McQuay MicroTech III RAH User Manual

McQuay OM 920-1 25
Keypad/Display Menu Structure
On CAV units the Ventilation Limit and the Demand Control Ventilation Limit are fixed
values set equal to the Vent Limit= and DCV Limit= parameters. On VAV units the OA
Damper Position increases from the Vent Limit= value to the LoFloVent Limit= value as the
VFD speed goes from 100% down to the Min Clg Spd= value. The Demand Control
Ventilation Limit in this VAV case is determined by the Ventilation Limit X DVC Limit=/Vent
Limit=. When the Min OA Reset= parameter is set to “None” the Min OA Pos= value is set to
the Ventilation Limit. If Min OA Reset= is set to Network, Ext VDC, Ext mA, IAQ VDC, or
IAQ mA, the Min OA Pos= varies between the Ventilation Limit and the Demand Control
Ventilation Limit as the reset signal varies from its maximum to minimum value.
Vent L imit is an adjustable item that sets the value of the Ventilation Limit on a CAV unit or
when a VAV unit is at 100% discharge fan speed.
DCV Limit is an adjustable item that sets the value of the Demand Control Ventilation Limit
on a CAV unit or when a VAV unit is at 100% discharge fan speed. This item is only used
when the “Min OA Reset=” is set to something other than “None.”
Min OA Reset is an adjustable item that sets the type of minimum OA damper position reset
to be used. When this is set to “None” the Min OA Pos= parameter is set to the Ventilation
Limit. When this is set to “Network,” “Ext VDC,” “Ext mA,” “IAQ VDC,” or “IAQ mA” then
the Min OA Pos= parameter varies from the Ventilation Limit down to the Demand Control
Ventilation Limit as the reset signal goes from its maximum to minimum value.
Design Flow is an adjustable item used to turn the optional DesignFlow outdoor airflow
measuring reset function on and off. This is one of several available methods of automatically
resetting the Min OA Pos parameter.
OA @ MinV/mA is is an adjustable item used when Min OA Reset is set to “Ext VDC” or
“Ext mA” to define at what percent of the field input signal the Min OA Pos is to be at the
Demand Control Ventilation Limit value.
OA @ MaxV/mA is an adjustable item used when Min OA Reset= is set to “Ext VDC” or
“Ext mA” to define at what percent of the field input signal the Min OA Pos= is to be at the
Ventilation Limit value.
Min V/mA is an adjustable item used to set the minimum value of the field input signal.
Max V/mA is an adjustable item used to set the maximum value of the field input signal.
PPM @ DCV Limit is an adjustable item used when Min OA Reset= is set to “IAQ VDC” or
“IAQ mA” to define at what PPM value the Min OA Pos= is to be at the Demand Control
Ventilation Limit value.
PPM @ Vent Limit is an adjustable item used when Min OA Reset= is set to “IAQ VDC” or
“IAQ mA” to define at what PPM value the Min OA Pos= is to be at the Ventilation Limit
value.
PPM is a status only item which indicates the current reading from the CO2 sensor.
Min PPM is an adjustable item that sets the minimum PPM value.
Max PPM is an adjustable item that sets the maximum PPM value.
V/mA @ Min PPM is an adjustable item that sets the minimum PPM value and the minimum
DC voltage or mA value of the CO
2
sensor used when Min OA Reset= is set to “IAQ VDC” or
“IAQ mA.”
V/mA @ Max PPM is an adjustable item that sets the maximum PPM value and the
maximum DC voltage or mA value of the CO
2
sensor used when Min OA Reset= is set to
“IAQ VDC” or “IAQ mA.”
Min Fan Diff is an adjustable item which sets a differential between the discharge and return
fan capacities above which the minimum allowable Min OA Position begins to be reset
upwards from the Demand Control Ventilation Limit toward the Ventilation Limit.

McQuay MicroTech III RAH Specifications

General

Brand	McQuay
Model	MicroTech III RAH
Category	Controller
Language	English