Safety Checks - Harsco Industrial MODU-FIRE FORCED DRAFT N750 Installation & Owner's Manual

3.10 S C
AFETY HECKS
The following checks of safety systems must be made before putting the boiler into normal operation.
Before firing the boiler refer to Sections 4.1 and 4.2 for information on the use of the controls, lighting, and shut-
down procedures.
checks described below.
reset to their proper settings.
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, indicator lights on the flame safeguard (pilot and main)
will illuminate indicating 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 assume 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 Flow Switch (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 boiler control panel will display "LOW FLOW/ILK". This is a manual reset error and the boiler should
not start until the pump is started and the control is reset.
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
Never attempt to operate a boiler that has failed to pass all the safety
After checking controls by manual adjustment, make sure they are always
MODU-FIRE® Forced Draft Gas-Fired Boiler
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