0-30% Outdoor Air Damper Control; Minimum Ventilation Control; Economizer; Temperature Control - McQuay MicroTech II Operation Manual

0-30% Outdoor Air Damper Control

Minimum Ventilation Control

Table 32: Programmable Parameters
Keypad/Display ID
Menu Name Item Name
MinOA Type= None
OA Damper
MinOA Pos= 10%
Whenever the unit is in the Fan Only, Cooling, Heating or
Min DAT operating state, the outdoor air dampers are pre-
vented from closing below the Minimum Outdoor Damper
Position Set Point.
During the Off, Startup, Recirc, and MWU operating states,
the outdoor air dampers are driven continuously to 0%.
Unoccupied Operation
Whenever the unit is operating in the unoccupied operating
states UnocEcon, UnocClg, or UnocHtg, the outdoor air
dampers are driven continuously to 0%.
No Minimum OA Reset
With the 0-30% OA Damper arrangement, the Minimum
Outdoor Damper Position Reset Flag can only be set to
"None". The dampers are always control to the Minimum
Outdoor Damper Position Set Point except as noted in the
previous section when they are continuously driven to 0%.
Network OA Reset
When the Minimum Outdoor Damper Position Reset Flag is
set to "None", the Minimum Outdoor Damper Position Set
Point can be reset between 0-30% via a network signal.
100% Outdoor Air Damper Control
When a unit is equipped with a 100% outdoor air hood, the
outdoor air dampers are driven open continuously whenever
the unit enters the Startup operating state. If they are not
open (above 50%) at the end of the Startup operating state or
any time afterward while the fans are running, the unit is
shutdown on the OA Dmpr Stuck fault.
When the unit is shut down, the dampers remain open for 30
seconds after the unit airflow switch opens up indicating loss
of airflow.
Note: The dampers remain open in the event that the air-
flow switch does not open after the fans are shut
down.
68

Economizer

Temperature Control

Table 33: Programmable Parameters
Parameter Name
Minimum Outdoor
Damper Position
Reset Flag
Minimum Outdoor
Damper Position Set
Point
Discharge Cooling
Zone Temp Setup
Compressor Setup
Economizer Setup
Entering Econo Operating State
If a unit is equipped with a 0-100% modulating economizer,
and economizer operation is available (refer to "Economizer
Changeover Method" on page 69) the unit attempts to satisfy
the cooling load by using outdoor air before using mechani-
cal cooling. When this is the case, the unit enters the Econo
operating state when the Ctrl Temp= value rises above the
Effective Cooling Enable Set Point by more than half the
Cooling Enable Dead Band.
Note:
There are two processes involved in the Economizer control
function. The first is the process of modulating the outdoor
air dampers to maintain the Effective Discharge Cooling Set
Point. The second is the process of adjusting the Effective
Discharge Cooling Set Point up and down between the Mini-
Keypad/Display ID
Menu Name Item Name
Eff Clg Spt= ____ °F
Zone Cooling Occ Clg Spt= 75.0 ºF
Clg Deadband= 1.0 ºF
Eff Clg Spt= ___ ºF
Clg Db= 1.0 ºF
Min Clg Spt= 55.0 ºF
Max Clg Spt= 65.0 ºF
Clg Propbd= 8.0ºF
Clg IntTime= 700 sec
Period= 60 sec
Stage Timer= 5 min
Clg Propbd= 30.0 ºF
Clg IntTime= 100 sec
Clg Period= 30 sec
Unless it is set by a signal from an optional space
temperature sensor, the Effective Cooling Enable
Set Point is set by the controller equal to the Cool-
ing Enable Set Point.
Parameter Name
Effective Cooling
Enable Set Point
Cooling Enable Set
Point
Cooling Enable Dead
Band
Effective Discharge
Cooling Set Point
Discharge Cooling
Dead Band
Minimum Discharge
Cooling Set Point
Maximum Discharge
Cooling Set Point
Zone Cooling Propor-
tional Band
Zone Cooling Integral
Time
Zone Control Period
Cooling Interstage
Timer
Economizer Cooling
Proportional Band
Economizer Cooling
Integral Time
Economizer Cooling
Period
OM 138