PART 6 — HEATING, VENTILATING AND AIR-CONDITIONINGUpdated for the 2024 Ontario Building Code
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6.3.2.11.Return-Air System
(1) Return-air systems shall comply with Article 3.6.5.8.
(2) Where a ceiling space is used as a return-air plenum, the requirements of Article 3.6.4.3. shall apply.
(3) A public corridor or exit shall not be used as a return-air plenum.
(4) The return-air system shall be designed to handle the entire air supply.
(5) The return-air system shall be designed so that the negative pressure from the circulating fan cannot affect the
furnace combustion air supply nor draw combustion products from joints or openings in the furnace or flue pipe.
(6) Return-air inlets shall not be installed in an enclosed room or crawl space that provides combustion air to a fuel-fired
appliance.
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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.