SAMUEL JACKSON HG-1-1501, Service And Operation Manual

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PAGE 24 of 46 HG-1-1501 GAS-FIRED HEATER
© SAMUEL JACKSON, INCORPORATED 2011 ALL RIGHTS RESERVED
GAS ACTUATOR – The blower is on for this test. The actuator motor of the
modulating temperature control valve GVM is powered up. Turn selector to “+” to drive
the motor to the open position. Turn selector to “-“ position to drive the valve to the
closed position. This test checks the integrity of the 4-20mA DC control signal going
from the PLC to the valve and checks the operation of the valve. The AIR SP (set point
temperature) needs to be adjusted to at least 150F for this test to work well since the PLC
will generate a full 20mA signal for full valve travel at higher set points.
The Gas Valve Motor (GVM) has been adjusted at the factory for correct travel. If
replacement of GVM is necessary in the future, refer to the picture below for the
adjustment of the three color coded rings under the cover of the motor.
Rotate the three
color rings so the
tabs are in the
positions shown here
GVM Gas Valve Motor adjustment
Tip indicates
butterfly position in
valve. Position
shown is closed
(0%).