PAGE 27of 46 HG-1-1701 GAS-FIRED HEATER
LAST UPDATED: JAN-25-2022 © SAMUEL JACKSON, INCORPORATED 2011 ALL RIGHTS RESERVED
GAS LOW PRESSURE --
The blower is on for this step. The SSOV1 and SSOV2 are
now used to test for presence of gas, adjust its pressure, test for valve leakage. The final
pressure should be between 2.5 and 3 PSI when the heater is operating.
With the gas cavity charged, leave the valves closed several minutes to see that the
pressure does not leak off. This tells us that the Safety Shutoff Valve SSOV2, is not
leaking. Evacuate the gas cavity. Leave the valves closed several minutes to see that the
pressure does not build up. This tells us that the upstream valve, SSOV1, is not leaking.
The operating program will perform similar tests every time the heater is shut down.
This is one reason electrical power must be supplied to the heater continuously, or at least
for 10 minutes after each shutdown.
In rare cases, the screen on the inlet to the SSOV block may become clogged with debris
from the gas supply. Evidence of this will be gas low pressure errors and a loss of heat
output while the pressure shown on Gas Pressure Gauge 2 (GPG2) is normal of about 3
PSI. The GPG1 pressure tap is upstream of the screen. To clean the screen, it is necessary
to remove the valve block from the flanged inlet and outlet pipe fittings.
IGT TRANSFORMER --
The blower will turn on when this test is entered, and it must
run 20 seconds to purge the duct system with air before this test can proceed. Turn on the
Ignition Transformer IGT. If the gin is quiet, you can hear the spark. If there is difficulty,
check the spark plug electrode gap at 1/16 to 1/8" (1.5 to 3 mm). Hold the IGT on for two
seconds while observing the flame light on the local panel LP. If the Flame Signal turns
on, it means that there is electrical interference between the spark plug wire and the flame
electrode wire. They should be run to the burner in separate conduits to avoid such
interference. Since the operating program makes a similar test before each ignition, the
burner will not operate until this problem is corrected. INTERFERENCE will flash on the
display if electrical interference occurs.
Try the Burner to see if it lights –
Try to start from the Home screen.
If flame fails during startup, Fuel Valve at Ignition position can be increased and try to
light again.
Screen on inlet to SSOV block
GPG2
SSOV
block
Summary of Contents for HG-1-1701
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