Stack Flow and Loss Measurements of a Commercial Tank Water Heater

The purpose of this study is to better understand the stack losses of a commercial tank water heater. The measurements will be used to help interpret an ongoing study of the heater energy use and domestic hot water (dhw) demand and estimates of standby losses.

The heater has an input of 365,000 Btu/h, a 70-gallon storage tank, and a recovery efficiency of 70%. It is equipped with intermittent ignition, an integral flue damper, and can be fitted with a thermal vent damper. The thermal damper is located after the draft diverter. The integral flue damper is installed vertically in the rectangular hood and is motor actuated. The damper does not seal air tight. When the damper is closed, the open duct area is reduced from 103.0 to 6.74 square inches for a 93.5% reduction in the open area.

Full report (PDF)
Stack Flow and Loss Measurements of a Commercial Tank Water Heater