175245-YIM-C-1008
30
Johnson Controls Unitary Products
If the temperature limit opens three times within one
hour, it will lock-on the indoor blower motor and a flash
code is initiated (See Table 20).
SAFETY CONTROLS
The unit control board monitors the temperature limit
switch of electric heat units.
The control circuit includes the following safety con-
trols:
1. Temperature Limit Switch (TLS 1, 2).
This control is located inside the heater compart-
ment and is set to open at the temperature indi-
cated in the Limit Control Setting Table 18. It resets
automatically. The limit switch operates when a
high temperature condition, caused by inadequate
supply air flow occurs, thus shutting down the
heater and energizing the blower.
2. Temperature Limit Switch (TLS 3, 4, 5 and 6).
This control is located inside the heater compart-
ment and is set to open at the temperature indi-
cated in the Limit Control Setting Table 18. It is a
manual reset limit. These limit switches will de-
energize the heaters should the primary limit fail to
open or the contactors fail to open in a failure
mode.
FLASH CODES
The UCB will initiate a flash code associated with
errors within the system. Refer to UNIT CONTROL
BOARD FLASH CODES Table 20.
RESET
Remove the call for heating by lowering the thermostat
setting lower than the conditioned space temperature.
This resets any flash codes.
HEAT ANTICIPATOR SETPOINTS
It is important that the anticipator setpoint be correct.
Too high of a setting will result in longer heat cycles
and a greater temperature swing in the conditioned
space. Reducing the value below the correct setpoint
will give shorter "ON" cycles and may result in the low-
ering of the temperature within the conditioned space.
Refer to Table 19 for the required heat anticipator set-
ting.
START-UP (COOLING)
PRESTART CHECK LIST
After installation has been completed:
1. Check the electrical supply voltage being supplied.
Be sure that it is the same as listed on the unit
nameplate.
2. Set the room thermostat to the off position.
TABLE 18: LIMIT CONTROL SETTING
UNIT
(Tons)
VOLTAGE
HEATER
kW
TEMPERATURE LIMIT
SWITCH 1, 2
OPENS, °F
TEMPERATURE
LIMIT SWITCH 3, 4, 5,
6 OPENS, °F
20
240
18
140
200
36
140
200
54
140
200
72
140
200
460
18
120
170
36
120
170
54
120
170
72
120
170
600
18
120
-
36
120
-
54
120
-
72
120
-
TABLE 19: ELECTRIC HEAT ANTICIPATOR
SETPOINTS
HEATER
KW
VOLTAGE
SETTING, AMPS
TH2
18
208/230-3-60
0.29
36
0.29
54
0.58
72
0.58
18
460-3-60
0.29
36
0.29
54
0.29
72
0.29
18
575-3-60
0.29
36
0.29
54
0.29
72
0.29
