Cycling Issues - IBC CX Series Installation And Operating Manual

8.3.4 Cycling issues

Issue Diagnosis
Rapid Improper values
Cycling entered via keypad.
Excess condensate in
venting.
Obstruction in
condensate trap.
Improper vent length or
improper slope to vent.
Incorrect settings or
defective thermostat.
Air in system or
marginal water flow.
Slow combustion air
blower.
Dirty burner/heat
exchanger.
Low water flow due to
improper piping.
Low water flow due to
undersized pump.
Low water flow due to
restrictions in water
pipe.
Low radiation.
Appliance over-fired.
Appliance Oversized.
Improperly set or
defective controls.
Cycling issues
Check load maximum temps are above target temps, by ½
of the selected boiler differential. Ensure boiler differential
is OK (16 - 30 °F is generally adequate)
Check venting slopes on horizontal runs. Look for sags.
Inspect and clean condensate trap.
Check venting. Compare vent length and diameter.
Check operation. Refer to manufacturer's instructions.
Check setting with ammeter.
Bleed/purge system as required. Confirm adequate pump
size and temp rise in the heat exchanger.
Check that CO level is within specification.
2
Check pressure drop.
Refer to recommended piping for the respective boiler
model.
Check manufacturer's rating charts/check temperature
differential across heat exchanger.
Check temperature differential across zone/heat
exchanger.
Check actual amount of radiation per zone and refer to
manufacturer's rating tables.
Clock gas meter/check gas pressure with manometer/
check CO level.
2
Check load calculation vs. minimum boiler output.
Check operation with ohmmeter/voltmeter.
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8.3.4 Cycling issues
Fix