Direct vent water heaters are used when the air quality or the air pressure inside a dwelling or commercial facility are not sufficient for a traditional water heater to achieve proper combustion. The heater pulls air in directly from the outside, and then vents the gases from combustion back outside.
Some of the features that a consumer should look for when purchasing a direct vent water heater include a flammable vapor detection system. Because air quality is sometimes a concern in spaces featuring this type of water heater, a control system that turns the heater off if flammable vapors develop is crucial. A heat exchanger featuring a porcelain or enamel coating allows for increase durability, and dual anode rods inside the tank shield it from corrosion.
Some direct vent water heaters can make too much noise when the blower turns on, either to expel combustion gases or draw in more air, so choosing a heater with a quiet blower can be important. Choosing a heater that is designed to produce low toxic emissions is better for the environment and the health of the occupants of the space. For those living at high altitude, it is important to make sure that the heater is certified for applications at the appropriate height above sea level.