IBC VFC 15-150 Installation And Operating Instructions Manual page 61

5.3.4 Temperature Problems
SYMPTOM
INSUFFICIENT HEAT
TEMPERATURE EXCEEDS
THERMOSTAT SETTING
ONE OR MORE ZONES DO
NOT HEAT PROPERLY
TROUBLESHOOTING
VFC 15-150, VFC 45-225 MODULATING GAS BOILERS
DIAGNOSIS
Operating
temperature too low.
Priority parameters
or load configuration
improperly set up.
Unit undersized.
Air trapped within
system.
Improper system
piping.
System pump
undersized.
Poor gas/air mixing.
Defective thermostat.
Obstruction in
condensate drain.
Unit cycling on
operating/ safety
controls.
System radiation
undersized.
Incorrect anticipator
setting.
Thermostat not level.
Air trapped within
zone(s) piping
Insufficient radiation/
excessive heat loss.
Insufficient flow rate
to zone(s).
Defective zone valve/
zone circulator.
REMEDY
Increase temperature target.
Review load configuration parameters.
Refer to Load Calculation vs. Boiler Output.
Bleed system as required.
Refer to recommended piping in Section 1.6
Check pump manufacturer's data/check temp
differential across heat exchanger.
Check CO2 level.
Refer to manufacturer's instructions.
Inspect and clean condensate drain.
Check operation with Ohmmeter/Voltmeter.
Check manufacturer's rating tables for capacity
per foot.
Check with Ammeter.
Check level.
Vent system/zone as required.
Check actual length of pipe using radiation / heat
loss calculation.
Check temperature drop across zone.
Check operation per manufacturer's instructions.
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