Email from Jim Buckley, April 7, 1999

(private discussion snipped)

1) (snip)
In general the code is for site-built non proprietary construction - like the kind of
construction done by members of the MHA - and a listing of some sort is for
manufactured and proprietary products. (snip).

2) "Minimum fire and safety standards" really don't involve flue sizes,
efficiency or how many turns the flue channels take. The code committees
will be more interested in clearance to combustibles and seismic
reinforcing. Maybe the "compromise" should be to shorten the definition of
a masonry heater in the code and see it's purpose as one of identification
- not performance characteristics. Get all the controversial language out
of the code and deal with the finer points of the definition somewhere else.

The IBC Committee approved the "short version" which referenced ASTM E 1602
but does not mention flue size. It could be stripped down even more to
eliminate the words "heating appliance" "at least 180 degrees" and "the
surface temperature not to exceed 230 degrees". In the code, the
definition is just for identification purposes.

The IRC Committee, on the other hand, approved the "long version" which is
basically the whole ASTM E 1602 and does include the flue sizes and
anything else Walter might object to.

Since masonry heaters are in the IBC and IRC differently, it would be
appropriate for the MHA or MACS or even me (as the original proponent) to
quietly challenge the code change for the purpose of coordinating the
language between the two codes. They would especially like it if there was
less language. (snip)


Jim Buckley


2112.1 Definition. A masonry heater is a heating appliance constructed of
concrete or solid masonry, hereinafter referred to as masonry,
having a mass of at least 800 kg (1760 lbs.), excluding the chimney and
foundation, which is designed to absorb and store heat from a solid
fuel fire built in the firebox by routing the exhaust gases through
internal heat exchange channels in which the flow path downstream of the
firebox includes at least one 180 degree change in flow direction before
entering the chimney and which delivers heat by radiation from the
masonry surface of the heater which shall not exceed 230 degrees F (110
degrees C) except within 8 inches (203 mm) surrounding the fuel
loading door(s).

2112.2 Installation. Masonry Heaters shall be listed or installed in
accordance to ASTM E-1602

2112.3 Seismic reinforcing. Seismic reinforcing shall not be required
within the body of a masonry heater whose height is equal to or
less than 2.5 times it's body width and where the masonry chimney serving
the heater is not supported by the body of the heater. Where the
masonry chimney shares a common wall with the facing of the masonry heater,
the chimney portion of the structure shall be reinforced in
accordance with Section 2113.

2112.4 Masonry heater clearance. Wood or other combustible framing shall
not be placed within 4 inches (102 mm) of the outside
surface of a masonry heater, provided the wall thickness of the firebox is
not less than 8 inches (203 mm) and the wall thickness of the heat
exchange channels is not less than 5 inches (127 mm). A clearance of at
least 8 inches (203 mm) shall be provided between the gas tight
capping slab of the heater and a combustible ceiling. The required space
between the heater and combustible material shall be fully vented to
permit the free flow of air around all heater surfaces.