[Reposting this from someone here who I think gave the best explanation for using an OAK
In an average home with normal air sealing, the effect on the stove's performance itself, in terms of how well it burns, will likely not be noticeable. But that's not the reason for an OAK unless you have a very tightly sealed home. For any situation where an OAK is added, the primary benefit is a reduction in the amount and rate of air exchanged from the inside to the outside of the home.
Your combustion blower is actively pumping air from inside to outside at a continuous, relatively high rate whenever it's on. Without an OAK, the air used for combustion is air you already paid to heat, drawn from inside the home. Because your house cannot sustain a vacuum (you and the other people in the house needing to breathe, for example) that air will be replaced by colder, often drier air pulled in from the outside through all the tiny little cracks in your home. You will then need to heat that air, and the needlessly expensive cycle continues. You would not, for example, drill a two-inch wide hole in one wall of your living room in January, then drill a three-inch wide hole in the opposite wall, and put a powerful fan in that hole, and turn it on all day, every day. Yet that is what is happenening when you don't use an OAK. Your stove is powerful enough to overcome that situation, but it works much harder to do so by burning more pellets than you would otherwise need to burn. You also feel more cold drafts near the floor, caused by the outside air being pulled toward the stove.
With an OAK, that combustion air is simply pulled in through the OAK, used for combustion, and exhausted back outside. None of your heated, nicely humidifed air is needed. You spend less money, and remain more comfortable. That's a pretty good deal for just installing a small metal tube.[/quote]
In an average home with normal air sealing, the effect on the stove's performance itself, in terms of how well it burns, will likely not be noticeable. But that's not the reason for an OAK unless you have a very tightly sealed home. For any situation where an OAK is added, the primary benefit is a reduction in the amount and rate of air exchanged from the inside to the outside of the home.
Your combustion blower is actively pumping air from inside to outside at a continuous, relatively high rate whenever it's on. Without an OAK, the air used for combustion is air you already paid to heat, drawn from inside the home. Because your house cannot sustain a vacuum (you and the other people in the house needing to breathe, for example) that air will be replaced by colder, often drier air pulled in from the outside through all the tiny little cracks in your home. You will then need to heat that air, and the needlessly expensive cycle continues. You would not, for example, drill a two-inch wide hole in one wall of your living room in January, then drill a three-inch wide hole in the opposite wall, and put a powerful fan in that hole, and turn it on all day, every day. Yet that is what is happenening when you don't use an OAK. Your stove is powerful enough to overcome that situation, but it works much harder to do so by burning more pellets than you would otherwise need to burn. You also feel more cold drafts near the floor, caused by the outside air being pulled toward the stove.
With an OAK, that combustion air is simply pulled in through the OAK, used for combustion, and exhausted back outside. None of your heated, nicely humidifed air is needed. You spend less money, and remain more comfortable. That's a pretty good deal for just installing a small metal tube.[/quote]
