Combination of Indoor and Outdoor
Combustion Air
Indoor Openings: Where used, openings con-
necting the interior spaces shall comply with
the Indoor Combustion Air section on page 8.
Outdoor Opening(s) Location. Outdoor open-
ing(s) shall be located in accordance with the
Outdoor Combustion Air section.
Outdoor Opening(s) Size. Outdoor opening(s)
shall be calculated in accordance with the fol-
lowing:
- The ratio of the interior spaces shall be
the available volume of all communi-
cating spaces divided by the required
volume.
- The outdoor size reduction factor shall
be 1 minus the ratio of interior spaces.
- The minimum size of outdoor open-
ing(s) calculated in accordance with the
above outdoor air section multiplied by
the reduction factor. The minimum
dimension of air openings shall not be
less than 3 in.
Vent System
The PERFORMANCE is designed to vent
as a Category I appliance using standard
gas vent or, as a Category III appliance,
which requires a special vent system.
Category III Venting is described as a vent
system that has a positive static pressure
and a flue temperature that avoids exces-
sive condensate within the vent.
10
Combustion Air and Venting
Equipment Located in Confined
Spaces; All Air from Outdoors
Through Ventilated Attic
Fig. 3:
Equipment Located in Confined
Spaces; All Air from Outdoors
Fig. 4: