Draft: ASTM Test-Fueling Protocol for Masonry and Special-Design Fireplaces

Draft: ASTM Test-Fueling Protocol for Masonry and Special-Design Fireplaces

Draft: ASTM Test-Fueling Protocol for Masonry and Special-Design Fireplaces

May 15, 2007


1.1Applicability and Principal. The test-fueling procedures and specifications prescribed by this Standard Practice are for use when measuring emissions from, and the thermal performance of residential wood-burning masonry and special-design fireplaces. This Standard Practice includes specifications for test-period duration, test fuel specifications, test fueling procedures, fireplace operations, and data-recording requirements. The methods and procedures prescribed by this Standard Practice are performed on masonry and special-design fireplaces installed in accordance with their builder’s and/or manufacturer’s specifications. Specified flue-gas temperature criteria are used to initiate a test period and flue-gas carbon dioxide plus carbon monoxide (CO2+CO) concentration criteria are used for determining fuel re-charging times and test period completion. Combustion gases sampled at a standardized sampling location and analyzed for CO2+CO concentrations may also be used for calculating mass-balance flue-gas flow rates which can then be used for calculating emissions factors and rates.

2.0 Definitions

Masonry and Special-DesignFireplaces—are masonry or metal structureswith a cavity within which wood fuel is placed and burned. Masonry and special-design fireplaces are exempt from Title 40 of the Code of Federal Regulations (CFR) Part 60, Subpart AAA and are not cookstoves, boilers, furnaces, pellet stoves as defined in 40CFR60 Subpart AAA or “low-mass” fireplaces as defined in ASTM ????. Masonry and special-design fireplaces can be operated:

1. with a fire screen and/or glass doors in place over the fuel-loading and fire-viewing opening (ie, closed-door configuration) or

2. with the fuel-loading and fire-viewing opening open, without obstruction, and in free communication with the surrounding atmosphere (ie, open-door configuration).

Masonry and special-design fireplaces may be factory- or site-built. Masonry fireplaces are characterized by being constructed primarily from high-density masonry or cast cement materials. Masonry fireplaces typically utilize cast metal, wrought metal, and/or fabricated sheet metal grates, door frames, lintel supports, dampers, and/or factory-built metal chimneys.

Flue-Gas Exhaust Duct— the connector pipe, chimney, or other duct form that conveys exhaust gases from the masonry and special-design fireplace firebox to the outdoor atmosphere. Flue-gas exhaust duct cross-sectional area is calculated using duct dimensions measured at the narrowest point downstream from the horizontal plane which intersects the top most edge of the fuel loading door (See definition for "Firebox Height" under “Usable Firebox Volume”).

Fuel-Elevating Grate— a non-combustible structure capable of elevating a fuel load above the hearth of a masonry and special-design fireplace while offering no, or very little impedance to the passage of combustion air supplies to the bottom of the fuel load and up through the fuel load.

Fuel-Elevating Grate Height— is the fuel elevation height above the hearth; the distance between the hearth and a horizontal plane at the bottom of an elevated fuel load.

Fuel: Total Weight —the total weight of the fuel pieces to be used in each fuel-load crib plus spacer and kindling weight.

Hearth Dimensions

Primary Horizontal Hearth Dimension (PHhd)— for all hearth shapes, the length of a line drawn within the hearth perimeter that is: 1. either a line of hearth plan-view symmetry or the longest line that can be drawn within the hearth perimeter perpendicular to a plan-view line of symmetry and 2. the axis parallel to which fuel-piece lengths are oriented for testing. The masonry and special-design fireplace manufacturer or builder shall designate the PHhd, choosing either a line of symmetry or the longest line that can be drawn perpendicular to a line of symmetry, whichever is to be the axis line along which fuel piece lengths are oriented in parallel for burning.

Non-symmetrical hearth shapes—the PHhd shall be designated in accordance with the objective of making fuel piece orientation reflect the basic length and width orientation of the hearth within the space intended for fuel placement and burning.

Secondary Horizontal Hearth Dimension (SHhd) — for all hearth area shapes the length of the longest line that can be drawn within the hearth perimeter perpendicular to the designated PHhd.

