Thomas & Betts UDAP - Manual (Page 19)

Form RZ-NA I-UDA, Mfg #195673 Rev 5, Page 19
This heater is equipped with a direct spark integrated control module (circuit board).
The module monitors the safety devices and controls the operation of the fan and
venter motors and the gas valve between heat cycles. 20. Ignition
System
Control Status - Green LED Codes
Steady ON ....... Normal Operation, No call for heat
Fast Flash ........ Normal Operation, Call for heat
1 Flash ............ System Lockout, Failed to detect or sustain
flame
2 Flashes ......... Pressure Switch Did Not Close within 30
Seconds of Venter Motor
3 Flashes ......... High Limit or Flame Rollout Switch Open
4 Flashes ......... Pressure switch is closed before venter
motor is energized
Steady OFF ..... Blown Fuse, No Power, or Defective Board
FIGURE 14 – DSI Integrated Control Module (circuit board)
Spark
Transformer
Contr
ol
Plug
Fuse
Thermostat
Connections
Fan/Blower
Off
Delay
Status
Lights
x
Flame Status - Yellow LED Codes
Steady ON....... Flame is sensed
Slow Flash ...... Weak flame (current below 1.0
microamps ±50%)
Fast Flash ........ Undesired Flame (valve open
and no call for heat)
Fan/Blower OFF Delay Settings (dip switches)
SW-1
SW-2 Time
Off Off 120 seconds (factory setting)
Off On 90 seconds
On Off 160 seconds
On On 180 seconds
LED Lights
Dip Switch
Normal Heat Cycle
Operating
Sequence 1) Call for Heat - The thermostat calls for heat by energizing the “W” terminal.
The control checks to see that the limit switch is closed and the pressure switch is
open. If the limit switch is open, the control responds as defined in the “Abnormal
Heat Cycle, Limit Switch Operation”. If the pressure switch is closed, the control
will do four flashes on the green LED and wait indefinitely for the pressure switch
to open. If the pressure switch is open, the control proceeds to prepurge.
2) Prepurge - The control energizes the venter motor and waits for the pressure
switch to close. If the pressure switch does not close within 30 seconds of the
venter motor energizing, the control will do two flashes on the green LED. The
control will leave the venter motor energized indefinitely as long as the call for
heat remains and the pressure switch is open.
19. Door Switch
- Model
UDAS only
All sizes of Model UDAS heaters are equipped with a door switch which prevents
the heater from operating when the service door panel is open. The service panel
of a Model UDAS is equipped with a pliable gasket material that fully seals the
door to provide added protection from building air entering the combustion zone
of the heater. (For switch location, see FIGURE 18, page 31.)