Aerco Benchmark BMK 750 User Manual page 63

Benchmark 750-3000 Boiler Operation, Service, Maintenance Guide - KOREA
SECTION 5 – TROUBLESHOOTING GUIDE
TABLE 5-1: Boiler Troubleshooting Procedures
Fault
Probable Causes
Indication
Faulty Water temperature switch.
1.
2. Incorrect PID settings.
Faulty shell temperature sensor.
3.
HIGH WATER
TEMP
SWITCH OPEN
Unit in MANUAL mode.
4.
Unit setpoint is greater than Over Temperature
5.
switch setpoint.
System flow rate changes are occurring faster
6.
than units can respond.
See HIGH WATER TEMPERATURE SWITCH
1.
HIGH WATER
OPEN.
TEMPERATURE
Temp HI Limit setting is too low.
2.
1. Communication fault has occurred between the
IGN BOARD
PMC board and Ignition/Stepper (IGST) board.
COMM FAULT
OMM-0128_0C
GF-206-K
Corrective Action
Test the temperature switch to insure it trips at its actual water
1.
temperature setting.
2. Check PID settings (see Section 2-7: Tuning Menu, items 1 -3, for
details). If the settings have been changed, record the current
readings then reset them to the default values.
Using the resistance charts in Appendix C, measure the resistance
3.
of Shell sensor and BTU sensor at a known water temperature.
If unit is in MANUAL mode, switch to AUTO mode.
4.
Check setpoint of unit and setpoint of Temperature switch; Ensure
5.
that the temperature switch is set higher than the unit's setpoint.
If the system is a variable flow system, monitor system flow
6.
changes to ensure that the rate of flow change is not faster than
what the units can respond to.
See HIGH WATER TEMPERATURE SWITCH OPEN.
1.
Check Temp HI Limit setting.
2.
Press CLEAR button and restart unit. If fault persists, contact
1.
qualified Service Personnel.
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
Ph.: 800-526-0288
Page 63 of 146
11/29/2017