Reznor DV Operation Manual (for units built before August 2003) - Manual (Page 14)

Form O-DV/RDF/ADF, P/N 148385, Page 13
lengthening or shortening the flame. The BTU output is varied (modulated) to
maintain the required discharge air temperature.
These modulating gas control options are electronic because in all cases the
gas valve acts to adjust the flow of the gas to the main burner in response to
DC volts emanating from an amplifier. When the DC voltage is between 0 and
5 volts, the main valve seat is closed. Low fire flow is accomplished through a
mechanical bypass. The low fire flow rate is set at the factory and should not
need adjustment. However, if adjustment is necessary, refer to the Maxitrol
literature that is included in the heater owner's envelope.
All of the electronic makeup air modulating gas control burner systems in-
clude low fire start. On an initial call for heat, the main burner ignites at its
lowest input. During mild weather, the burner may then cycle off. Such full
shutdown can be dictated by the outdoor ambient cutoff control. As the out-
side air temperature climbs above the setpoint of the outdoor ambient control,
the burner control circuit is de-energized. When moderately cold outside air
temperatures exist, the burner will modulate between low flame and high flame.
Low fire start and the outdoor ambient control prevent the makeup air system
from heating already warm air and providing "too much" heat to the building.
For troubleshooting guides and further explanation of Maxitrol Series 14 and
44 electronic modulation gas control systems, refer to the Maxitrol literature
in the owner's envelope.
The Option AG30, AG31, AG32, and AG35 electronic modulation systems
are comprised of Maxitrol Series 14 controls for makeup air. Options AG30
and AG31 systems electronically maintain a constant discharge air tempera-
ture in the range of 55-90°F. Option AG31 includes an overriding thermostat.
Option AG32 system will maintain a constant discharge air temperature in the
range of 80-130°F. Option AG35 maintains a discharge temperature range of
120-160°F.
FIGURE 21 - Maxitrol
Series 14 Components used
in Makeup Air Gas Control
Options AG30, AG31, AG32,
AG35
Amplifier, P/N 148590
Temperature Sensor
Mixing
Tube
Temperature
Selector
Option AG33 electronic modulation system is comprised of Maxitrol Series
44 controls for makeup air. The low limit (20-60°F) and the high limit (60-
140°F) for control of discharge air temperature are set at the amplifier located
in the control compartment. The space temperature is set at the remote
selectrastat (55-90°F range) located in the space. When the temperature is be-
low the space temperature setpoint, the control system operates the burner to
automatically adjust the discharge air temperature within the maximum and
minimum limits set on the amplifier.
FIGURE 22 - Maxitrol
Series 44 Components used
in Makeup Air Gas Control
Option AG33
Amplifier, P/N 157915
Temperature
Sensor,
P/N 119617
Mixing
Tube,
P/N 90323
Temperature
Selector, P/N 86990