                            MYREN CONSULTING, INC.
                            512 WILLIAMS LAKE ROAD
                              COLVILLE, WA 99114
OFFICE: 509 684 1154        FAX: 509 684 3987
LAB:    509 685 9458   email: atmyren@gmail.com

DATE: 28 March 2011 

TO: Gil Wood

CC: Rod Zander, Tim Seaton

FROM: Ben Myren 

       RE: PROPOSED 2.0 G/HR DAILY AVERAGE STANDARD FOR MASONRY HEATERS

	The proposed 2.0 g/hr daily average standard for masonry heaters 
may not be the best way to look at this issue because the proposed standard appears to discriminate against large heaters. The daily average emission rate is affected by 4 things: (1.) the heater's performance, (2.) the test method used to measure heater performance, (3.) the firing interval used to determine the daily average and (4.) whether or not the correction factor used to convert M5G to M5H is used to adjust the emissions. Here some examples based upon typical numbers for a small and large unit, both having emission factors right at 1.0 g/kg when cordwood is being burned as fuel.

Small Unit (20-30 lbs. of fuel/ firing)
	Test Method		g/hr		Firing Interval	Daily Average

	CO Reg # 4		6.5			12 hours			0.542
	ASTM Crib			5.0			12  "			0.417
	Cordwood			3.0			12  "			0.285

Large Unit (40-60 lbs. of fuel/ firing)
      CO Reg # 4		12.0			12 hours			1.000
	ASTM Crib			N/A
	Cordwood			9.0			12  "			0.750

	A wood stove burning continuously at 4.5 g/hr and at 1 kg/hr would emit both 4.5 g/kg and 4.5 g/hr and in a 12 hour period would, depending upon its size, probably burn somewhere between 20 and 40 lbs of wood.  So its daily average would be 4.5 g/hr, which is significantly higher than any of the MH daily averages in the above examples.  Even if the emission factor were to increased to 2.5 g/kg  -  and the dry burn rate remained the same - the emission rate would still be below the proposed daily average for the small unit.  But the emission rate for the large unit would now be above the proposed standard.  However, if the firing interval were to be changed to 24 hours, the unit would remain in compliance.  Conversely, if the firing interval were to be changed to 8 hours, the emissions would change (increase).  So how the daily average standard is calculated will have a huge impact on whether or not units can be certified or not. 

      So in my mind the real question is, "Do we really need a daily average standard?"  If the emission factor is set at <=2.5 g/kg, then the issue of a daily average standard is not really important because the low emission factor insures a low emission rate.      

Let me know if you have any questions.

Regards, 

Ben Myren
