Heating Operation Errors; Temperature Limit; Safety Controls; Flash Codes - York SUNLINE MagnaDRY WR300 Installation Manual

If the second stage of heat is required, heater
contactor (7M) will be energized. Note that on
the 54 KW, 240V heater, heater contactors
(7M & 8M) will be energized and on the 72 KW,
240V heater, heater contactors (8M & 9M) will
be energized. After completing the specified
fan on delay for heating, the UCB will energize
the blower motor.
b. The thermostat will cycle the electric heat to satisfy
the heating requirements of the conditioned space.
NOTE: All 240 & 480V heaters are provided with man-
ual reset backup protection limits. These will
de-energize the heaters should the primary
limit fail to open or the contactors fail to open in
a failure mode.

HEATING OPERATION ERRORS

TEMPERATURE LIMIT

If the UCB senses zero volts from the high temperature
limit, the indoor blower motor is immediately energized.
This limit is monitored regardless of unit operation sta-
tus, i.e. the limit is monitored at all times.
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 36).

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 31. 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-
Johnson Controls Unitary Products
cated in the Limit Control Setting Table 31. 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.
TABLE 31: LIMIT CONTROL SETTING
UNIT HEATER
VOLTAGE
(Tons) kW
18
36
15 240
54
72
18
36
20, 25 240
54
72
18
36
15, 20,
460
25
54
72
18
36
15, 20,
600
25
54
72

FLASH CODES

The UCB will initiate a flash code associated with
errors within the system. Refer to UNIT CONTROL
BOARD FLASH CODES Table 36.

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 32 for the required heat anticipator set-
ting.
284813-YIM-C-1008
TEMPERATURE TEMPERATURE
LIMIT SWITCH 1, 2 LIMIT SWITCH 3,
OPENS, ºF 4, 5, 6 OPENS, ºF
120 170
120 170
120 170
120 170
140 200
140 200
140 200
140 200
120 170
120 170
120 170
120 170
120 -
120 -
120 -
120 -
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