stove's combustion blower is not on 24 hours a day, the cost will be proportionately less. If it is on 20% of the time the cost would be $3.60/month in pellets.
For those who don't want an OAK, it's your choice. Do as you please.
Edit:
Did some formatting because the spaces were removed by the forum software
Edit
Corrected math, off by a factor of 10