4
Pre-Installation Items
Ventilation and Combustion Air Requirements -
Direct Vent
A Direct Vent appliance utilizes uncontamined outdoor
air (piped directly to the appliance) for combustion.
For Direct Vent installations involving only the MODU-
LATING DELTA, the space / enclosure must provide two
openings for ventilation. The openings must be sized to
provide 1 square inch of free area per 1,000 BTUH of
appliance input. The openings shall be placed 12 inch-
es from the top of the space and 12 inches from the floor
of the space.
For installations in which the MODULATING DELTA
shares the space with air movers (exhaust fan, clothes
dryers, fireplaces, etc.) and other combustion equip-
ment (gas or oil) the space must be provided with ade-
quate air openings to provide ventilation and combus-
tion air to the equipment. To properly size the ventilation
/ combustion air openings, the installer must comply
with the National Fuel Gas Code NFPA 54, ANSI Z223.1
for installations in the U.S or CSA B149.1 and B149.2 for
installations in Canada.
The space must be provided with ventilation /
combustion air openings properly sized for all
make-up air requirements (exhaust fans, clothes
dryers, fireplaces, etc.) and the total input of all
appliances located in the same space as the
MODULATING DELTA, excluding the input of a
Direct Vent MODULATING DELTA which uses
combustion air directly from the outside, thus
additional free area for the openings is not
required. Failure to provide or properly size the
openings could result in severe personal injury,
death or substantial property damage.
WARNING
Ventilation and Combustion Air Requirements -
Category I, III and IV
A Category I, III and IV appliance utilizes uncontaminat-
ed indoor or outdoor air (surrounding the appliance) for
combustion.
In order to reduce the potential risks associated
with indoor contaminates (listed on page 3),
flammable vapors and tight housing construc-
tion (little or no infiltration air), it is recommend-
ed to pipe uncontaminated combustion air
directly from the outdoors to the appliance. This
practice also promotes higher system efficiency
by reducing heated indoor air from being
exhausted from the house and replaced by cold
infiltration air into the house.
For installations in which the MODULATING DELTA
shares the space with air movers (exhaust fan, clothes
dryers, fireplaces, etc.) and other combustion equipment
(gas or oil) the space must be provided with adequate
air openings to provide ventilation and combustion air to
the equipment. To properly size the ventilation / com-
bustion air openings, the installer must comply with the
National Fuel Gas Code NFPA 54, ANSI Z223.1 for
installations in the U.S or CSA B149.1 and B149.2 for
installations in Canada, as referenced in this section of
the manual and title Methods of Accessing Combustion
Air into a Space.
The space must be provided with ventilation /
combustion air openings properly sized for all
make-up air requirements (exhaust fans, clothes
dryers, fireplaces, etc.) and the total input of all
appliances located in the same space as the MOD-
ULATING DELTA. Failure to provide or properly
size the openings could result in severe personal
injury, death or substantial property damage.
WARNING
BEST PRACTICES