Multiple Lines of Symmetry— Hearth shapes may have more than one line of symmetry to choose from. The SHhd associated with one PHhd and line of symmetry may not be used for calculating fuel crib dimensions with a PHhd based on a different line of symmetry.

Note: For square and full-circle hearth shapes, the PHhd and SHhd are of equal length.

Horizontal Flue-Gas Pathway— the total net horizontal-duct centerline distance measured from the point where the vertical centerline of the flue-gas exit duct from the firebox intersects the horizontal plane of the firebox height (See definition for "Firebox Height" under “Usable Firebox Volume”) to the point where the centerline of the exhaust duct exit to the atmosphere intersects the horizontal plane at the total vertical extent (i.e., height) of the exhaust duct at the flue-gas exit to the atmosphere. For the purpose, horizontal shall mean any amount of duct centerline traverse that is created by any angle which is either more or less than 90º or 270º from vertical.

Internal Assembly— the core construction and firebox design factors that may affect a masonry and special-design fireplace’s combustion function or particulate emissions factor.

Test-Fuel Charge— one of three test-fuel cribs burned during a test period.

Test-Fuel Loading Factor— the ratio between test-fuel crib volume including inter-fuel-piece spacing, and the usable firebox volume. For this Standard Practice, the test-fuel loading factor for masonry fireplaces is 0.15.

Usable Firebox Volume (Fv) — the product of the useable hearth area and the average useable height. Useable means the volumetric space within the fire chamber of a masonry and special-design fireplace into which fuel can be, or is intended to be, placed for firing. Usable firebox volume is calculated using the following dimensional definitions:

Firebox Length— average length of at least 9 equally spaced lines running parallel to the greater of 1. the PHhd, or 2. the SHhd.

Firebox Width or Depth — average length of at least 9 equally spaced lines running perpendicular to the lines used for determining firebox length.

Firebox Floor Versus Hearth Area— If a masonry and special-design fireplace has a larger floor area within the fire chamber than the area upon which it is intended that fuel be placed and burned, the useable hearth area shall be calculated as the sum of standard geometric areas or sub-areas of the area intended for fuel placement and burning.

Firebox Height (Fbh)— the vertical dimension measured from the hearth of a the top of a fuel-elevating grate to the horizontal plane that intersects and is perpendicular to the top edge of the fuel loading door opening.

Fuel-Elevating Grates— For masonry and special-design fireplaces with grates that elevate fuel charges above the hearth, the useable firebox area includes all geometric sub-areas within the total grate area or "foot print" circumscribed by the connection of all of the outer most grate projections. Useable hearth areas calculated using fuel-elevating grate dimensions shall be multiplied by a factor of 1.5 for determining fuel load charge volumes. The volume of test-fuel charges calculated using fuel-elevating grate areas shall not exceed the volume of test-fuel charges determined for the masonry and special-design fireplace hearth area.

3.1Test Fuel

3.1.1Species. Test fuel shall be Douglas fir.

3.1.2Fuel Piece Cross-Sectional Dimensions. Test fuel pieces shall consist of air-dried1.5- by 3.5-inch (51- by 89-mm) and 3.5- by 3.5-inch (89- by 89-mm) actual-dimension lumber.

3.1.3Fuel Moisture Content. For each fuel piece fuel moisture content is the average of 1-inch deep moisture measurements made at three locations on each piece; one each not closer than 2.0 inches (51 mm) from each end of each fuel piece and one near the longitudinal middle of each fuel piece. The average fuel moisture of each piece shall be in the range of 19 to 25% dry basis (16 to 20% wet basis).

Note: Most wood moisture meters measure in dry-basis percent. Verify the moisture meter specifications to confirm its moisture basis output measurement type.

