Tankless Water Venting

[Mike Oliver]

I want to install a 199K btu NG tankless water heater in my basement and have a question about venting. Due to several obstacles, (floor joists and wall) I need to use 3 90 degree elbows within the last 3 feet of the vent run, as it exits the exterior wall (total run is less then 12 feet). Will this be a problem ?

Also the vent will terminate approx 10 inches away from an Air Conditioner Condenser. How hot is the exhaust from the tankless and will this be a issue ?

Thanks
Ollie
Maryland

[Michael Thomas]

Check the manufacturer's installation instructions, different brands and models of tankless water heaters can have quite different venting requirements.

Based on my experience, I've put together some general information for those considering tankless installations here:

Troubleshooting Tankless Water Heater Installation And Operation - Paragon Property Services Inc. / Home Inspections Chicago (http://paragoninspects.com/home-inspection-tankless-water-heater-installation-problems-faq.html)

[Rick Hurst]

The termination of 10 inches from the condensing unit is reason enough to re-consider.

Its no different than say a laundry vent dumping heated air on the condensor.

This can reduce the efficiency of the equipment and possibly cause overheating.

4ft. clearance is what I've always known.

rick

[Bruce Barker]

If you are using a Type B vent, you may have problems with the 8 feet clearance to sidewall restriction and the 10 feet clearance to an air intake opening such as a window.

That many elbows in a vent reduces the Btu/h allowed for vents in the IRC Chapter 24 vent tables. Check manufacturer's instructions about this.

Type B vents can get pretty hot. If you are going to run it where someone could touch it, you may wish to install a barrier to prevent contact.

Bruce Barker
Dream Home Consultants