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.
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
with the Standard for Parking Structures, ANSI/NFPA 88A, or the Standard for Repair Garages,
ANSI/NFPA 88B, and with CAN/CGA B149 Installation Codes.
Roof Mount Installation
Installation with Exhaust Fan
Summary of Contents for Modular Direct Fired Heaters
Page 2: ......
