74
Figure 12-5 Adjust outlet isolation valve
12
Maintenance
DIR #2000528875 00
ADJUST OUTLET
ISOLATION VALVE ONLY
Test low water flow conditions
NOTICE
This test is to be carried out once the
Noble Combi Boiler is completely
piped in with adequate gas and water
flow. Once the test is completed,
ensure that the isolation valve is
opened up to allow full water flow.
Test procedure
1. Place the boiler into the active position by pressing the
UP button for five (5) seconds (see page 57).
2. Hold
the
►
button plus the
▼
button for five (5)
seconds to enter Service Mode, allowing the unit to fire
up to 100% modulation.
3. Allow the unit to progress through its normal
diagnostics and pre-purge programming.
4. Allow the unit to fire and operate until the temperatures
stabilize. This occurs when the inlet and outlet
temperatures are rising together and the Delta T (
T) is maintained.
Installation & Service Manual
5. When the unit stabilizes, begin to slowly shut off the
isolation valve on the outlet piping of the boiler (see FIG.
12-5). This will begin to restrict the flow and simulate a low
flow condition.
6. While slowly shutting off the isolation valve, refer to the
Status Screen to watch the behavior of the boiler. This
screen allows you to monitor the inlet temperature, outlet
temperature, and
T.
7. When
the
T reaches 55˚F, the control will attempt to
modulate the firing rate down to protect it from low flow
conditions.
8. When
the
T reaches 60°F, the control module will turn off
the burner. If the control module shuts down, the test was
successful.
9. Completely open the isolation valve on the outlet piping of
the boiler.
10. Resume operation.
Figure 12-3 Remove flow sensor and flow switch
assembly
DIR #2000536540 00
REMOVE FLOW SENSOR
FLOW SWITCH
ASSEMBLY
Figure 12-4 Clean flow switch filter
BLOW AIR OR WATER INTO THE OPEN
END OF THE FLOW SWITCH FILTER
DIR #2000536591 00
F I R E T U B E C O M B I
™
