010-200002-000
Page 29
HB IOM 1.1 2-13-2014
SERVICE
General
1.
Place a suitable walkway to protect floor insula-
tion whenever entering the fan section.
2.
Review Safety Considerations at beginning of
these instructions. Good safety habits are im-
portant tools when performing service proce-
dures.
3.
To make speed measurements, use a strobe-
style tachometer or calculate per Step 6 of Start-
Up, Check List.
Fan Motor Replacement
1.
Shut off motor power.
2.
Disconnect and tag power wires at motor termi-
nals.
3.
Loosen motor brace-to-mounting-rail attaching
bolts. Loosen belt tensioning bolts to adjust the
motor position so V-belts can be removed without
stretching over grooves.
4.
Mark belt as to position. Remove and set aside
belts.
5.
Remove motor to motor bracket hold-down bolts.
6.
Remove motor pulley and set aside.
7.
Remove motor.
8.
Install new motor. Reassemble by reversing
Steps 1-6. Be sure to reinstall multiple belts in
their original position. Use a complete new set if
required. Do not stretch belts over sheaves. Re-
view the sections on motor and sheave installa-
tion, sheave alignment and belt tensioning dis-
cussed previously (Fig. 29-31).
9.
Reconnect motor leads and restore power.
Check fan for proper rotation as described in
Start-Up, Check List.
Coil Cleaning
DETERGENT — Spray mild detergent solution on
coils with garden-type sprayer. Rinse with fresh wa-
ter. Check to ensure condensate line is free. Excess
water from cleaning may flood unit if condensate line
is plugged.
Winter Shutdown (Chilled Water Coil Only)
ANTIFREEZE METHODS OF COIL PROTECTION
1.
Close coil water supply and return valves.
2.
Drain coil as follows:
Method I
— ‘Break’ flange of coupling at each
header location. Separate flange or coupling con-
nection to facilitate coil draining.
Method II
— Open both valves to auxiliary
drain piping.
3. After coil is drained:
Method I
— Connect line with a service valve and
union from upper connection to an antifreeze res-
ervoir. Connect a self-priming reversible pump
between the low header connection and the res-
ervoir.
Method II
— Make connection to auxiliary drain
valves.
4.
Fill reservoir with any inhibited antifreeze ac-
ceptable to code and underwriter authority.
5.
Open service valve and circulate solution for
15 minutes; then check its strength.
6.
If solution is too weak, add more antifreeze
until desired strength is reached, then circu-
late solution through coil for 15 minutes or
until concentration is satisfactory.
7.
Remove upper line from reservoir to reversi-
ble pump. Drain coil to reservoir and then
close service valve.
8.
Break union and remove reservoir and its
lines.
9.
Leave coil flanges or coupling open and aux-
iliary drain valves open until spring.
AIR DRYING METHOD OF COIL PROTECTION
(Unit and coil must be level for this method.)
1.
Close coil water supply and return main
valves.
2.
Drain coil as described in procedures for Anti-
freeze Methods of Coil Protection.
3.
Connect air supply or air blower to inlet head-
er connection and close its drain connection.
4.
Circulate air and check for air dryness by
holding mirror in front of open vent in outlet
header drain connection. Mirror will fog if wa-
ter is still present.
5.
Allow coil to stand for a few minutes; repeat
Step 4 until coil is dry.
PIPING — Chilled water and hot water coils
should always be piped for counterflow. (Fluid
should enter the coil at the leaving-air side.)
Steam coils must have the condensate connec-
tion at bottom of coil.
START-UP (cont’d)
b. Drive misalignment.
c. Mismatched, worn or loose belts.
d. Wheel or sheaves loose on shaft.
e. Loose bearings.
f. Loose mounting bolts.
g. Motor out of balance.
h. Sheaves eccentric or out of balance.
i. Vibration isolators improperly adjusted.
j. Out-of-balance or corroded wheel (rebalance or
replace if necessary).
k. Accumulation of material on wheel (remove ex-
cess material).
DANGER
NEVER enter an enclosed fan cabinet or reach
into a unit while the fan is running.
LOCK OPEN AND TAG the fan motor power dis-
connect switch before working on a fan. Take fus-
es with you and note removal on tag. Electric
shock can cause personal injury or death.
LOCK OPEN AND TAG the electric heat coil pow-
er disconnect switch before working on or near
heaters.
Failure to follow these warnings could lead to per-
sonal injury or death.
