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MODU-FIRE® FORCED DRAFT
Gas-Fired Boiler Installation
3.11
SAFETY CHECKS
The following checks of safety systems must be
made before putting the boiler into normal opera-
tion.
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.
WARNING!
Never attempt to operate a boiler that has failed to
pass all the safety checks described below.
WARNING!
After checking controls by manual adjustment, make
sure they are always reset to their proper settings.
3.11.1 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. Dur-
ing this period, indicator lights on the flame
safeguard (pilot and main) will illuminate indi-
cating 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 program-
mer will assume a “Flame Failure” condition
and go to a “lockout” mode. Lockout will re-
quire manual reset of the flame safeguard.
After completing this test, turn off the boiler and
reconnect the wires to the main gas valve.
3.11.2 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. Red “Water Flow” light should illuminate after
a call for heat from the temperature control.
The boiler should not start until the pump is
started.
Perform appropriate tests on any external probe-type
low water cut-off.
3.11.3 Test of Limit Controls
Fire the boiler and test the high limit control as fol-
lows:
With the main burner operating, turn down the tem-
perature setting on the "high-limit" thermostat until
the main burner shuts off (the green "Heat" indicator
will go out). The high-limit switch must be manu-
ally reset after testing. A similar check should also
be made for the operating temperature control (see
Section 3.12 for instructions on setting this control).
After completion of these tests, re-adjust thermo-
stats to desired operating temperature and set high-
limit temperature, typically 20º F above operating
temperature.
3.11.4 Test of Low Gas Pressure Switch
Manual Reset
Gas Pressure Switch
18