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Publications GAS TRADE: UNIT 22 (5th ed. pub. 2015)

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GAS TRADE: UNIT 22 (5th ed. pub. 2015) - Venting practices

Publication Year:

  • 2015

Total Pages:



  • CSA
CSA Group's 2015 Gas Trade materials reference the Red Seal Program's trade outlines for your preparation to become a nationally recognized gasfitter. Please visit the Red Seal Program's website for more details.

Unit 22 - Venting practices


The main functions of venting systems are:

  • To completely vent the flue gases to the outdoors without spillage into the building. (This ensures that the indoor air quality of the building is not compromised by installed appliances)

  • To effectively vent at a rate that ensures the proper operation of the appliance

  • To operate safely in terms of fire

  • To keep the weather out of the building.
All forced-air gas-fired furnaces manufactured or sold in Canada after January 1, 2010, are required to be high-efficiency, condensing-type appliances that are vented into special venting systems (BH vents). However, there are still a large number of existing low- and mid-efficiency furnaces along with currently manufactured and existing water heaters, boilers, and space heaters that operate with natural draft venting systems.

It is more important that gas technicians/fitters understand the requirements for proper installation and operation of natural draft venting systems since technicians/fitters must make crucial decisions regarding the size, location, and type of material for natural draft vents.

Learning Objectives:

At the end of this unit you will be able to:

  • Describe venting systems.

  • Describe vent design and installation requirements.

  • Size venting systems.

  • Describe vent installation and assembly.

  • Describe vent inspection.

  • Locate and size air supplies for equipment with inputs of 400 MBtu/h or less and over 400 MBtu/h.

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