Finned copper tube gas boilers & water heaters – Boiler Manual
30
COMBUST AIR DAMPER:
If the combustion air damper has been
selected for use (MASTER BOILER, AUX FUNCTIONS), and
the proof switch does not make, this fault will be displayed.
When the combustion air damper is used, the master’s BOILER3/
DAMPER relay contacts at J13 are closed. These should be wired
to the combustion air damper or preferably an isolation relay. The
prove switch on the combustion air damper must be wired to J10B,
SPARE 1.
FAULT
SYSTEM SET
160˚F
COMBUSTION AIR DAMPER
When the master boiler receives a call for heat and needs to start
a boiler, the BOILER3/DAMPER relay K5 closes. At the same
time, the boiler is started, fires, and continues to fire. If the
combustion air damper does not prove within the proof time
specified in the combustion air damper menu, the boiler will shut
down and display the fault. The fault on the Master boiler can be
cleared by removing the call for heat on the master boiler and fixing
the combustion air damper problem. A combustion damper fault
on a Member boiler can only be cleared by power cycling.
The Master boiler controls a system damper and Member boilers
control their own respective dampers. When the call for heat is
removed, the damper will remain open for 30 seconds before closing.
This allows for post purge cycles to complete.
OPEN ***** SENSOR:
If the open sensor fault is displayed, the
sensor in the position reported was originally detected, but has since
opened. The boiler will shut down on any OPEN sensor.
FAULT
SYSTEM SET
160˚F
OPEN OUTSIDE SENSOR
SHORTED ***** SENSOR:
If the shorted sensor fault is
displayed, the sensor in the position reported was originally detected,
but has since shorted. The boiler will shut down on any SHORTED
sensor.
FAULT
SYSTEM SET
160˚F
SHORTED OUTSIDE SENSOR
DELTA TEMP > 40°F:
If the temperature across the heat
exchanger rises above the maximum designated temperature for
the FIII model boiler, a warning or fault will be displayed. This
protection is required to prevent damage to the heat exchanger in
the event high differential temperatures are encountered. The fault
or warning condition may be changed in the AUX FUNCTIONS
menu under ALARM TYPE. The default condition is WARNING
with LIM->HALF RATE = YES.
When this condition exists and the ALARM TYPE is set to
WARNING and LIM-> HALF RATE, the boiler is limited to 1/2
it’s input rate. So, if the boiler is trying to fire at 80%, the rate is
limited to 40% until the temperature across the heat exchanger falls
at least 10°F below the maximum designated temperature for the
FIII boiler model. In this case: 40°F - 10°F = 30°F.
If the ALARM TYPE is set to FAULT, the boiler will display the
FAULT message and this condition will be treated as an interlock,
thus shutting down the boiler until the Delta Temp drops 10°F
below the maximum designated temperature.
1/2 INPUT
DELTA TEMP > 40°F
LOCAL SET
41˚F
RETURN TEMP < 130°F:
If the Return Inlet temperature is
less than 130°F this warning will be displayed. This warning does
not affect operation and does not set the alarm relay. A log entry is
made to aide in diagnosing why this may be occuring. Condensing
will occur with return temperatures below 130°F and a shortened
heat exchanger life will occur.
PREPURGE
RETURN TEMP < 130°F
LOCAL SET
41˚F
