Heat Shields

How To Reduce Clearance to Combustible Requirements Using Heat Shields

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Nanaimo Chimney Services

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Heat shields are a great way to reduce required clearances to combustibles.  The information in this article is intended as a guide.  For specific details to your clearance reduction requirements, you should contact your, Local Authority Having Jurisdiction (AHJ), local Certified Chimney Professional.

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B365-17 Installation Code for Solid Fuel Burning Appliances and Equipment

Claue 8.2.4. and Table 3 in the B365-17 specifies the clauses for the installation of a compliant clearance reduction heat shield for certified and uncertified appliances.  
https://www.scc.ca/en/standardsdb/standards/28961.
​Purchase B365-17 Code for Solid Fuel Burning Appliances and Equipment - CSA Webstore

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Reducing Clearance to Combustibles Using a Heat Shield

The table below illustrates that a maximum of 67% of clearance reduction can be achieved by using a compliant heat shield.  Alternatively, a pre fabricated heat shield that is certified under ULC-S632 may be used.

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Heat Shield Clearance Reduction By Material

DIY heat shields may be constructed using sheet metal, ceramic tiles, bricks, or a combination of sheet metal with brick or tile.  We offer prefabricated, listed clearance reduction heat shields through our stove shop.

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Heat Shield Construction Rules

• Minimum space between shield and combustibles: 21 mm (7/8 in.).   
• Minimum clearance along the bottom of shield: 25 mm (1 in.).   
• Maximum clearance along the bottom of shield: 75 mm (3 in.).   
• Minimum clearance along the top of shield at ceiling: 75 mm (3 in.).   
• Shield extension beyond each side of appliance: 450 mm (18 in.).   
• Shield extension above appliance: 500 mm (20 in.).   
• Edge clearance for ceiling shields: 75 mm (3 in.).   
• Adhesives used in shield construction must not ignite or lose adhesive qualities at temperatures likely to be encountered.   
• Mounting hardware must allow full vertical ventilation.   
• Mounting hardware must not be located closer than 200 mm (8 in.) from the vertical centre line of the appliance.   
• Mounting hardware which extends from the shield surface into combustibles may be used only at the lateral extremities of the shield
• Shields must be permanently mounted to walls and not temporary or a folding type shield.
  

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Clearance Requirements for Uncertified Wood Stoves

An uncertified wood burning stove has not been tested, and certified by an accredited lab under ULC-S627.  As such, the following clearance to combustibles are required in Canada.  Please check your local Authority Having Jurisdiction (AHJ) to determine if an uncertified stove is permitted to be installed in your area.

Clearance to combustible requirements for non certified radiant wood stove is 1200 mm (48").  A stove with a metal jacket casing requires 900 mm (36").  Wood stoves certified for installation in an alcove may not be reduced, unless otherwise stated by the appliance manufacturer or AHJ.

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Clearance Requirements for Certified Stoves in Canada

Wood burning stoves that have been safety tested for use in Canada are tested under ULC-S627 - Standard for Space Heaters for Use with Solid Fuels.  When the wood burning stove is tested and certified by a Standards Council of Canada accredited test lab, the clearance requirements for the installation of the wood burning stove will be outlined in the manufacturers installation manual.  The manufacturers installation instructions must be adhered to to comply with the installation requirements.

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Wood Stove Change Out Rebate

Uncertified wood burning stoves are generally inefficient, and contribute to poor air quality.  There are wood stove change out programs that offer rebates when an uncertified stove is changed out for a new efficient wood burning stove with low emmisions.  The CVRD is a municipality on Vancouver Island, British Columbia, Canada that offers rebates.

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