The Pelletstove Corner

In a negative pressure system you have a fan downstream of the fire sucking (think vacuum cleaner) and in a positive pressure system you have a fan upstream of the fire blowing (think hair dryer). Most stoves are negative pressure systems. In a negative pressure system if there is a leak infront of the fan the stove draws from the room into the stove and out the vent. Preferable to a positive pressure system which would leak from the stove into the house. Negative pressure systems typically have an air-wash feature which allows a stream of air to leak in and create a curtain of air between the glass (neoceram) and the fire. This keeps the glass cleaner longer. In a negative pressure system the fan blades are in contact with the combustion byproducts and need to be cleaned regularly, also another fan is required to circulate room air through the convection system. In a positive pressure system you often have only one fan pushing air through both the combustion and the convection systems and because this fan is upstream it is not subjected to the heat and particulate matter of the negative pressure system fan.

I would much rather have a negative pressure pelletstove simply because I believe the benefit of having a stove that, if it leaks around the door, leaks into the stove and not into the house outweighs the cost of the required extra room air fan.

I want to clarify one thing here- I negative pressure system can leak into the house, but it can only do so at or downstream of the exhaust fan. A positive pressure system can leak into the house any and everywhere.