Step 8 — controls options – Carrier 48AJ User Manual
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Size gas-supply piping for 0.5-in. wg maximum pressure
drop. Do not use supply pipe smaller than unit gas connection.
OPTIONAL STAGED GAS UNITS — The staging pattern
is selected based on Heat Stage Type (HTSTGTYP). Max
Capacity per changes default value is selected based on Capac-
ity Maximum Stage (CAPMXSTG). See Table 4.
For complete information and service instructions for
Staged Gas Control Units, see Control Operation and Trouble-
shooting literature.
Step 8 — Controls Options —
The control options
that the units can provide are based on the following parame-
ters: CV (constant volume) or VAV (variable air volume) oper-
ation; stand-alone unit with field-supplied sensors installed
(CV or VAV); as a system via Carrier Comfort System (TEMP
or VVT® [Variable Volume and Temperature]); optional elec-
tronic expansion board installed (CV or VAV); linked to the
Carrier Comfort Network; availability of a computer and soft-
ware (ComfortWORKS® Building Supervisor, and Service
Tool) or remote enhanced display accessory installed to access
the base control board; and optional factory-installed staged
gas control. See Table 5.
NOTE: Access to the base control board allows unit occu-
pancy schedules, unit timeclock, and various set points to be
changed from their factory-defined default settings.
Table 4 — 48A,E Series Staged Gas Implementation
IMPORTANT: Natural gas pressure at unit gas connection
must not be less than 5 in. wg or greater than 13.5 in. wg.
NUMBER OF STAGES
MODEL NUMBER POSITION
POSITION
HEAT SIZE
3
5
6,7,8
HTSTGTYP
CAPMXSTG
5 stages
E
S
024
028
030
034
038
044
048
Default=1
Default=20
Low
A
S
020
025
027
030
035
040
050
Default=1
Default=20
Low
E
T
038
044
048
Default=1
Default=20
High
A
T
035
040
050
Default=1
Default=20
High
7 stages
E
T
024
028
030
034
Default=2
Default=15
High
A
T
020
025
027
030
Default=2
Default=15
High
9 stages
E
T
054
058
064
068
Default=3
Default=15
High
A
T
060
Default=3
Default=15
High
11 stages
E
S
054
058
064
068
Default=4
Default=15
Low
A
S
060
Default=4
Default=15
Low
Fig. 23 — Field Gas Piping