Burnham MST396 - Manual (Page 42)

4
WARNING
Before installation of the boiler is considered
complete, the operation of all boiler controls must
be checked, particularly the primary control and
pressure limit control.
2. VERIFY PRIMARY CONTROL FEATURES
using procedures outlined in Instructions furnished
with control or instructions as follows:
a. FEATURES AND CONTROLS
i. The R7184 is a microprocessor-based
control. The indicator light provides
diagnostic information for lockout, recycling
and patented cad cell status. There is a
manual reset button to exit the Lockout
Mode and enter the Idle Mode (see Figure
25).
Figure 5: R184 Terminals, LED and Reset Button
ii. Pump Priming Cycle: To facilitate purging
air from the oil lines and filters, the R7184
can be placed in a purge routine by pressing
and releasing the reset button during the
safety check, delayed valve-on, ignition or
carry-over periods.
iii. Limited Recycle: This feature limits the
number of recycle trials (for each call
for heat) to a maximum of three trials. If
the flame is lost three times and does not
successfully satisfy a call for heat, the
R7184 locks out.
iv. Limited Reset (Restricted Mode): In order
to limit the accumulation of unburned oil in
the combustion area, the control can only be
reset three times. The reset count returns to
zero each time a call for heat is successfully
completed.
• To reset from Restricted Mode: Press and
hold the reset button for 30 seconds.
When the LED flashes twice, the device
has reset.
v. T-T Jumper: Select models have pre-
installed T-T jumper. Do not remove
jumper. See Figure 25.
vi. Diagnostic LED: The indicator light on oil
primary control provides lockout, recycle
and cad cell indications as follows:
• Flashing at 1 Hz (½ second on, ½ second
off): system is locked out or in Restricted
Mode.
• Flashing at ¼ Hz (2 seconds on, 2 seconds
off): control is in Recycle Mode.
• On: cad cell is sensing flame.
•
Off: cad cell is not sensing flame.
vii. Cad Cell Resistance Check: For proper
operation it is important that the cad cell
resistance is below 1600 ohms. During a
normal call for heat, once the control has
entered the Run Mode, press and release the
reset button. Indicator light will flash 1 to 4
flashes. See Table 7 for equivalent cad cell
resistance.
TABLE : CAD CELL RESISTANCE WHEN
SENSING FLAME
b. CHECK OIL PRIMARY CONTROL
CAUTION
Due to the potential hazard of line voltage,
only a trained, experienced service technician
should perform the following safety checks.
This control contains no field-serviceable
parts. Do not attempt to take it apart.
Replace entire control if operation is not as
described.
i. Preliminary Steps
• Check wiring connections and power
supply.
• Make sure power is on to the controls.
• Make sure limit control is closed.
•
Check contacts between ignitor and the
electrodes.
• Check the oil pump pressure.
• Check the piping to the oil tank.
• Check the oil nozzle, oil supply and oil
filter.
ii. Check Safety Features
Safe Start:
Flashes Cad Cell Resistance in ohms
1 Less than 400
2 More than 400 and less than 800
3 More than 800 and less than 1600
4 More than 1600 and less than 5000