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ASHRAE Proposes Removal of Residential Backdrafting Tool

Combustion appliance backdrafting test requirements would be removed from the American Society of Heating, Refrigerating and Air-Conditioning Engineers’ (ASHRAE) residential ventilation standard under a proposed addendum.

ASHRAE Standard 62.2, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings, is the only nationally recognized indoor air quality standard developed solely for residences.

Proposed addendum 62.2a was approved for a first public review at ASHRAE’s 2004 Winter Meeting. It opened for public comment on March 12 and closed on April 16.

The proposed addendum is the first for the standard, which was published in December 2003.

Backdrafting prevents exhaust from appliances such as furnaces from entering the house. The proposed addendum addresses concerns about the backdrafting test.

“The test was based on the best industry-accepted method found in the National Fuel Gas Code but questions have arisen about its application to solid-fuel burning appliances,” committee chair David Grimsrud said. “There also is concern about it not being possible to perform the test until the home is completed, opening the potential for having to perform remedial balancing at a difficult stage of construction and sale.”

Although the proposed addendum eliminates the test requirements, it sets an upper limit of exhaust flow to 15 cfm/100 square feet when natural-draft combustion appliances are present. It requires designers or installers to address the level of depressurization at a stage where the problem can be fixed, he said.

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