Tankless water heaters are an energy-saving alternative for homeowners. Since the unit heats up the water as it is needed — rather than heating and storing it in a specific temperature — it requires less energy. You have to be familiar with specific setback for windows when you install a gasoline or propane tankless water heater, and these vary according to the place and if the unit is placed inside or outdoors.
A tankless water heater requires a 4-foot clearance in the side or under a door or window that opens, unless the unit is directly vented to the outside. If the water heater is installed above the door or window, it still needs 12 inches of clearance. A direct port installation only needs a 12-inch setback in the door or window. If the window does not open, the water heater requires a 12-inch blow off.
Outdoor installations are only suitable in light climates where the temperature does not drop to freezing in the winter. When installed on the outside of the home, the tankless water heater must have 12 inches of clearance in any operable door or window. The disadvantage from an inoperable window varies according to local building codes. Additionally, the unit needs an outdoor vent cap.
In addition to door and window setbacks, tankless water heaters should not be installed near dryer ports or intake air vents. If the heater is installed between buildings, then there has to be a minimum clearance of 2 feet and the unit cannot be straight across from a window or door in the facing wall. When installed above a paved driveway or sidewalk, then the port or unit has to be 7 feet above the ground.
When these setbacks are the minimal requirements, your community building codes might have extra setback requirements. A tankless water heater also needs a building permit before it is installed. Additionally, in California, all water heaters must be braced, anchored or secured to the wall studs to make sure they cannot move during an earthquake.