
FUTERA FUSION INSTALLATION AND OPERATION INSTRUCTIONS
4
All Air From Inside The Building
If the Futera 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, Figures
5, 6 and 7, 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 in2, 64,516 mm2in size. The upper opening must
be within 12 in,305 mm of, but not less than 3 in,
76 mm from, the top of the enclosure. The bottom opening
must be within 12 in, 305 mm of, but not less than 3 in,
76 mm from, the bottom of the enclosure.
All Air From Outside The Building
When installed in a confined space without utilizing 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 in, 305 mm of, but not
less than 3 in, 76 mm from, the top of the enclosure. The
bottom opening must be within 12 in, 305 mm of, but not
less than 3 in, 76 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 horizontal
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.
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 in, 6.4 mm. If the free area through a louver or grill is
not known, ducts should be sized per Table 2.
Canadian installations must comply with CSA B149.1 when
air supply is provided by natural air flow from the outdoors
for natural draft, partial fan-assisted, fan-assisted, or
power draft-assisted burners, there shall be a permanent
air supply opening(s) having a cross-sectional area of not
less than 1 in2per 7,000 Btuh (310 mm2per kW) up to
and including 1 million Btuh, plus 1 in2per 14,000 Btuh
(155 mm2per kW) in excess of 1 million Btuh.
Table 2 – Make-up Air Louver Sizing
Required Cross Sectional Area
Input 1/4 in 6.4 mm
75% Free Area
25% Free Area
(MBH) Wire Screen
Metal Louvers
Wooden Louvers
in2cm2 in2cm2 in2cm2
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
1999 500 3226 667 4303 2000 12,900
Intake Air Option – General Guidelines
This configuration provides combustion air directly to the
boiler/water heater’s air intake adapter using a dedicated
pipe when using the direct vent option. Combustion air can
be drawn in horizontally through the same outside wall
which terminates the exhaust gases or vertically through
the roof, see Figures 1, 2, 3 & 4.
WARNING: Common intake air systems may be
used provided the common duct is sized properly.
An intake combustion air damper should be
installed if the common vent option is used in the
intake air pipe of each heater. 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 For Vertical For Horizontal
Size (Up to 60') (Up To 60')
in mm in mm
500 8203 6152
750 8203 6152
1000 8203 6152
1250 10 254 8203
1500 10 254 10 254
1750 12 305 12 305
2000 12 305 12 305
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 combustion air system
MUST be supported by the building structure not the
boiler/water heater.