Service manual

MSE Series Electric Boilers – Installation and Service Manual
16
Troubleshooting Guide Section 7
7.1 TROUBLESHOOTING – For Use of Licensed Electricians Only
WARNING
RISK OF ELECTROCUTION – HIGH VOLTAGE - ALWAYS SHUT OFF MAIN POWER TO THE
ELEMENT HEATING CIRCUIT BEFORE TROUBLESHOOTING! Also, beware of 120V power while
troubleshooting near the line-in terminals (L1&L2), pump terminals (P1&P2), transformer and
pump fuse.
This section is meant to assist the service technician when troubleshooting the electric boiler. As in any
troubleshooting procedure, it is important to isolate a problem as much as possible before proceeding.
Carefully check all external and internal wiring following the wiring diagram sticker on the back of the
boiler's door. An additional wiring diagram is enclosed with this manual. Often the controller error
message (refer to the BC-1 Boiler Controller Manual) can be a great help in identifying the cause of a
problem.
PROBLEM CAUSE SOLUTION / CHECK
• Incorrect supply power. • Check for 115V (AC) across L1 and
L2.
• Faulty transformer. • Check for 24V (AC) across terminals
C-1 and HL-16.
• Faulty high limit switch. • Check for open circuit between HL-15
and HL-16 and 24V (AC) across HL-16
and C-1.
BC-1 display is blank.
• Internal control fault. • Replace controller.
• E01 – Controller unable to read from
its EEPROM
• Verify all the settings in the adjust
menu are correct.
• Shr – Controller is unable to read from
one of the sensors.
• Check for short circuit at the sensor
which is displayed on the LCD.
• 0Pn – Controller is unable to read from
one of the sensors.
• Check for loose connection/open
circuit at the sensor which is displayed
on the LCD.
BC-1 displays an error message.
• Defective sensor or controller. • Perform "Sensor Check" described in
Section 7.2 and replace if necessary.
• Thermostat fault. • Disconnect thermostat from controller,
turn thermostat to maximum setting,
and check continuity.
No heat when called by thermostat and
stages are NOT displayed on LCD
screen.
• Internal control fault. • With thermostat disconnected from
terminal block, voltmeter should read
24V (AC) across terminals HT and R.
• Main fuses blown (if applicable). • Check main fuses and replace if
blown.
• Internal control fault. • Display stage indicator by adjusting
thermostat to maximum setting and
check for 24V (AC) across stages 1, 2,
and 3.
No heat when called by thermostat and
stage indicators are displayed on LCD
screen.
• Main contactor(s) fault. • Check each contactor coil's terminals
for a supplied voltage of 24V (AC). If
present, main contactor(s) are faulty
and must be replaced. If not present,
wiring continuity fault exists – check
and repair.