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KN INSTALLATION AND OPERATION INSTRUCTIONS
Starting the boiler
(continued)
Figure 32
Throttle adjustment and flame window
Measure flame current
Electrical shock hazard
— The electrical box contains line-voltage
wiring and contacts. Use caution when working in the electrical box to
avoid contact with line-voltage elements. Power must be on to measure
flame current.
1. With the boiler operating at
low fire
(low-fire jumper in place), measure the flame
current.
2. Remove the upper electrical panel cover (upper right side of boiler).
3. Attach microammeter leads to the flame current test pins of the Fenwal ignition
module as in Figure 32.
4. The flame current should be approximately 6 microamps, and never less than
1 microamp. Record the flame current value on the back page of this manual.
5. If flame current is acceptable, continue with setup. If flame current is too low,
check the ignition electrode/flame rod assembly following the instructions in the
Maintenance section of this manual.
Check boiler modulation
1. Remove the low-fire jumper from the electrical connection panel (see Figure 28).
2. The boiler firing rate should change to meet demand. The HeatNet control display
will show the percentage of maximum firing rate (between 20% and 100%).
Test flame failure modes
Flame loss
1. With the boiler running in normal operation, close the manual gas valve on the
incoming gas line.
2. Within 0.8 second after the flame goes out, the boiler gas valve should shut off.
3. The HeatNet control will restart operation with prepurge, then continue through
a normal start cycle.
4. With the manual gas valve closed, the boiler should attempt ignition three times,
then lockout, as described below.
Ignition failure
1. Make sure there is a call for heat.
2. Turn the boiler on/off switch
OFF
.
3. Close the manual gas valve on the gas supply line.
4. Turn the boiler on/off switch
ON
.
5. The boiler should start a regular cycle.
6. When the boiler attempts ignition, no flame will occur. Within 4 seconds of
ignition start, the control will close the boiler gas valve and attempt another start.
7. After three failed ignition attempts, the Fenwal control will lockout.
8. The boiler will shut off and the HeatNet control display will show “LOCKOUT.”
9. Open the manual gas valve.
10. Reset the controls by turning the boiler on/off switch off, then on again.
11. The boiler should restart and operate normally.
Test control & interlock operation
Test HeatNet operating limit function
1. Allow the boiler to fire until the supply temperature reaches the upper end of the
control band.
2. The boiler should gradually cycle to minimum input (firing
rate = 20%), then turn off.
Test external controls
1. Lower the setting of external limit controls below the supply
water temperature. Verify that the controls shut down as
required.
2. Test operation of low water cut-offs, flow switches and other
external devices.
3. Test external gas pressure interlocks, if used.
4. Test/verify operation of combustion air dampers and end
switches, if used.
DHW applications
1. For DHW applications, verify that the boiler operates on
demand from the indirect water heater and shuts off as
required.
Fill out the installation certificate
1. Complete the checklist and installation certificate on the
back page of this manual.
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