John Wood Power Vent 0.67 EF - Manual (Page 10)

Ventilated Space Air Requirements for
U.S. Installations
Refer to Figure 5 (a), (b), (c) or (d) for proper sizing and
location of combustion air ducts and openings. CHECK
LOCAL CODES.
a) Equipment located in ventilated spaces; all air from
inside the building.
Two permanent openings shall be provided connecting
to ventilated space (e.g. closet, small room) with the
unconfined space. Each opening shall be equal or
greater than 645cm
2 (100 in 2 .) with a width to height
ratio of 2:1. The top opening shall be located close to
the ceiling.
Note: The opening shall not be lower than the top of the
heater. The location of the bottom opening shall be 150-
450mm (6-18 in.) above floor level.
b) Basement installation, equipment located in ventilated
spaces; all air from outdoors.
Refer to the latest edition of the "National Fuel Gas
Code" ANSI Z223.1 for air supply duct sizes and
restrictions.
c) Equipment located in ventilated spaces; all air from out-
doors.
Refer to the latest edition of the "National Fuel Gas
Code" ANSI Z223.1 for air supply duct sizes and
restrictions.
d) Equipment located in ventilated spaces; all air from out-
doors through ventilated attic.
Refer to the latest edition of the "National Fuel Gas
Code" ANSI Z223.1 for air supply duct sizes and
restrictions.
Note: Ensure sufficient ventilation air to prevent elevat-
ed temperatures in closets and ventilated spaces.
When an exhaust fan is installed in the same room as the
water heater, the supply air openings must be of sufficient
capacity to prevent a backflow of air through the water
heater exhaust venting.
Burn Hazard
Do not touch vent.
Doing so can result in
burns.
– 10 –
VENTILATED
SPACE
PERMANENT
OPENINGS
EQUIPMENT LOCATED IN VENTILATED
SPACES; ALL AIR FROM INSIDE THE BUILDING.
(a)
UNCONFINED
SPACE
VENTILATED
SPACE
ATTIC LOUVERS TO OUTDOORS
EQUIPMENT LOCATED IN VENTILATED SPACES; ALL
AIR FROM OUTDOORS THROUGH VENTILATED ATTIC.
(d)
INLET AIR
DUCT
OUTLET
AIR
BASEMENT INSTALLATION, EQUIPMENT LOCATED
IN VENTILATED SPACES; ALL AIR FROM OUTDOORS
(b) VENTILATED
SPACE
GRADE
300mm
(12 in.)
300mm
(12 in.)
Figure 5 Combustion Air Supply Openings And Ducts
(U.S.A.)
COMBUSTION
AIR DUCT
PERMANENT
VENTILATION
AIR.
300mm
(12 in.)
ABOVE
GRADE
OR
SNOW
LINE
EQUIPMENT LOCATED IN VENTILATED
SPACES; ALL AIR FROM OUTDOORS.
(c)
VENTILATED
SPACE
COMBUSTION
300mm (12 in.)
300mm (12 in.)
300mm (12 in.)
OUTDOORS
AIR DUCT
VENTILATION