3.1.4Test-Fuel Cribs. Fuel-load cribs shall be constructed so that their length,

width, and height are equally proportional to the average length, width, and height of the firebox of the masonry fireplace being tested. Three separate fuel-load cribs shall be prepared. The first layer of the first fuel crib load shall be made up of 1.5- x 3.5-inch (38- x 89-mm) fuel pieces. The second and higher layers of the first fuel crib load and the second and third fuel crib loads are made entirely of 3.5- x 3.5-inch (89- x 89-mm) fuel pieces. Fuel Crib Construction. Fuel cribs with component and

construction specifications different from those prescribed herein may be approved at the discretion of regulatory jurisdictions specifying this Standard Practice for regulatory purposes. Alternative fuel crib designs that may be considered include those typically referred to as “tepee”, “top-down”,“rack- or grate-supported full-face”, and/or “air-injection-grate or “rack” burning configurations. Any alternative fuel crib design shall have some means to ensure fuel load stability for three consecutively placed or loaded alternative fuel crib designs. For example, all of the fuel pieces in each consecutively loaded tepee-design fuel crib, shall reasonably remain in the tepee position, without any fuel pieces falling out of the primary combustion zone during a test period. Also, the second and third alternative fuel-crib loads shall be placed upon the precedent fuel-load coal bed. It must be demonstrated that the second and third fuel-crib loads areeasily and safely placed in the combustion zone by fireplace users. Alternative fuel-crib designs shall also consist of the same volume/volume fuel loading factor and fuel-piece size distributions as fuel-crib loads derived from the no-grate hearth area specified in 3.1.5. Spacer-Ties. To tie all of the fuel pieces in each fuel crib layer together, a single, 0.625-x1.5-inch (16-x38-mm), woodenstripshall run laterally towardeach end of the bottom of each fuel crib layer andcoincident with the fuel crib depth.The length of each of these fuel-crib-layer ties, shall run to within 1 inch (25 mm) of the outer edge of the outer fuel pieces of the fuel crib. Fuel-Piece Spacers. Vertical spacers measuring 0.625 x 1.5 x 2.0 inches, shall becentered between and on all fuel-piece sidesthat face another fuel piece side and on the outer fuel-piece sides that face away from the viewing side of the fireplace firebox (ie, those fuel-piece sides that typically face the back wall (“fire-back”) of the firebox). No vertical spacers are to be placed on any other outward-facingfuel-piece sides (ie, the top and front). See Figures,, and

Figure First Fuel-Crib Load Details.

Figure Second and Third Fuel Crib Details.

Figure Fuel Piece Spacer Placement.

3.1.5Fuel Crib Dimensional Specifications. This section describes the procedure by which fuel crib dimensional specifications are determined for hearth perimeters delineated by at least 3 straight-line walls/sides around the hearth and hearth perimeters having at least one horizontal line of symmetry across the hearth. Crib Shape. Except as specified in, all fuel cribs built to the specifications of this section will have rectilinear plan and length views. and Secondary Horizontal Hearth Dimension Designation. The manufacturer or builder shall designate either the line of horizontal symmetry or the longest line drawn perpendicular to the horizontal line of symmetry as the PHhd along which the length of the fuel crib shall be oriented for burning. The longest line perpendicular to the PHhd is designated as the Secondary Horizontal Hearth Dimension (SHhd). of Symmetry. A line of symmetry is obtained by drawing a straight line across a plan-view drawing of the hearth area, or, if present, the fuel elevating grate area so that the line bisects the hearth or fuel-elevating grate area into mirror images. For hearth or fuel-elevating grate areas that have more than one line of symmetry, only one shall be chosen as the PHhd. This standard makes no preference or specification of which one is chosen. PHhd. Determine the average PHhd from the lengths of at least 9 lines equally spaced and parallel to the PHhd along the whole length of the SHhd. SHhd. Determine the average SHhd from the lengths of at least 9 lines equally spaced and parallel to the SHhd along the whole length of the PHhd. Firebox Height (Fbh).If there are inwardly slanted or curved firebox walls or other downward physical projections, an average firebox height shall be determined using vertical dimensions measured from the hearth or top of a fuel-elevating grate to the horizontal plane that intersects and is perpendicular to the top of the fuel loading door opening or any lower projection directly above the centers of at least 9 closely-equal and square hearth sub-areas, none of which exceeds 16 inches2 (100 cm2). Height-to-Width Ratio Limitation. The average-Fbh/average-SHhd ratio shall not exceed 1.1:1.0. If the average-Fbh/average-SHhd ratio is greater than 1.1:1.0, the average Fbh shall be reduced to 110% of the average-SHhd. This adjusted average-Fbh (Fbha) shall be substituted for Fbh in all of the following fuel-crib dimensional calculations. Useable Hearth Area. Determine the total usable hearth area (Hua) or, if present, the total horizontal plan area of the fuel-elevating grate. Firebox Volume (Fv). Calculate useable firebox volume by multiplying the average Fbh (or, if applicable, the Fbha) by Hua. Firebox Volume. If the calculated firebox volume

