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FUTERA II INSTALLATION AND OPERATION INSTRUCTIONS
All Air From Inside The Building
If the Futera II is to be located in a confined space the
minimum clearances listed in Table 1 must be maintained
between it and any combustible construction. When
installed in a confined space without the intake air option
two permanent openings communicating with an additional
room(s) are required. The combined volume of these
spaces must have sufficient volume to meet the criteria for
an unconfined space. The total air requirements of all gas
utilization equipment, fireplaces, wood stoves or any type
of exhaust fan must be considered when making this
determination. Each opening must have a minimum free
area of 1 in2/1000 Btu/hr (2200 mm2/kW) based on the total
input rating of ALL gas utilization equipment in the confined
area. Each opening must be no less than 100 square
inches (64516 mm2) in size. The upper opening must be
within 12 inches (300 mm) of, but not less than 3 inches
(80 mm) from, the top of the enclosure.The bottom opening
must be within 12 inches (300 mm) of, but not less than 3
inches (80 mm) from, the bottom of the enclosure.
All Air From Outside The Building
When installed in a confined space without the intake air
option two permanent openings communicating directly
with, or by ducts to, the outdoors or spaces that freely
communicate with the outdoors must be present.The upper
opening must be within 12 inches (300 mm) of, but not less
than 3 inches (80 mm) from, the top of the enclosure. The
bottom opening must be within 12 inches (300 mm) of, but
not less than 3 inches (80 mm) from, the bottom of the
enclosure.
Where directly communicating with the outdoors or
communicating with the outdoors through vertical ducts,
each opening shall have a minimum free area of 1 in2/4000
Btu/hr (550 mm2/kW) of the total input rating of all of the
equipment in the enclosure.
Where communicating with the outdoors through hori-
zontal ducts, each opening shall have a minimum free area
of 1 in2/2000 Btu/hr (1100 mm2/kW) of the total input rating
of all of the equipment in the enclosure.
When ducts are used, they must have the same cross-
sectional area as the free area of the opening to which
they connect.
Table 2 – Make-up Air Duct Sizing
Required Cross Sectional Duct Area in2(cm2)
Input 1/4" (6.4 mm) Metal Wooden
(MBH) Wire Screen Louvers Louvers
500 125 (806) 167 (1077) 500 (3226)
750 187 (1206) 250 (1613) 750 (4839)
1000 250 (1613) 333 (2148) 1000 (6452)
1250 313 (2019) 416 (2684) 1250 (8065)
1500 375 (2419) 500 (3226) 1500 (9677)
1750 437 (2819) 583 (3761) 1750 (11,290)
1950 486 (3135) 649 (4187) 1950 (12,581)
When calculating the free area necessary to meet the
make-up air requirements of the enclosure, consideration
must be given to the blockage effects of louvers, grills and
screens. Screens must have a minimum mesh size of 1/
4" (6.4mm). If the free area through a louver or grill is not
known ducts should be sized per Table 2 above.
Intake Air Option – General Guidelines
This configuration provides combustion air directly to the
boiler/water heater’s air intake using a dedicated pipe when
using the direct vent option. The RBI air intake adapter
must be fitted to the blower inlet. Combustion air can be
drawn in horizontally through an outside wall or vertically
through the roof, see Figures 1, 2, 3 & 4.
WARNING
Each boiler/water heater must have it’s own intake air
system. Common intake air systems are not to be used!
Improper installation can result in excessive levels of
carbon monoxide which can cause severe personal injury
or death!
Single wall galvanized smoke pipe, single wall aluminum
pipe, flexible aluminum pipe, PVC or CPVC pipe can be
used for the intake air pipe. It must be sized per Table 3.
Table 3 – Intake Air Pipe Sizing
Model Size Pipe Diameter in2(mm2)
500 8 (203)
750, 1000 10 (254)
1250, 1500 12 (305)
1750, 1950 14 (356)
All joints in metal intake air systems must be secured using
corrosion resistant fasteners and sealed using a suitable
Silicone caulk. If PVC or CPVC is used, the joints must
be cleaned with a suitable solvent and connected using a
solvent based PVC cement. The intake air system MUST
be supported by the building structure not the boiler/
water heater.
A stack damper interlocked with the unit should be instal-
led in the intake air pipe when the infiltration of subfreez-
ing air could occur, otherwise the unit could freeze up.
Intake Air Option – Vertical Guidlines
The maximum equivalent length for the vertical intake air
pipe is 60 feet (19.7 m). Each 90˚ elbow and the intake
air cap are equal to 10 linear feet (3.3 m) of pipe.
A listed, nonrestrictive intake air cap must be used. The
intake air cap must terminate as shown in Figure 3. The
penetration point in the roof must be properly flashed and
sealed.
Intake Air Option – Horizontal Guidlines
The maximum equivalent length for the horizontal intake
air pipe is 60 feet (19.7 m). Each 90˚ elbow and the intake
air terminal are equal to 10 linear feet (3.3 m) of pipe. If
horizontal runs exceed 5 feet (1.5 m) they must be
supported at 3 foot (0.98 m) intervals with overhead
hangers. The certified intake air terminal from RBI must be
used, see Figures 1, 2 and 4.
