Appliance Air Intake Clearance From Regulator / Over Pressure Relief Device Vent Outlet

30 December 2016

Reference #:  D-GA 2014-04 Rev 01

This directive is being issued by a provincial safety manager pursuant to section 30 of the Safety Standards Act.

General Details

There are instances within the CSA B149.1 Natural gas and Propane Installation Code where further clarity is required regarding minimum clearances. This directive defines the minimum clearance requirement for appliance air supply inlets (combustion air) in order to resolve installation related conflicts in British Columbia.

Specific Details

An appliance air intake is not defined in the CSA B149.1, therefore in British Columbia it shall be categorized in two ways, either as passive (natural draft combustion air intake) or fan/blower assisted (mechanically draws air in for combustion).

BC Safety Authority interprets the appliance air intake referenced in Table 5.2 to be as passive based on past use of the term in relation to Category I or II appliances. Piping systems supplying combustion air to a Category III or IV appliances installed as direct vent 2 pipe installations shall be considered as fan/blower assisted. Fan/blower assisted appliance air inlets for both Natural Gas and Propane installations are to be terminated no less than 10ft (3m) in any direction in accordance with the clearances for mechanical air intakes in Table 5.2 from a regulator relief or over pressure line relief device outlet where gas may be vented to atmosphere.

Clearances from the discharge of a certified overpressure protection device that conforms to ANSI Z21.80/CSA 6.22are listed in the first column in Table 5.2. Passive air intakes must have a clearance of 1ft (.3m). Fan/blower assisted air intakes must have a clearance of 3 ft. (1 m).

Brad Wyatt
Provincial Safety Manager - Gas 

Safety Standards Act
Gas Safety Regulation
CSA B149.1 - Natural gas and propane installation code