How to Install Venting for Tankless Water Heaters

Tankless water heaters are energy and space efficient appliances that deliver hot water on demand, without the longer term storage of water in a large holding tank. A tankless heater must be directly or indirectly vented to the outdoors, because of the thermal output involved in quickly heating water. This can be accomplished in any setting with a run of stainless steel duct work, and a vent and a vent hood.

Things You'll Need

• Stainless steel duct work
• Metal duct tape
• Duct vent hood
• Circular hole saw fitted with diamond blade
• Steel duct work vent mounting brackets
• Drill and screws
• Silicone caulking or spray foam expanding insulation

Instructions

1. Outline the path the duct work will take from the tankless unit in its mounted position on the wall to the vent position on an exterior wall. Ensure that the the mounting brackets can be attached to the surfaces along the path.

2. Mark the termination point of the duct work on the exterior wall, and mark where you will make the cut for the exit vent. Ensure that the location of the hole made on the interior clears the ground level by at least 6 inches on the exterior.

3. Cut the vent exit in the exterior wall from the interior with the hole saw. The exit hole should be cut to accommodate the diameter of the duct work snugly, but not crush the duct work.

4. Mount and connect the steel duct work in sections, working from the exhaust output at the bottom of the tankless unit, along the path to the exterior vent location. Secure mounting brackets with screws.

5. Run a bead of silicone caulking around the outside of the last piece of duct work before it slides into the vent hole. Run a bead of silicone around the perimeter of the vent opening and duct on both the interior and exterior exposures.

6. Tape all the duct seams with metal tape. Use screws to mount the vent hood over the duct terminus on the exterior vent.

Resources

• Tankless Water Heater Systems