New recommendations to contractors installing tankless water heaters


Tankless DHW heaters keep this restaurant in hot water.

An international standards organization has published new recommendations for the installation of instantaneous water heaters to minimize the risk of scalding.

ASSE International has published its sixth scald awareness white paper titled “Recommended Installation Practices for Residential Tankless Water Heaters to Reduce the Danger of Scalding.”

Developed by the ASSE International Scald Awareness Task Group, the white paper lists installer responsibilities, starting with the requirement that a licensed professional install tankless water heaters, that the manufacturer’s instructions are followed, and that all work is performed per local codes

“The ASSE International Scald Awareness Task Group was formed to educate and give guidance to the general public and plumbing industry on the many ways that someone can be exposed to the potential scalding and thermal shock hazards associated with hot water at the point of use,” said Richard J. Prospal, chairperson of the ASSE International Scald Awareness Task Group.

“This white paper focuses on recommendations for the installer to follow when installing a residential tankless water heater or replacing a residential tank water heater with a tankless water heater, and how the dangers of scalding from excessive water temperature can be reduced.”

Prior to installation, ASSE suggests that the plumbing system and the fuel piping are sized correctly, circuit and wiring are safely delivering power, and that if the water heater is a condensing type – the installer makes provisions for proper disposal of the condensate.

After installation, they suggest the installer check for proper water temperature at all downstream fixtures, adjust temperature limit stops at all compensating type shower or tub/shower valves, and review maintenance and operating instructions with the homeowner.

It also addresses some of the potential problems arising from unprofessional installations and the solutions to those problems.

With the advent of tankless water heater technology that can control the outlet temperatures of the water heater to the same specifications as various ASSE International product performance standards for mixing valves, three new ANSI product performance standards were approved – ASSE 1082- 2018, performance requirements for water heaters with integral temperature control devices for hot water distribution systems, ASSE 1084-2018, performance requirements for water heaters with temperature limiting capacity, and ASSE 1085-2018, performance requirements for water heaters for emergency equipment – two of which are featured in the paper.

To download the document, visit


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