McQuay IM 777-4
29
Service and Maintenance
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‚ 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.
Removing the Fan Assembly
1
Remove the side panels and any intermediate supports
(follow instructions for side panel removal).
2
Once the panels and any intermediate supports are
removed, disconnect the neoprene bulk head seal that is
attached to the fan discharge.
3
Remove the four discharge angles that hold the neoprene
canvas in place around the discharge opening.
4
Disconnect the fan sled from each of the corner mounts
and pull the entire assembly out the side of the unit.
5
After the fan sled is out, loosen the fan bearings and pull
out the shaft.
6
Disconnect the fan housing from the fan sled, and
bearing support by removing the attaching bolts.
7
Replace the new fan, reconnect the shaft and bearings
and put the fan assembly in the cabinet.
8
Replace panels and fasteners.
Removing and Replacing the Coil
Removing Single Coils
Note:
Single coils are bolted to the unit on the connection end.
The connection end is held in place with a clamp.
1
Disconnect all piping and remove the brass plugs for the
vents and drains located in the connections.
2
Remove all screws and remove the access panel.
3
Remove the screws holding the coil in place.
4
Lift and pull the coil out the side.
Installing Single Coils
1
Slide the coil through the opening in the coil section onto
the bottom coil rests.
2
To prevent any air bypass around the coil, place coils up
against the coil bulkheads. See
Single Coil Top
Installation/Removal‚ page 30
.
3
Once the coil is in place, fasten the coil to the section.
4
Caulk the seams between the coil casings and bulkheads
.
5
If this is an additional coil being installed and not a
replacement, locate the coil supply and return
connections dimensionally. Carefully drill holes in the
end panels of the unit.
6
Remove the brass plugs for the vents and drains on the
connections.
7
Slip the panel over the connections.
8
Replace the brass plugs and panel fasteners.
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.
