FloAire F-D Installation - Manual (Page 6)

6
Recommended Supply Ductwork Sizes
Blower Size Duct Size Straight Duct Length
10 14 x 14 48 in.
12 16 x 16 54 in.
15 20 x 20 72 in.
18 24 x 24 86 in.
20 26 x 26 108 in.
25 32 x 32 168 in.
Assembly
Intakes and curbs are shipped unassembled. Upon unit arrival, follow the following procedure to
assemble the intake to the heater:
1. Apply silicone or weather-proof gasket on the back
side of the flanges of the intake hood or v-bank
intake.
2. Screw the flanges of the intake hood or v-bank to
the unit with the supplied sheet metal screws.
Place caulk on the outside of the screws to prevent
water leaks. If the unit is a modular unit with a v-
bank or evaporative cooler section, the v-bank or
evaporative cooler will bolt to the heater with the bolts provided.
Curb and Ductwork
This fan was specified for a specific CFM and static pressure. The ductwork attached to this unit will
significantly affect the airflow performance. Flexible ductwork and square elbows should not be used.
Also, transitions and turns in ductwork near the fan outlet will cause system effect and will drastically
increase the static pressure and reduce airflow. The chart below shows the minimum fan outlet duct
sizes and straight lengths recommended for optimal fan performance. Follow SMACNA guides and
recommendations for the remaining duct run. Fans designed for rooftop installation should be
installed on a prefabricated or factory built roof curb.
Follow curb manufacturer’s instructions for proper
curb installation. The unit should be installed on a
curb and/or rail elevated not less than 20” above
any surface. Be sure duct connection and fan outlet
are properly aligned and sealed. Secure fan to curb
through vertical portion of the ventilator base
assembly flange using a minimum of eight (8) lug
screws, anchor bolts, or other suitable fasteners (not
furnished). Shims may be required depending upon
curb installation and roofing material. Check all
fasteners for tightness. The diagrams below show
different mechanical installation configurations.
Adequate building relief shall be provided so as to not
over pressurize the building when the heating system
is operating at its rated capacity. This can be
accomplished by taking into account, through standard
engineering
methods, the structure’s designed
infiltration rate; by providing properly sized relief
openings; or by interlocking a powered exhaust
system; or by a combination of these methods.
Heaters installed with intake ductwork must be purged to replace at least four air changes of the volume
of the intake duct.
If the failure or malfunction of this heater creates a hazard to other fuel burning equipment in the building
(e.g. when the heater is providing make up air to a boiler room), the unit is to be interlocked to open inlet
air dampers or other such devices.
Units being installed in airplane hangars should be installed in accordance with the Standard for Aircraft
Hangars, ANSI/NFPA 409. Units being installed in public garages should be installed in accordance
Mixing Box Size Duct Size
1 19 x 15
2 25 x 24
3 31 x 29
4 37 x 34
5 44 x 44
Recommended Return Ductwork Sizes