Mammoth 800 to 5500 CFM: Dedicated Outdoor Air System with Enthalpy Wheels (VHC) - Manual (Page 18)

MAMM-VHC-IOM-1A (JANUARY 2013) 18
Both motor shaft and fan bore must be completely free of
paint, grease, oil and dirt. If necessary, clean the surfaces
with non-petroleum based solvent, such as isopropyl alco-
hol. Insert the bushing into the fan, making sure the mating
hub is flush against the shoulder at the flats. Position the
assembly at the desired location on the motor shaft and
hand tighten nut (clockwise) until the assembly becomes
snug on the shaft.
Using a torque wrench and a 1¾” socket, tighten the nut to
the proper installation torque. See Table 3 for torque value.
Fan should overlap inlet cone by 3/8” [9 mm] and have a
clearance of 1/16” [2 mm]. Motor/fan assembly position is
adjustable by loosening the four bolts (#3, Figure 7) and
sliding shelf forwards and back.
Plenum Fan and Motor Service
Figure 7: Plenum fan and motor
WARNING
Disconnect the main power switch to the unit before per-
forming service and maintenance procedures.
!
WARNING
Do not hammer or use any type of impact to force the
bushing along the shaft.
!
WARNING
The shaft must fully engage the shaft gripping area of the
bushing.
!
Table 3: Torque Value
Shaft Size ft-lb
5/8” to 3/4” 100
13/16” to 1” 125
1-1/16” to 1¼” 167
After disconnecting the power from the unit, open the ser-
vice door for the cassette access. Disconnect the service
connector between the motor and the control box. Remove
the exhaust filters and slide the cassette out of the unit.
Take care to not damage the rotor face or any of the cas-
sette seals. Proper support must be provided so the cas-
sette is not dropped.
Cassette Removal