28
McQuay IM 777-2
Service and Maintenance
Maintaining the Coil
1
The coil must be clean to obtain maximum performance.
Check once a year under normal operating conditions and,
if dirty, brush or vacuum clean. Use a chemical coil cleaner
on multiple row coils. Read and follow the chemical
cleaner’s instructions as some cleaners may contain harsh
chemicals. Take care not to damage fins while cleaning.
2
Drain pans in any air conditioning unit may have some
moisture. Algae, etc., can grow due to airborne spores and
bacteria. Periodic cleaning is necessary to prevent this
buildup from plugging the drain and causing the drain pan
to overflow. Also, keep the drain pans clean to prevent the
spread of disease. Cleaning should be performed by
qualified personnel.
3
Dirt and lint can clog the condensate drain, especially with
dirty filters. Inspect twice a year to help avoid overflow.
Winterizing Water Coils
Coils can freeze due to air stratification or failure of outdoor
air dampers and/or preheat controls. Do not depend on routine
draining of water cooling coils for winter shutdown as
insurance against freeze-up. Severe coil damage can result.
Drain all coils as thoroughly as possible and then treat in the
following manner.
•
Fill each coil independently with an antifreeze solution
using a small circulating pump and again thoroughly drain.
•
Check freezing point of antifreeze before proceeding to next
coil. Due to a small amount of water always remaining in
each coil, there is a diluting effect. The small amount of
antifreeze solution remaining in the coil must always be
concentrated enough to prevent freeze-up.
Note –
Carefully read instructions for mixing antifreeze solution
used. Some products have a higher freezing point in their
natural state when mixed with water.
McQuay
International is not responsible for the freezing of
coils.
Removing and Replacing Components
See “Access Doors and Panels” on page 7 for instructions on
removing panels and opening fan access doors to remove or
replace components.
Removing the Fan Section
The fan shaft, motor, and any drive components can be
removed and replaced through the access door opening. If
required, the side panel can be removed for additional access.
If fan replacement is required, the entire fan assembly can be
pulled out the side of the cabinet. The fan assembly includes
the fan housing, the bearing support, and the fan base.
Table 16: Filter Pressure Drops
Bag filters—DriPak 2000
Efficiency
45%
65%
85%
95%
Rated velocity (fpm)
625
500
500
500
Initial pressure drop
.20–.26 .21–30 .34–.48
.50–.70
Initial pressure drop
1.0
1.0
1.0
1.0
Cartridge filters—Varicel II MH, 4.25" deep
Efficiency
65%
85%
95%
Efficiency
Rated velocity (fpm)
500
500
500
Rated velocity (fpm)
Initial pressure drop
.43
.61
.70
Initial pressure drop
Final pressure drop
1.5
1.5
1.5
Final pressure drop
Cartridge filters—Varicel SH, 12" deep
Efficiency
70%
Rated velocity (fpm)
500
Initial pressure drop
.39
Final pressure drop
1.2
Pleated panel filters
Type
Perfect pleat
AMAir 300 4"
Efficiency
30%
30%
Rated Velocity (fpm)
500
625
Initial Pressure Drop
.36
.36
Final Pressure Drop
1.0
1.0
5700 filters
Efficiency
N/A
Rated velocity (fpm)
500
Initial pressure drop
.25
Final pressure drop
1.0
Pleated 62 Plus filters
Size
2"
4"
Efficiency
70%
70%
Initial pressure drop
.42
.37
Final pressure drop
1.0
1.0
WARNING
Mold can cause personal injury.
Clean drain pan regularly
so mold does not develop.
AVERTISSEMENT
La moisissure présente un danger respiratoire.
Pour éviter
la moisissure, nettoyer régulièrement le bassin de drainage.
WARNING
Before removing any component, lock out and tag out all
power to the unit.
Fans and belts can cause severe personal
injury or death.
AVERTISSEMENT
Avant d’enlever toute composante, couper et indiquer que
l’alimentation électrique à l’unité est coupée.
Les
ventilateurs et les courroies peuvent entraîner des blessures
personelles graves ou même la mort.
