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GENERAL
Staged Air Volume (SAV™)
Indoor Fan Speed System
The Staged Air Volume (SAV) system utilizes a Fan Speed control
board and Variable Frequency Drive (VFD) to automatically ad-
just the indoor fan motor speed in sequence with the unit's ventila-
tion, cooling and heating operation. Per ASHRAE 90.1-2016 and
IECC
1
-2015 standards, during the first stage of cooling operation
the SAV system will adjust the fan motor to provide 66% of the
design airflow rate for the unit. When the call for the second stage
of cooling is required, the SAV™ system will allow the design air-
flow rate for the unit established (100%). During the heating
mode, the SAV system will allow total design airflow rate (100%)
operation. During ventilation mode, the SAV system will operate
the fan motor at 66% of full speed.
Figures 1, 2 and 3 show the VFDs used for the SAV indoor fan
speed system.
Fig. 1 — ACH550 Variable Frequency Drive (VFD)
Table 1 — Model Size/VFD Option Indicator
MODEL/SIZES
48/50TC / 07-30
50TCQ / 07-24
48/50HC / 07-28
50HCQ / 07-12
40RUA / 07-30
40RUS / 08-30
40RUQ / 07-25
1. Third-party trademarks and logos are the property of their respective
owners.
POSITION IN
VFD FIOP
MODEL NUMBER
INDICATOR
17
G-M
17
G-M
17
G-M
17
G-M
9
T
9
T
9
T
Fig. 2 — ACS320 Variable Frequency Drive (VFD)
Fig. 3 — ACH580 Variable Frequency Drive (VFD)
Identifying Factory Option
This supplement only applies to units that meet the criteria de-
tailed in Table 1. If the unit does not meet that criteria, discard this
document.
NOTE: See Fig. 4 and 5 for examples of typical Model Number
Nomenclature.
NOTE: 48/50LC units are not covered in this document; VFDs are
standard equipment on belt drive LC units. VFD instructions for
the 48/50LC series are found in the Service and Maintenance
Instructions for the LC base units.
2
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