Service manual

A DJM3.2 MANUAL
Blower/Damper Operation
The combination of energized night (K) and fan (FS) terminals set the blower and damper operation at
night.
DAY (FS on) Continuous Blower, Dampers Open, Discharge Control
NIGHT (FS off, K on) Intermittent Blower, Dampers Off, Room Control
ALTERNATE NIGHT OPERATION Continuous Blower, Dampers Off, Discharge Control
(HS, FS, K terminals all energized) with Room Reset
XXII. BURNER SET UP
Manual Service Switch
The service switch allows complete manual control over the burner-firing rate. When the service
switch is in the on position, and if the fan switch is on, the burner will cycle on. The burner will be held
on and will not cycle off. Rotating Pot Hi Service will adjust the firing rate from minimum to maximum.
The calculated set-point resistor readout does not function in this mode.
NOTE: If the service switch is on, the DJM3.2 will not lock out on flame failure. This was
done to prevent the whole unit from locking out on flame failure resulting in faster
burner servicing. The low limit is still active in the service mode.
Manual Firing Set Up Pot
This pot is designed to allow a service technician to manually set the burner to any firing rate he
chooses. If the service switch (dipswitch 5) is on and the blower switch (terminal FS) is powered, the
burner firing rate is controlled by the service pot (Pot Hi Service). Pot Hi Service is located close to the
+ terminal and the dipswitches. Rotating this pot will allow the firing rate to be set at any rate between
low and high fire.
NOTE: S/A fan (terminal FS) may need to be turned on manually when service switch is
on.
Important Usage Notes Regarding the Service Pot
• The unit must not be left in the service mode. When leaving the unit make sure that dipswitch
5 is OFF.
• When the service switch is on the burner will not cycle off. (The S/A fan may need to be turned on
manually when service switch is on.)
• Low fire is at approximately pot position 6 o’clock and high fire is at pot position 3 o’clock.
• The low limit is still functional and may lock out if the firing rate has been manually set too low.
• An irregular flashing of LED 3 indicates that the unit is in service mode. (Dipswitch 5 is still ON.)
Burner Selection
The DJM3.2 is designed to operate with both the standard (round burner plate) and high turndown
(rectangular) burners. The selection is made by cutting a jumper wire # R100 which is located on the
small board. (The DJM3.2 must be turned over to access the jumper wire.)
NOTE: Jumper wire R100 is cut only for the high turndown burner operation. Caution –
do not cut resistor R100 on the large board.
The small board contains two pots located next to the terminal strip. These pots are accessed from
the front of the control and are designed to be adjusted by a qualified service technician only.
DO NOT ADJUST ANY OTHER POTS LOCATED ON THE SMALL BOARD, WHICH ARE NOT
ACCESSIBLE FROM THE FRONT OF THE DJM3.2.
Page 28 Revised: 3/11/99