of the masonry fireplace being tested is greater than 7.0 ft3 (0.2 m3), the fireplace shall be tested twice: once using fuel cribs based on the actual, as measured, firebox volume, and once using fuel cribs based on a firebox volume of 5.0 ft3 (0.14 m3). Emissions or thermal performance measurements made during each of these two test-burn periods shall be averaged when results are reported. Volume. Calculate the fuel-crib volume (Fcv) as 15% of the Fv. Grate. Fuel-crib volume calculated from a fuel-elevating-grate-based Hua (see Fuel-Elevating Grate under the Firebox Volume definition in 2.0) shall not be greater than the fuel-crib volume calculated using an Hua derived from the whole useable hearth area. Sizing Factor (FCdsf). Determine the fuel-crib-dimension/firebox-dimension sizing factor as the cube root of the fuel-crib-volume/firebox-volume loading factor “X”.


Where:X = 15.0% for fireplaces using the whole usable hearth area, or

X = 22.5% for fireplaces using the fuel-elevating grate area (See (ie, fuel-piece) Length (FCl), Target Fuel Crib Width (FCtw), and Target Fuel Crib Height (FCth). Determine FCl, FCtw, and FCth using the following equations:

FCl = PHhd x FCdsfEquation

FCtw = SHhd x FCdsfEquation

FCth = FBh x FCdsfEquation

3.1.6Fuel Piece Spacing.

Standard Rectilinear Fuel Cribs. The 0.625-inch (16-mm) thick vertically-positionedspacers and the horizontally-positionedinter-piece ties shall be secured by nailing, with 18-gage by 1¼-inch (32-mm) finishing brads. The 0.625-inch by 1.5-inch by 2.0-inch (16-mm by 38-mm by 51-mm) spacers shall be positioned so the longitudinal centerline of their 1.5-inch x 2.0-inch (38-mm x 51-mm) surface is ‘X’ inches from and parallel to the 3.5-inch (89 mm) end edge of the fuel piece to which it is being attached: where X = 0.15 x Fpl. These vertically-positionedfuel-piece spacers are further positioned so the latitudinal centerline of the 1.5-inch x 2.0-inch (38-mm x 51-mm) surface of the spacer is perpendicular to, and 1.75 inches (45 mm) from the edge at the longitudinal end of the fuel piece to which it is being attached. 0.625-inch x 1.5-inch x the fuel-crib-width fuel crib layer ties shall also be positioned 1.75 inches (45 mm) from the end edges of the fuel pieces being connected together into fuel-crib layers or parts of layers. The fuel piece ties may be made to connect 2, 3, 4 or more fuel pieces together at the discretion of the tester. The objective of the horizontal ties is to make the fuel crib more stable when it is in place in the fireplace and being burned. However, if loading whole multiple-fuel-piece layers causes unsafe operator conditions, the number of pieces tied together may be reduced. To maintain 0.625-inch (16-mm) vertical spacing between all fuel pieces, spacers are only be attached on alternating facing fuel-piece sides and no fuel piece ties are to be positioned on the bottom of the fuel-crib bottom layer and on the top of the top layer. Maximum spacing between all fuel pieces shall not exceed 0.625 inches (16 mm).

Teepee Fuel Stack Configuration. Where a teepee fuel stack configuration is approved, the 1.5-inch x 2-inch (38-mm x 51 mm) fuel-piece spacers may beturned so the longitudinal centerline of the 1.5-inch x 2.0-inch (38-mm x 51-mm) surface of the spacer is perpendicular to the end edge of the fuel piece to which it is attached. In addition, for a test burn fire, the fuel pieces shall be positioned in a near-vertical-oriented stack with one longitudinal end of each piece in contact with the hearth and the other end leaning on and supported by a specialty “teepee” grate in a direction towards the fireback of the fireplace. The first fuel crib pieces are loaded with the 1.5-inch x 3.5-inch pieces on the inner layer closest to the specialty grate structure.