Miscellaneous issues
Issue Diagnosis Fix
Boiler pump runs but load pumps do
not.
Wiring not
complete.
Supply power to the PV/L and PV/N
terminals from the incoming power
supply to the boiler. (Factory wired on
boilers with a factory installed
touchscreen controller)
Boiler stuck on initialize Fan board
failure
Replace the fan.
Boiler pump runs during parallel-
piped DHWcall
Boiler pump is
set to On.
Re-define the DHWload as DHWLoop
2 (5 button controls)to turn off the boiler
pump during domestic hot water calls.
On touch screen controllers, set the
boiler pump to Off in the Installer Setup
menu.
8.3.4 Cycling issues
Cycling issues
Issue Diagnosis Fix
Rapid
Cycling
Improper values
entered via keypad.
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)
Excess condensate
in venting.
Check venting slopes on horizontal runs. Look for sags.
Obstruction in
condensate trap.
Inspect and clean condensate trap.
Improper vent
length or improper
slope to vent.
Check venting. Compare vent length and diameter.
Incorrect settings or
defective
thermostat.
Check operation. Refer to manufacturer’s instructions. Check
setting with ammeter.
Air in system or
marginal water
flow.
Bleed/purge system as required. Confirm adequate pump size and
temp rise in the heat exchanger.
Slow combustion
air blower.
Check that CO
2
level is within specification.
Dirty burner/heat
exchanger.
Check pressure drop.
Low water flow due Refer to recommended piping for the respective boiler model.
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