Greenheck PVF/PVG Indirect Gas-Fired Heat Modules (474645) - Manual (Page 5)

Indirect Gas-Fired Heat Modules 5
®
Microprocessor
The microprocessor provides the call for heat to the
ignition controller and also
monitors the discharge air
temperature. It is found only
in the unit main control center.
On units with electronic
modulation, it also determines
the required burner firing rate.
Discharge Air Temp Sensor
This sensor is shipped with all
units and must be field-installed in
the discharge air duct. This may
be located in the main unit control
center or the furnace control center
depending on the control type.
Input Converter
The input converter takes an analog signal from a
microprocessor or a BMS
and converts it to a control
signal that can be used
by the FX programmable
controller. It is found in the
furnace control center.
FX Programmable Controller
Used on all 4:1 electronic
modulating controls and
8:1 staged turndown.
The FX controller turns on and
electronically modulates gas
valves. It will also enable the
ignition module. The FX controller has a digital readout
and four push buttons, one for Function, one for Enter
and two for scrolling up or down. It is pre-programmed
at the factory for each specific furnace configuration
and it may be used to control two furnaces at the same
time.
Ignition Controller
This controller is found only in the furnace control
center. It has an LED indicator
light on the top right of the
controller that will flash GREEN
for normal operation or RED
for an error. Some furnace
configurations have two of
these controllers.
Burner Manifold
Airflow Switch
Airflow switches are used on both
furnaces and are found on the furnace
vest plate. If the combustion blower
is multi-speed, there will be two of
them and each will switch in response
to a different pressure. The switch is
connected to the combustion blower
by means of a vacuum tube and is used to sense
operation of the combustion blower. The internal switch
is Normally Open (NO). If the blower fails to operate, the
open circuit will cause the ignition controller to disable
the furnace.
Flame Igniter
The igniter receives a high voltage
input from the ignition controller to
produce a spark between the two
electrodes. It operates only during
the ignition phase. On split burner
manifolds, there will be two igniters.
Flame Sensor
The flame sensor is identical to the flame igniter. It is
located on the opposite end of the burner manifold from
the igniter.
Auto Reset High Temperature
Limit Switch
This limit switch is installed through the
vest plate into the supply air plenum.
A350 and S350 Control System
Used on two stage and
single stage controls. Used
in conjunction with a field-
installed remote temperature
sensor. Has an LED indicator
light to show when the
output relay is energized.
When used with multiple
stages, the S350 controller is
used for the extra stages.
Typical Furnace, Electrical and Control Components
S350
Controller
A350
Controller
Single Section
Burner Manifold
Split Burner
Manifold