Installation Manual

Demand Duo™ H-Series Installation and Operation Manual 28
For applications containing corrosive indoor air,
this appliance must be installed as direct vent.
DO NOT use room air in applications where
combustion air contains acid forming chemicals
such as sulfur, fluorine and chlorine. These
chemicals have been found to cause rapid
damage and decay and can become toxic when
used as combustion air in gas appliances. Such
chemicals can be found in, but not limited to
bleach, ammonia, cat litter, aerosol sprays,
cleaning solvents, varnish, paint and air
fresheners. Do not store these products or similar
products in the vicinity of this water heater.
Unconfined Space
An unconfined space is defined in National Fuel
Gas Code, ANSI Z223.1/NFPA 54 as “a space
whose volume is not less than 50 cubic feet per
1000 Btu/hr (4.8 m3 per kW per hour) of the
aggregate input rating of all appliances installed
in that space. Rooms communicating directly with
the space in which the appliances are installed,
through openings not furnished with doors, are
considered a part of the unconfined space.” If the
“unconfined space” containing the appliance(s) is
in a building with tight construction, additional
outside air may be required for proper operation.
Outside air openings should be sized the same
as for a confined space.
This water heater requires adequate combus-
tion air for ventilation and dilution of flue gas-
es. Failure to provide adequate combustion
air can result in unit failure, fire, explosion,
serious bodily injury or death. Use the follow-
ing methods to ensure adequate combustion
air is available for correct and safe operation
of this water heater.
WARNING
Combustion Air
Non-Direct Vent (Room Air)
2
Combustion air must be free of corrosive
chemicals. Do not provide combustion air
from corrosive environments. Appliance
failure due to corrosive air is not covered by
warranty.
IMPORTANT
If ducts are used, the cross sectional area of
the duct must be greater than or equal to the
required free area of the openings to which
they are connected.
NOTE
Confined Space
A confined space is defined in the National Fuel
Gas Code, ANSI Z223.1/NFPA 54 as "a space
whose volume is less than 50 cubic feet per
1000 Btu/hr (4.8 m3 per kW per hour) of the ag-
gregate input rating of all appliances installed in
that space." Examples include a small room,
closet, alcove, utility room, etc. A confined space
must have two combustion air openings. Size
the combustion air openings based on the BTU
input for all gas utilization equipment in the
space and the method by which combustion air
is supplied.
Using Indoor Air For Combustion:
When using air from other room(s) in the build-
ing, the total volume of the room(s) must be of
adequate volume (Greater than 50 cubic feet per
1000 Btu/hr). Combustion air openings between
joining rooms must have at least 1 square inch
of free area for each 1000 Btu/hr, but not less
than 100 square inches each.
Using Outdoor Air For Combustion
Outdoor air can be provided to a confined space
through two permanent openings, one com-
mencing within 12 in. (0.30 m) of the top and
one commencing within 12 in. (0.30 m) of the
bottom, of the confined space. The openings
shall communicate to the outside by one of two
ways.
When communicating directly with the outdoors
through horizontal ducts, each opening shall
have a minimum free area of 1 in
2
/2000 Btu/hr
(1100 mm
2
/kW) of total input rating of all appli-
ances in the confined space.