John Wood Atmospheric Gas (Standard) - Manual (Page 11)

11
TABLE 1
BTU/HR (kW)
Input
Minimum Square
Feet
(Square Metres)
with 8 Foot
(2.44 Metre)
Ceiling
Typical Room
with 8 Foot
(2.44 Metre)
Ceiling
30,000 (8.79) 188 (17.47) 9’ x 21’ (2.7 m x 6.4 m)
45,000 (13.18) 281 (26.10) 14’ x 20’ (4.3 m x 6.1 m)
60,000 (17.58) 375 (34.84) 15’ x 25’ (4.6 m x 7.6 m)
75,000 (21.97) 469 (43.57) 15’ x 31’ (4.6 m x 9.4 m)
90,000 (26.37) 563 (52.30) 20’ x 28’ (6.1 m x 8.5 m)
105,000 (30.76) 657 (61.04) 20’ x 33’ (6.1 m x 10.1 m)
120,000 (35.15) 750 (69.68) 25’ x 30’ (7.6 m x 9.1 m)
135,000 (39.55) 844 (78.41) 28’ x 30’ (8.5 m x 9.1 m)
IMPORTANT:
•
The area must be open and be able to provide the
proper air requirements to the water heater. Areas that
are being used for storage or contain large objects
may not be suitable for water heater installation.
• Water heaters installed in open spaces in buildings
with unusually tight construction may still require out-
door air to function properly. In this situation, outside
air openings should be sized the same as for a con-
fined space.
• Modern home construction usually requires supplying
outside air into the water heater area.
Confined Space
For the correct and proper operation of this water heater,
ample air must be supplied for the combustion, ventilation,
and dilution of flue gases.
The size of openings (free areas) is determined by the total
BTU/HR input of all gas utilization equipment (i.e., water
heaters, furnaces, clothes dryers, etc.) and the method
by which the air is provided. The BTU/HR input can be
found on the water heater rating plate. Additional air can be
provided by two methods:
1. All air from inside the building.
2. All air from outdoors.
All Air from Inside the Building
When additional air is to be provided to the confined area
from additional room(s) within the building, the total volume
of the room(s) must be of sufficient size to properly provide
the necessary amount of fresh air to the water heater
and other gas utilization equipment in the area. If you are
unsure that the structure meets this requirement, contact
your local gas utility company or other qualified agency for
a safety inspection.
When indoor air is used, small enclosures and confined
areas must have two permanent openings so that sufficient
fresh air can be drawn from outside of the enclosure. The
bottom opening must be no lower than 6 inches (150 mm)
and no more than 18 inches (45.7 cm) above floor level.
The top opening must have the same area as the bottom
opening and be located as close to the ceiling as possible.
COMBUSTION AIR & VENTILATION
Carbon Monoxide Warning
Follow all the local and provincial codes or, in the
absence of local and provincial codes, the “Natural Gas
and Propane Installation Code,” CSA B149.1-current
edition to properly install vent system.
Failure to do so can result in death, explosion, or
carbon monoxide poisoning.
WARNING
IMPORTANT: Air for combustion and ventilation must not
come from a corrosive atmosphere. Any failure due to
corrosive elements in the atmosphere is excluded from
warranty coverage.
The following types of installation (not limited to the
following) will require outdoor air for combustion due to
chemical exposure and may reduce but not eliminate the
presence of corrosive chemicals in the air:
• beauty
shops
• photo processing labs
• buildings with indoor pools
• water heaters installed in laundry, hobby, or craft
rooms
• water heaters installed near chemical storage areas
Combustion air must be free of acid-forming chemicals such
as sulfur, fluorine, and chlorine. These elements are found
in aerosol sprays, detergents, bleaches, cleaning solvents,
air fresheners, paint, and varnish removers, refrigerants,
and many other commercial and household products. When
burned, vapors from these products form highly corrosive
acid compounds. These products should not be stored or
used near the water heater or air inlet.
Combustion and ventilation air requirements are determined
by the location of the water heater. The water heater may
be located in either an open (unconfined) area or in a
confined area or small enclosure such as a closet or small
room. Confined spaces are areas with less than 50 cubic
feet for each 1,000 BTU/HR (4.8 cubic metres per kilowatt)
of the total input for all gas-using appliances.
Unconfined Space
A water heater in an unconfined space uses indoor air for
combustion and requires at least 50 cubic feet for each
1,000 BTU/HR (4.8 cubic metres per kilowatt) of the total
input for all gas appliances. The following table shows a
few examples of the minimum area required for various
BTU/HR inputs.