Demand Duo
™
R
-
Series Installation and Operation Manual
21
This water heater requires adequate combustion
air for ventilation and dilution of flue gases.
Failure to provide adequate combustion air can
result in unit failure, fire, explosion, serious bodily
injury or death. Use the following methods to
ensure adequate combustion air is available for
correct and safe operation of this water heater.
Combustion air must be free of 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.
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.
32 ft.
(9.7 m)
39 ft.
(11.8 m)
32 ft.
(9.7 m)
39 ft.
(11.8 m)
Note: 10 ft. Ceiling
Note: 10 ft. Ceiling
IMPORTANT
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.
Figure 10
32 ft. x 32 ft. x 10 ft. = 10,240 ft.
3
50 ft.
3
x
199,000 Btu/Hr
= 9,950 ft.
3*
1,000 ft.
*Required Volume for Unconfined Space (water
heater only)
39 ft. x 39 ft. x 10 ft. = 15,210 ft.
3
50 ft.
3
x
299,000 Btu/Hr
= 14,950 ft.
3*
1,000 ft.
*Required Volume for Unconfined Space (water
heater and a 100,000 BTU furnace)
