Staged Air Volume Control - 2 Speed Fan With Variable Frequency Drive (Vfd); Staged Air Volume (Sav™) Indoor Fan Speed; System; Identifying Factory Option - Carrier WeatherMaster 50HC04 Service And Maintenance Instructions

Fig. 14 — Tightening Locking Collar
STAGED AIR VOLUME CONTROL — 2 SPEED
FAN WITH VARIABLE FREQUENCY DRIVE
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 automat-
ically adjust the indoor fan motor speed in sequence with the
unit's ventilation, cooling and heating operation. Per ASHRAE
(American Society of Heating, Refrigerating, and Air-Condi-
tioning Engineers) 90.1-2016 standard section 6.4.3.10.b,
during the first stage of cooling operation the SAV system will
adjust the fan motor to provide two-thirds (
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

Identifying Factory Option

This supplement only applies to units that meet the criteria de-
tailed in Table 3. If the unit does not meet that criteria, discard
this document.
Table 3 — Model-Size / VFD Option Indicator
POSITION IN
MODEL / SIZES
MODEL NUMBER
50HC / 07-28
See Appendix A for an example of model number nomenclature.

Unit Installation with SAV Option

50HC ROOFTOP
Refer to the base unit installation instructions for standard re-
quired operating and service clearances.
IMPORTANT: The remote VFD keypad is a field-installed
option. It is not included as part of the factory-installed VFD
option.
See "Variable Frequency Drive (VFD) Installation, Setup and
Troubleshooting Supplement" for wiring schematics, perfor-
mance charts, and configuration.
See Fig. 15-17 for locations of the variable frequency drive
(VFD) as mounted on the various 50HC models.
LOCKING COLLAR
T--- 25 TORX SOCKET
HEAD CAP SCREW
(VFD)
/ ) of the design
2
3
2 / speed.
3
VFD FIOP
INDICATOR
17 G, J
VARIABLE
FREQUENCY
DRIVE (VFD)
Fig. 15 — VFD Location for Sizes 07-09
VARIABLE
FREQUENCY
DRIVE (VFD)
Fig. 16 — VFD Location for Size 12
VARIABLE
FREQUENCY
DRIVE (VFD)
Fig. 17 — VFD Location for Size 14
ADDITIONAL VARIABLE FREQUENCY DRIVE
(VFD) INSTALLATION
AND TROUBLESHOOTING
Additional installation, wiring, and troubleshooting informa-
tion for the Variable Frequency Drive can be found in the fol-
lowing manual: "Variable Frequency Drive (VFD) Installation,
Setup and Troubleshooting Supplement."
8