The selection of a tankless water heater is one of the most important decisions a homeowner makes to decrease utility expenses and lower energy consumption.

Once selected, the venting of a gas tankless water heater will be the most important decision a tankless water heater installer makes when fitting a home or building with a unit.

Tankless hot water heaters require special venting to blow hot exhaust gas outside, where it dissipates. Unlike traditional tank-style water heaters, gas tankless hot water heaters offer far more versatile venting options.

In fact, advances in unit design have made the installation of energy-efficient tankless water heaters less expensive, more attractive, and easier to fit within your home plan, all while saving space.

Tankless Water Heater Venting Features

A professional tankless water heater installer will inspect your home for the best fit. Here are seven key points to keep in mind when deciding where to mount your new tankless water heater and how to configure the venting.

1.  Indoor tankless water heaters draw in outside air. Tankless water heaters are vented in two ways: direct vent and power vent. Direct-vent units pull in air from outside the home or building and have two vents, one for intake and one for exhaust. This configuration allows tankless units to fit in smaller spaces; in fact, tankless water heaters save up to 16 square feet of space. Power-vent units only require an exhaust vent and must be placed in a larger area for adequate air quantity for combustion.
2. Outside tankless water heaters free up indoor space. Tankless units withstand below-freezing temperatures thanks to automatic, self-warming components and can therefore be installed outside in warmer climates. Installing a tankless water heater outside frees up indoor space and requires no additional venting.
3. Tankless water heater design allows for multiple venting options. Tankless water heaters can vent through the roof or a side wall, creating more flexibility and options for placement. Traditional gas tank water heater require venting through the roof. Tankless water heaters use fans to blow exhaust from the unit horizontally, allowing vents to terminate on the side of a house.
4. Condensing tankless water heaters lower the cost of installation. Tankless water heaters with condensing technology are up to 95% more efficient than non-condensing units and emit a comparatively cooler exhaust gas, according to the Propane Education and Research Council. The exhaust vent can therefore be PVC or polypropylene and not metal, a feature that lowers the cost of installation.
5. Tankless water heaters with a concentric vent design offer additional safety benefits. A 5” concentric vent contains both intake and outtake pipes, so the vent is cool to the touch as warm air is insulated inside. If a pipe develops a leak, the air stays in the concentric vent and does not enter the home.
6. Recess boxes allow tankless units to fit inside walls and not stuck on home exterior. Certain home builders now offer recess boxes for non-condensing tankless water heaters. This configuration allows the unit to fit inside of the house’s framing and not hang off the side.
7. Pipe covers and creative termination points offer aesthetically pleasing venting solutions. Take advantage of tankless unit manufacturer options and installers’ technical skills to conveniently obscure pipes.

To plan your installation, find a tankless water heater dealer in your nearby area.

More tankless unit installation information is also available in the Tankless Buyer’s Guide.