EPA Wood Stove Certification Data Sheet How they measure the firebox

elkimmeg Posted By elkimmeg, Jan 23, 2006 at 5:59 PM

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  1. elkimmeg

    Guest 2.

    This should help one understand how the testing is done and what is involved including fire box measurements

    EPA Wood Stove Certification Data Sheet

    The testing of wood stoves for EPA certification conducted by Intertek is done following EPA Methods 28 and 5G-3. Below is a short description of terms and procedures.

    >> The emissions rate is the weight of particulates emitted into the flue gas over a given period.

    >> The weighted average emission rate balances the emissions according to the burn rate of the wood.

    >> Catalytic stoves must have a weighed emissions rate of 4.1 grams per hour or less, while non-catalytic stoves must have a weighted emission rate of 7.5 grams per hour.

    >> The stove is tested at 4 different burn rates:
    >> Category 1 = Less than .8 kg/hr; Less than 1 kg/hr if the control is in the full closed position
    (Dry wood burn rates = amount of wood minus the moisture content divided by time burned)
    >> Category 2 = .8 kg/hr – 1.25 kg/hr
    >> Category 3 = 1.25 kg – 1.9 kg/hr
    >> Category 4 = 1.9 kg/hr or more (all controls on the unit must be at its highest burn rate position)

    >> The fan is run on high for all runs unless specified differently in the owner’s manual.

    >> Optional fans require another run category with the fan off.

    >> The unit is placed on a platform scale. Single wall pipe is installed to 8’6”± 6” above the scale platform with insulated chimney extending it to 15’± 1’.

    >> The firebox volume is calculated using your production drawings. The calculated volume multiplied by 7 is the test fuel load weight (± 10%). Air-dried Douglas Fir with moisture content between 19 and 25% (dry basis) is cut to 5/6 the largest length of the firebox.

    >> If the firebox volume is:
    >> <1.5 cu. ft. use all 2x4’s
    >> 1.5 to 3 cu. ft. use half the weight in 2x4’s and the rest 4x4’s
    >> >3 cu. ft. use all 4x4’s

    >> Douglas Fir spacers (3/4” x 1-1/2” x 5”) are placed at the ends (top and bottom) of test load pieces.

    >> A fire is started with kindling and paper. A preload consisting of 2x4’s at least 1/3 the length of the test load pieces and roughly the weight of the test load is then placed in the stove. The air controls may be adjusted, the door open or the coal bed raked during the preburn. At least 1 hour before the test load is inserted the air controls may not be adjusted. The coal bed may be stirred at any time until 15 minutes before the test run. During the last 15 minutes of the preburn the door can only be open for 1 minute to rake the coal bed.

    >> The test load is inserted when the weight of preload in the stove is 20 to 25% of the test load weight. The scale is adjusted so that the weight is at 0 pounds. The test load is then loaded in the stove within 1 minute. During the first 5 minutes of the test the air controls, fan, and door may be adjusted according to the manufacturers written instructions. After 5 minutes nothing can be adjusted until the end of the test is reached. This occurs when the weight of the wood has returned to 0 pounds. (One stir is allowed after 60% of the test load has burned and the test load weight has not changed .1 pound or 1% of the test load over a 10-minute period, but the door may be open only for 15 seconds during the stir).

    >> Continuously during the test a portion of the flue gas is pulled through a filter collection system. Every 10 minutes a reading is taken of CO, CO2, O2, stove temperatures (the average of the five firebox surface temperatures may only vary ± 125 degrees between the start and finish of the test), gas sample rates, tunnel velocity, stack temperature, tunnel temperatures and dry gas meter readings. These readings provide the proportional flow rate between the tunnel and the collection system. This data is also used for the calculation of the efficiency of the unit following CSA Standard B415. The final grams per hour are calculated after weighing the filters.
    More info EPA http://www.epa.gov/woodstoves/technical.html
  2. BrotherBart

    Hearth.com LLC Mid-Atlantic Division 2.
    Staff Member

    Nov 18, 2005
    Northern Virginia
    Yep, that's pretty much how we burn at my house too.
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