Carrier 38APS025 - Configuring Outside Air Temperature Reset; Outside Air Temperature Reset

131
Outside Air Temperature Reset
— The 38AP units are
shipped with an outside air sensor, so no additional sensors are
required.
To use Outside Air Temperature Reset, four variables must
be configured. In Configuration
o
RSET, set these items:
• Cooling Reset Type (CRST): Configure for the type of
reset desired, Outside Air Temperature
• Remote – No Reset Temp (RM.NO): Set to the tempera-
ture that no reset should occur
• Remote – Full Reset Temp (RM.F): Set to the tempera-
ture that maximum reset is to occur
• Remote – Degrees Reset (RM.DG): Set to the maximum
amount of reset desired
The Outside Air Temperature Reset example shown in Table
60 and Fig. 151 and 152 provides 0° F (0° C) reset to the
Active Set Point (Run Status
o
VIEW
o
SETP) if Outside Air
Temperature (Tem pera tures
o
UNIT
o
OAT)=85 F (29.4 C)
and 6 F (3.3 C) reset if OAT=55 F (12.8 C). Using these val-
ues, if SETP=55 F (12.8 C) and OAT=55 F (12.8 C) or less,
the Control Point (Run Status
o
VIEW
o
CTPT) will reflect
6° F (3.3° C) reset or 61 F (16.1 C). If OAT=85 F (29.4 C) or
more, the control point Run Status
o
VIEW
o
CTPT will
reflect 0° F (0.0° C) reset or 55 F (12.8 C). Between
OAT=55 F (12.8 C) and OAT=85 F (29.4 C) a proportional
reset amount will be applied to CTPT.
Table 60 — Configuring Outside Air Temperature Reset
*Not supported.
CONFIGURATION
o
OPT2
ITEM EXPANSION COMMENTS EXAMPLE VALUE
C.TYP Machine Control Type
Range: 1 to 9
1 (VAV)
3 (Tstat Multi)
4 (Tstat 2stg)
5 (SPT Multi)
7 (PCT Cap)
8 (Dual Tstat)
9 (VAV Setpoint)
Default: 4
Value must be set to 1, 3, 5 or 9
1, 3, 5 or 9
CONFIGURATION
o
RSET
CRST Cooling Reset Type
0=No Reset (Default)
1=4-20 Input
2=Out Air Temp
3=Return*
4=Space Temp
2
RM.NO Remote – No Reset Temp
Range: 0.0 to 125.0 F
(–17.8 to 51.7 C)
Default: 125.0 F (51.7 C)
85.0 F (29.4 C)
RM.F Remote – Full Reset Temp
Range: 0.0 to 125.0 F
(–17.8 to 51.7 C)
Default: 0.0 F (–17.8 C)
55.0 F (12.8 C)
RM.DG Remote – Degrees Reset
Range: –30.0 to 30.0 'F
(–16.7 to 16.7 'C)
Default: 0.0 'F (0.0 'C)
6.0 'F
(3.3 'C)