McQuay IM 777-7
15
Mechanical Installation
Internal Isolation Assembly
Adjustment
On units with internally isolated fan and motor assemblies, the
assemblies are secured for shipment. with a tie-down at each
point of isolation.
Before Operating the Unit:
Remove the shipping brackets and tie-down bolts (see
Figure 25
,
Figure 26
and
Figure 27
) and discard. The shipping
brackets located on the opposite drive side of the unit are
difficult to access from the drive side of the unit. Either
remove them before the unit is assembled or remove the panel
on the opposite drive side to gain access.
The spring isolators under the four corners of the fan and
motor assembly are factory adjusted while the fan was not
running. See
Table 1
through
Table 5
below. With the unit
operating at normal cfm and static pressure, all the isolators
should be at the same height opening. If adjustments are
required, loosen the 1/2" cap screw on top of the isolator and
turn the adjusting bolt to lower or raise the fan and motor base.
Retighten the cap screw when adjustments are completed.
For models 040 through 090 with housed fans, the isolators
should be at equal height during fan operation (6"). Center the
fan outlet in the outlet panel opening. If adjustment is required,
loosen the cap screw on top of the isolator assembly. Turn the
adjustment nut below the fan frame to lower or raise the fan
motor and frame assembly. Retighten the cap screw on top of
the isolator assembly.
Figure 24: Adjusting Large Spring Mount Assembly
Table 1: Motor Beside Fan Spring Mount Adjustments
Spring mount adjustment at rest
Isolator
position
Top or bottom
horz. H
Downblast
H
Upblast
H
Unit sizes 003 – 035
1
3.75
3.75
4.25
2
4.25
3.75
4.25
3
4.25
3.75
4.25
4
3.75
3.75
4.25
Unit sizes 040 – 090
1
6.00
6.75
6.75
2
6.50
6.75
6.75
3
6.50
6.75
6.75
4
6.00
6.75
6.75
Table 2: Motor Behind Fan Spring Mount Adjustments
Spring mount adjustment at rest
Isolator
position
Top or bottom
horz. H
Downblast
H
Upblast
H
Unit sizes 003 – 035
1
6.75
6.75
6.75
2
6.75
6.75
6.75
3
6.75
6.75
6.75
4
6.75
6.75
6.75
Unit sizes 040 – 090
1
6.75
6.75
6.75
2
6.75
6.75
6.75
3
6.75
6.75
6.75
4
6.75
6.75
6.75
Table 3: Class II Belt-Drive Plenum Fan Spring Height
Fan Size
Isolator Type
Operating Height (in.)
13–16
Standard 2" Deflection
4.5
18–36
Standard 2" Deflection
4.0
13–36
Seismic
4.0
40–60
All
6.75
Table 4: Class III Plenum Fan Spring Height
Cabinet Width
Isolator Type
Operating Height (in.)
Width < 108"
All
4.0
Width > or = 108"
All
6.75
Table 5: Class II Direct-Drive Plenum Fan Spring Height
Fan Size
Isolator Type
Operating Height (in.)
11–36
All
4.0
40–44
All
6.75
Adjusting bolt
6"
