Harsco Industrial 1004905923 Installation & Owner's Manual page 27

their proper settings. Verify proper operation after servicing.
3.10.1 Test of Ignition Safety System
Test the ignition system safety shutoff as follows:
1. Remove the black plug/connector from the main gas valve (it is held on with a central screw).
2. With the main gas cock (inlet manual gas valve) open, the burner should be cycled on. After all the safety
limits such as gas pressure, water flow and temperature are satisfied, the blower will run and pre-purge the
boiler.
3. Once the purge is complete (30 seconds), the ignition transformer will be energized. There will be a 4 second
trial for ignition period. During this period the boiler is attempting to light.
4. The main gas valve will not open because there is no power to the valve due to the disconnected wires.
Hence, no flame will be established and the flame safeguard will not receive a flame signal from the UV
scanner.
5. After 4 seconds, the flame safeguard programmer will recognize a "Flame Failure" condition and go to a
"lockout" mode. Lockout will require manual reset of the flame safeguard.
After completing this test, turn off the boiler and reconnect the wires to the main gas valve.
3.10.2 Test of Low Water Cut-off
The boiler is furnished with a flow-switch-type low water cut-off in the outlet nozzle. Test as follows:
1. Turn boiler and then system pump off.
2. Turn boiler back on.
3. The red "Low Water" light should illuminate and the boiler should not start.
Perform appropriate tests on any external probe-type low water cut-off.
3.10.3 Test of Limit Controls
Fire the boiler and test the high limit control as follows:
With the main burner operating, turn down the temperature setting on the "high-limit" thermostat (located in the
control panel below the digital operating control) until the main burner shuts off. The high-limit switch must be
manually reset by pushing the small green lever. A similar check should also be made for the digital operating
temperature control (see Section 3.11 for instructions on setting this control). After completion of these tests, re-
adjust the operating thermostat to the desired operating temperature and set high-limit temperature, typically 20º
F above operating temperature.
After checking controls by manual adjustment, make sure they are always reset to
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MODU-FIRE Forced Draft Gas-Fired Boiler 2500-3000
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