Lab Testing of Tankless Water Heater Systems

The objective of this study was to inform the Northwest Energy Efficiency Alliance (NEEA) and its members regarding the current level of performance of tankless water heaters, their potential energy and cost savings, as well as reliability and safety.

A thorough laboratory evaluation was conducted of a sample of these products, most of which were donated by major tankless manufacturers. These products included popular models that are condensing, non-condensing, as well as low, medium, and high capacity. Testing included performance verification of the Uniform Energy Factor (UEF) in a minimally compliant installation according to the National Fuel Gas Code, as well as a stress test under adverse operating conditions simulating an improper installation that starved the water heater of gas pressure during operation. Additionally, a code review was conducted to determine under what circumstances existing ½” gas lines could be reused for tankless retrofits.

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