Heat shields and Mantle Shield Reductions

elkimmeg Posted By elkimmeg, Dec 29, 2005 at 4:32 AM

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  1. elkimmeg

    Guest 2.

    This question has been asked many times How can safely I reduce clearances? The common way outlined by NFPA 211, is noncombustible wall protection with 1” air space. Depending upon construction and various materials, clearances can be reduced up to 66% but no less than 12” However manufactures supply heat shields that are tested and certified, that may further reduce clearance closer than 12”. Unfortunately this heat shield may be only attached to the rear or bottom. What about the sides? What about stoves that manufactures do not offer heat shield options?
    What if one were to manufacture there own heat shields? And attach them to their stoves with noncombustible spacers? In theory the shields provide air space and natural convection that dissipates heat. Which is what it supposed to do. That heat removed and the stove surface cooled, affords closer distances to combustibles.
    Since there are no generic manufactures, I am aware of, or any generic codes governing reductions. There is no safe way to determine what reduced distance is a safe distance?. USA is not the only country with safety standards. Our neighbors to the north, Canada, have even more restrictive codes. It is here where actual codes govern heat shield reductions. “CSA B365 Installation Code for Solid-Fuel-Burning Appliances and Equipment");

    “You can find guidelines for installing these uncertified stoves in the solid-fuel-burning installation code, CSA B365. The lowest clearances to combustible materials for uncertified stoves are large – 1200 mm (48 in.) for radiant stoves and 900 mm (36 in.) for stoves surrounded by jackets behind which convection air can flow.

    Clearances to Combustible Material for Appliances Using Solid Fuel
    Source: CSA International B365-01, Table 2
    Minimum clearance, mm (in.)
    Application Top Sides, rear
    and corner Fuelling and ash
    removal side(s)
    Appliances with no shielding* 1500 (60) 1200 (48) 1200 (48)
    Appliances with shielding* 1500 (60) 900 (36) 1200 (48)

    * Shielding consists of protection such as external jacketing or a metal heat shield attached to the sides and rear of the appliance and spaced out at least 50 mm (2 in.) by non-combustible spacers, with provision for air circulation at bottom and top.

    Note: Clearances shall be measured from the outer surface of the appliance to the combustible material; a non-combustible covering applied over the combustible material shall be disregarded.
    Reduce Minimum Clearances Safely

    Like most homeowners, you probably want your wood stove to take up as little floor space as possible. As a result, heat shields are often used to reduce clearances and protect walls and ceilings. Some stove manufacturers offer certified accessory shields with their products to provide reduced wall clearance. If you aren't offered accessory shields for your stove or if you want to reduce the clearance even further, you can buy effective wall and ceiling shields or have them built.

    You can safely reduce the clearances for both certified and uncertified stoves by following the rules set out in standard CSA B365. The common feature of the clearance reduction rules is air space behind the shield material. This space sets up a convection flow of air when the stove is operating and prevents the stove's heat from reaching the wall. (The percentage shown in the following table is the amount by which you can reduce the lowest clearance with the particular shield system listed.) By using heat shields, you can reduce wall and ceiling clearances.”

    Adjusting to USA standards 36” not Canada’s 48” would allow 24 gage steel heat shields to reduce that distance 1/3 or 24 “

    All forum googlers posters please search for manufactured shields and specs and add the info to this post. This question keeps re occurring ?

    Mantle heat shields
    I have found one manufacturer that makes them and actually had the tested and the following information is from their web site.
    There are codes that govern distances in relationship to the amount the mantle protrudes with the use of a heat shield. The reduction goes like this 6” protrusion with heat shield reduces the distance to 12” 8” protrusion 16” and 10” protrusion 20 “


    HomeSaver Mantel Shield - This 24-ga., black HomeSaver Mantel Shield attaches to the mantel and allows a clearance reduction from 18" to 9" from stovepipe and from 36" to 18" from the top of an unlisted stove. (For listed stoves, consult stove manual or manufacturer.) Our mantel shield is 47" wide, has a depth or "face" of 10", and the angled lip is 2 3/4" wide. It can be cut to size and comes predrilled and ready to mount. All necessary ceramic spacers, hardware, and instructions are included.
  2. drizler

    Minister of Fire 2.

    Nov 20, 2005
    Chazy, NY 12921
    And while you are at it don't buy that steel in the wrong place. You will hemmorage to death via the wallet if you buy it at a hardware store or stove shop. You can buy it at the local steel fab shop or sheet metal shop for much less than half price. You can get it a lot cheaper yet if you don't mind cleaning up the rust by going to the local scrap yard. Something like .30 / lb. Some landfills and dumps even sell scrap metal.
  3. elkimmeg

    Guest 2.

    good advice Automobile hoods and trunk lids would work
  4. babalu87

    New Member 2.

    Nov 23, 2005
    middleborough, ma.
    We have a Morso 3610 and wanted the footprint of the hearth and stove to be as small as possible with safety being the number one factor.
    Morso stoves have bottom and rear heat shields

    I checked with my towns inspector (he is probably as knowledgeable as you Elk) and he told me what he wanted and this is how I did the install (2 x 4 construction with 1/2" sheetrock is the existing wall) :

    1/2" durock (concrete board) on 1" aluminum spacers (bottom airspace as well) attached to the wall the width of the hearth pad
    I built the hearth pad using 3/4 plywood as a base (for strength and to limit flexing)
    Then a sheet of Micore 300 topped with concrete board and then porcelain tile.
    The specs on the hearth pad exceed twice the values recommended by Morso

    The stove is within 6" of the concrete board and the rear wall protection extends above the stove top by about 10"
    I also have a stovepipe heat shield on the single wall stove pipe that goes up to the class A connector and out the rear of the house.
    The concrete board really never gets warm and I can put my hand on the back of the stove at the highest temp I have had the stove fired to (550 stack temp! and that wasnt on purpose)

    I have no concerns with the safety aspect of the install and neither did the inspector who has been checking wood stove installs for almost as long as I have been alive (39)

    MOST manufacturers provide clear instructions on installations, thats why they give you a manual with the stove

    Probably more than you wanted :red:
  5. elkimmeg

    Guest 2.

    The post is not aimed at any one, but meant to braod spread informational,of possible ways clearance can be safetly reduced
  6. tickbitty

    Minister of Fire 2.

    Feb 21, 2008
    Just bumping this because I think there might be some folks (in addition to myself) dealing with this issue. Thanks
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