The StoveBay.com offer a comprehensive range of stoves that are room sealed stoves designed to use an External Air Supply for combustion.
All stoves require air in order to light and stay lit [combustion]. External Air Kits provide an independent air supply that is taken from outside via an air duct. The air duct is connected from an external wall to the back of the stove, and it is this air that allows for combustion and thus heat.
These types of stoves are useful in modern airtight or well sealed homes that cannot take air from the room itself.
Having no External Air Kit in a recently built airtight home may mean that you struggle to keep the stove lit, have a lazy fire flame, poor heat output, smoke into room, and an all around under performing stove.
Older homes are not as airtight as newer homes so they may have sufficient air flow throughout the house to maintain stove combustion, therefore, have less need for an External Air Kit.