49
OPERATION
Lighting Instructions
1. Before operation, make sure you have read all of
the safety information in this manual.
2. Remove upper front panel.
3. Set the thermostat to the lowest setting.
4. Turn off all electrical power to the appliance.
5. This appliance is equipped with an ignition device
which automatically lights the burner. Do not try to
light the burner by hand.
6. Turn on main manual gas valve field installed near
gas inlet connection on back of heater.
7. Wait 5 minutes to clear out any gas. Then smell for
gas, especially near the floor. If you then smell
gas, STOP! Follow the steps in the safety informa-
tion on the front cover of this manual. If you do not
smell gas, go to next step.
8. Turn on all electrical power to the appliance.
9. Set thermostat to desired setting. The appliance
will operate. The igniter will glow after the pre-
purge time delay (15 seconds). After igniter
reaches temperature (30 seconds) the main valve
should open. System will try for ignition up to three
times (one time on optional single-try ignition mod-
ule). If flame is not sensed, lockout will
commence.
10. If the appliance will not operate, follow the instruc-
tions “To Turn Off Gas To Appliance,” and call your
service technician or gas supplier.
11. Replace upper front panel.
12. If heater fails to start, verify the following:
a. There are no loose connections or that the
service switch is off.
b. High temperature limit switch (optional) is set
above water temperature or manual reset high
limit is not tripped.
c. Enable/Disable circuit is closed.
d. Gas is on at the meter and the heater.
e. Incoming dynamic gas pressure to the gas
valve is NOT less than 4.0 in. WC for natural
gas or propane gas.
To Turn Off Gas To Appliance
1. Shut off manual gas valve field installed near gas
inlet connection on back of heater.
2. Remove upper front panel.
3. Adjust setpoint to lowest setting.
4. Turn off all electrical power to the appliance if serv-
ice is to be performed.
5. Replace access panel.
TROUBLESHOOTING
MVB Error Codes
If any of the sensors detect an abnormal condition or
an internal component fails during the operation of the
MVB, the display may show the error. This code may
either be the result of a temporary condition in which
case the display will revert to its normal readout when
the condition is corrected, or it may be the result of a
condition that the controller has evaluated as not safe
to restart the unit. In this case, the unit control will be
locked out, requiring the maintenance person to man-
ually reset the control by pressing and releasing the
RESET
key.
Heater Errors
When an error condition occurs, the controller will dis-
play an error code on the display module. These error
codes and several suggested corrective actions are
included in the MVB Fault Text section on the following
page.
Heater Faults
1. When a fault condition occurs, the controller will
flash a red light on the PIM™ and display the error
code on the user interface. The alarm output will
also be activated. Most fault conditions will also
cause the boiler pump to run in an attempt to cool
the unit.
Summary of Contents for 503A
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