Reznor RXH (Outdoor PreevA) Unit Installation Manual - Manual (Page 28)

Form I-RDH/REH/RHH/RXH (12-14), Page 28
Depending on the control option ordered (identified on the wiring diagram), the mix-
ing box may or may not have dampers. Depending on the configuration and controls,
dampers may be outside air only or outside and return air with manual or motorized
control. Damper motor may be 2-position, 3-position, or modulating and may be con-
trolled by unit operation, unit operation and a damper position dial (potentiometer),
discharge temperature, mixed inlet air temperature, building pressure, or a building
automation system.
Motorized dampers always close on shutdown.
TABLE 19 - Air Inlet and
Damper Controls by
Mixing Box Option
Mixing Box
Configuration
(see FIGURE 20)
Air Inlet Control
Option (Check
wiring diagram.)
Opening and
Dampers
Damper Motor Function
(damper position)
Dampers Controlled by
Option GD6
GE1
30% Outside and
100% Return Air
30% outside air maximum;
100% return air (no damper) Manual damper
GE2
2-position (open/closed) 30%
outside air damper; 100%
return air (no damper)
System control (switch or field-supplied time clock).
Option GD1 or
GD2
GE3 100% Outside Air
Opening only with
Dampers
2-position (open or closed) Unit operation.
GE4
3-position (2 open positions or
closed)
Unit operation with damper "stop" set by unit-mounted adjustable
damper dial (potentiometer).
Option GD4
NONE 100% Outside Air and Return Air Openings but no factory-installed dampers or controls.
GE5
100% Outside and
100% Return Air
Openings, both with
Dampers
None Damper controlled by a manual quadrant.
GE6
2-position (outside air open or
return air open)
System control (switch or field-supplied time clock).
*GE7
Return air temperature provides warm-up or cool-down by delaying
opening of outside air damper.
GE8
3-position (2 mixed positions or
return air only)
Unit operation with damper "stop" set by unit-mounted adjustable
damper dial (potentiometer).
GE10
Modulates outside air and
return air dampers to provide
mixture of outside and return
air in response to control
Unit operation with damper “stop” set from a remote adjustable
damper dial (potentiometer). Requires installation of shipped-separate
potentiometer; follow manufacturer’s instructions.
GE11 Discharge air temperature.
GE12
Discharge air temperature with unit-mounted adjustable damper dial
(potentiometer) set to always provide a minimum amount of outside
air.
*GE13
Discharge air temperature plus return air temperature setting to
provide warm-up or cool-down by delaying opening of outside air
damper.
*GE14
Discharge air temperature plus return air temperature providing
warm-up or cool-down by delaying opening of outside air damper
and with unit-mounted adjustable damper dial (potentiometer) set to
always provide a minimum amount of outside air after delay.
GE15
Building pressure. Requires installation of shipped-separate pressure
null switch. See page 29 and follow manufacturer's instructions.
GE16 DDC control from field-supplied automated building system
GE21
Applies to PREEVA ® systems with optional cooling operation; outside
air damper is controlled by enthalpy (heat content in a lb of air) using
an economizer logic module. On a call for low stage cooling if the
enthalpy of outdoor air becomes low, the outdoor air damper opens
to reduce the cooling load in the building. As enthalpy of outdoor
air increases, the outdoor air damper closes to a preset minimum
condition. During economizer operation, the mechanical cooling is
operated by stage 2 cooling on the space thermostat. The economizer
is automatically locked out during heating and holds the outdoor air
damper at the minimum position setting. Enthalpy sensor is shipped
separately for field installation in the outside air inlet. See instructions
beginning on page 29.
GE22
Applies to PREEVA ® systems with optional cooling. In cooling mode,
both outside air and return air dampers are modulated by enthalpy
(heat content in a lb of air) using an economizer logic module. On a
call for low cooling if the outdoor air enthalpy is lower than the return
air enthalpy, the outdoor air damper proportions open. If the outdoor
air enthalpy is higher than the return air enthalpy, the outdoor air
damper closes to minimum position. If outdoor air enthalpy and return
air enthalpy are equal, the outdoor air damper proportions open.
During economizer operation, the mechanical cooling is operated
by stage 2 cooling on the space thermostat. The economizer is
automatically locked out during heating and holds the outdoor air
damper at the minimum position setting. Enthalpy sensors are shipped
separately for field installation in the return air duct and the outside air
inlet. See instructions beginning on page 29.
*GE7 provides ASHRAE Cycle I; GE14 provides ASHRAE Cycle II; GE13 provides ASHRAE Cycle III
6.0 Mechanical
(cont’d)
6.4.5.3 Mixing Box Damper and Control Options
6.4 Unit Inlet Air
(cont’d)