Before you start the hunt for heating appliances, familiarize yourself with the terms “Direct vent”, “B-vent or natural vent” and “Ventless”. These terms refer to the way an appliance gets combustion air and releases exhaust fumes.
A direct-vent unit is one that gets its combustion air from outside the home, then returns the exhaustion fumes outside. It is an enclosed system, requiring no air from the room in which is sits. If your home is considered a “Good Sense” model or has been recently remodeled to be more energy efficient, you may want to take a good look at a direct-vent model. If you are considering a unit for a bedroom, direct vents are the only ones allowed by local building codes.
B-vent systems have no outside air intake system. Instead, they draw combustion air from inside the room where the appliance sits. Fumes are then exhausted to the outside by the venting system. This is the same way an open fireplace operates when you burn a wood fire.
Ventless fireplaces are becoming more common, but are most useful where there is no easy way to vent to the outside. Manufactures of these appliances have information about the safety of releasing exhaust fumes from the gas combustion process into the living space where they can be breathed by inhabitants. These units are not highly recommended where the elderly or small children are present for prolonged periods of time during operation of the fireplace. We have both installed and replaced these units, depending on how homeowners feel about the above issue of exhaust fumes in their homes.
Most product lines with gas heating appliances offer direct vent and B-vent options. Direct venting units usually cost more. While the stoves look the same on the outside, there is much more design and manufacturing that goes into the product that must in-take outside air for combustion. Some stoves have specialty venting systems that are developed just for that stove. Expect venting costs to be a healthy chunk of the installation cost.