SERVICING
77
FORMULAS:
Heating Output = KW x 3413 x Corr. Factor
Actual CFM = CFM (from table) x Corr. Factor
BTUH = KW x 3413
BTUH = CFM x 1.08 x Temperature Rise (T)
CFM = KW x 3413
1.08 x T
T = BTUH
CFM x 1.08
S-61A CHECKING HEATER LIMIT CONTROL(S)
Each individual heater element is protected with a limit control
device connected in series with each element to prevent
overheating of components in case of low airflow. This limit
control will open its circuit at approximately 150°F.
HIGH VOLTAGE!
Disconnect ALL power before servicing
or installing. Multiple power sources
may be present. Failure to do so may
cause property damage, personal injury
or death.
1. Remove the wiring from the control terminals.
2. Using an ohmmeter, test for continuity across the nor-
mally closed contacts. No reading indicates the control
is open - replace if necessary.
IF FOUND OPEN - REPLACE - DO NOT WIRE AROUND.
S-61B CHECKING HEATER FUSE LINK
(OPTIONAL ELECTRIC HEATERS)
Each individual heater element is protected with a one time
fuse link which is connected in series with the element. The
fuse link will open at approximately 333°.
WARNING
Disconnect ALL power before servicing.
1. Remove heater element assembly so as to expose fuse
link.
2. Using an ohmmeter, test across the fuse link for continu-
ity - no reading indicates the link is open. Replace as
necessary.
NOTE:
The link is designed to open at approximately 333°F.
DO NOT WIRE AROUND - determine reason for failure.
S-62 CHECKING HEATER ELEMENTS
WARNING
Disconnect ALL power before servicing.
1. Disassemble and remove the heating element.
2. Visually inspect the heater assembly for any breaks in the
wire or broken insulators.
3. Using an ohmmeter, test the element for continuity - no
reading indicates the element is open. Replace as
necessary.
S-100 REFRIGERATION REPAIR PRACTICE
DANGER
Always remove the refrigerant charge in a proper
manner before applying heat to the system.
When repairing the refrigeration system:
HIGH VOLTAGE!
Disconnect ALL power before servicing
or installing. Multiple power sources
may be present. Failure to do so may
cause property damage, personal injury
or death.
1. Never open a system that is under vacuum. Air and
moisture will be drawn in.
2. Plug or cap all openings.
3. Remove all burrs and clean the brazing surfaces of the
tubing with sand cloth or paper. Brazing materials do not
flow well on oxidized or oily surfaces.
4. Clean the inside of all new tubing to remove oils and pipe
chips.
5. When brazing, sweep the tubing with dry nitrogen to
prevent the formation of oxides on the inside surfaces.
6. Complete any repair by replacing the liquid line drier in the
system, evacuate and charge.
BRAZING MATERIALS
I
MPORTANT NOTE:
Torch heat required to braze tubes of
various sizes is proportional to the size of the tube. Tubes of
smaller size require less heat to bring the tube to brazing
temperature before adding brazing alloy. Applying too much
heat to any tube can melt the tube. Service personnel must
use the appropriate heat level for the size of the tube being
brazed.
