With all clearance reduction systems using ventilated air space there shall be at least 1” clearance
between the reduction systems using ventilated air space.
Mineral wool batts, blanket or board shall have a minimum density of 8lb/ft
3
and a minimum melting
temperature of 1500
0
F.
Insulation material used as part of a clearance reduction system shall have a thermal conductivity of
1.0(Btu/In)/ (Ft
2
/Hr/
0
F).
Table 2 Allowable Clearances with Specified Protection
Where the Specified Clearance with No Protection from the Appliance or
Chimney Connector
18” 12” 9” 6”
Type of protection applied to and
covering all surfaces within the distance
specified as the required clearance with
no protection
Above Rear
&
Sides
Above Rear
&
Sides
Above Rear
&
Sides
Above Rear
&
Sides
3½” thick masonry wall without
ventilated air space
N/A
12”
N/A
9”
N/A
6”
N/A
5”
½” insulation board over 1” glass fiber
or mineral wool batts
12” 9” 9” 6” 6” 5” 4” 3”
24 gauge sheet metal over 1” glass fiber
or mineral wool batts reinforced with
wire on rear face with ventilated air
space
9”
6”
6”
4”
5’
3”
3”
3”
3½” thick masonry wall with ventilated
air space
N/A 6” N/A 6” N/A 6” N/A 6”
24 gauge sheet metal with ventilated air
space
9”
6”
6”
4”
5”
3”
3”
2”
½” insulation board with ventilated air
space
9” 6” 6” 4” 5” 3” 3” 3”
24 gauge sheet metal with ventilated air
space over 24 gauge sheet metal with
ventilated air space
9”
6”
6”
4”
5”
3”
3”
3”
1” glass fiber or mineral wool batts
sandwiched between 2 sheets 24 gauge
sheet metal with ventilated air space
6” 6” 6” 4” 5” 3” 3” 3”
If the furnace is to be installed in a residential garage, the furnace must be a minimum of 18” above
the garage floor and located so it cannot be damaged by a moving vehicle
6
Summary of Contents for HBD1 15
Page 17: ...17 17...
Page 31: ...31...
