Reznor ADFH Operation Manual - Manual (Page 12)

Form O-ADF/RDF, P/N 148385R2, Page 12
3.0 Operation
and Service
(cont'd) The electronic modulating-type gas controls act in response to discharge and/or room
air temperature sensors to change the gas flow rate to the burner, thus 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 emanat-
ing 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 adjust-
ment 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 include 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 out-
door ambient cutoff control. As the outside air temperature climbs above the setpoint
of the outdoor ambient control, the burner control circuit is de-energized. When mod-
erately 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 elec-
tronic 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 com-
prised of Maxitrol Series 14 controls for makeup air. Options AG30 and AG31 systems
electronically maintain a constant discharge air temperature 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 20 -
Modulating Gas
Valve - Options
AG30, AG31, AG32,
AG33, AG35, AG36
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 AG36 is a special application gas train that is designed for controlling the envi-
ronment of a paint booth operation. The system includes a Maxitrol A1494 amplifier,
discharge air temperature sensor, dual remote discharge air temperature selector (dry-
ing selector 80-140°F and a spray selector 60-90°F), and two switches to control the
operation of the modulating gas valve.
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
3.6 Gas Train Including Burner, Gas Controls, Manifold
Arrangements, and Gas Pressure Switches (cont'd)
Option AG33 electronic modulation system is comprised of Maxitrol Series 44 con-
trols 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 below the space temperature setpoint, the con-
trol system operates the burner to automatically adjust the discharge air temperature
within the maximum and minimum limits set on the amplifier.