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Document: GFH-NT 1500-4000 IM 14 DEC 2016
Gas Fired Heater Instructions
©2016 NOVATEC, Inc. All Rights Reserved
10.0 NOVATEC GAS FIRED HEATER SEQUENCE OF OPERATION
A control box is attached to the gas fired process heater assembly. It contains the combustion
motor starter, ignition transform
er, burner controller, “Power” pilot light, and Disconnect switch. The
gas fired heater assembly, along with the desiccant dryer and drying hopper, makes a complete
drying system. There are two control boxes in this system. The first one is located on the
desiccant dryer. The second one is located on the gas heater. The process temperature set point
is programmed with the NOVATOUCH PLC Touch Panel; that is located on the desiccant dryer.
The process blower on the dryer is electrically interlocked with the gas-fired heater. If the process
blower turns off, the gas fired process heater will go to low fire (low heat mode). If the process
blower is off for longer than two minutes, the burner will automatically be turned off. Restarting the
burner requires the system to be manually reset. This is done by toggling the burner off/on switch
on the Gas Heater control box to the off position and then back on to reset the process blower
maximum off delay circuit.
1.0
When the main disconnect switch (1DISC) is closed, the control transformer (1T) is
energized along with the "Power" pilot light on the gas heater control panel.
2.0
The process blower on the desiccant dryer should be on to start the gas-fired heater. If
the process blower is not on, the process blower maximum off delay circuit may elapse,
and the flame controller will stop the sequence.
2.1
The Gas Heater Start Contact from the NOVATOUCH PLC desiccant dryer control
must be closed to start the burner. This contact is also toggled off and then on to reset
the process blower maximum off delay circuit if the process blower is off for more then
2 minutes.
2.2
If the Safety Interlocks, consisting of the gas heater start contact (CR), the low gas
pressure switch (LGPS), the high gas pressure switch (HGPS), the combustion air high
temperature limit switch (CHTL), the process air high temperature limit switch (PHTL),
the Dryer Process Blower maximum off delay timer contact (1TDRA), the combustion
blower motor starter overload contact (1OL), and the Combustion Blower Motor thermal
protector (TP) are all closed, the combustion blower will be energized by the burner
controller. If the combustion air pressure switch (APS) and the proof of closure switch
(POC) are closed, the air purge will begin. A neon indicator light will be on and is
visible through the clear plastic cover on the LGPS and HGPS when these switches are
closed. The POC has two indicator lights, orange showing that the valve is closed, and
green showing that the valve is open. The burner controller controls the air purge. The
total purge time is 1 minute.
2.3
If the CR, LGPS, HGPS, CHTL, PHTL, 1TDRA, 1OL, TP, and POC are not closed, the
sequence will not begin and the “Interlocks Closed” green LED on the flame controller
will not be on. If any or all open after the flame is on, the flame will go out, the green
“Interlocks Closed” LED will be off, and the sequence will not start until they are closed.
