Comfort-Aire HMB**V*1E SERIES - Manual (Page 12)

12
Blower Configurations
Selecting Minimum Electric Heat Airflow
The minimum electric heat airflow setting controls the
minimum air flow that will be produced whenever electric
heater kits are used. When the electric heater kit is
energized along with a heat pump, the airflow may be
higher depending on the basic cooling/heat-pump airflow
setting. The minimum electric heat airflow is selected
by the red blower wire on 3-speed models or setting
switches 1,2,3 & 4 on HMB**X*1E models. HMB**V*1E
models automatically set the heating speed based on the
amount of installed heat. The remaining 3 HEAT switches
have no function. Switch settings are listed in Tables 6 or
9 (pages 19 & 21).
NOTE: For HMB**X*1E models, the
minimum electric heat airflow setting may be set higher,
but must never be set lower than the setting shown in
Table 6 (page 19).
Determining Nominal System Capacity
To select the appropriate airflows for the air handler, the
nominal system capacity must be known. The nominal
system capacity is always the nominal capacity of the
outdoor unit. However, in some situations the nominal
system capacity may not be the same as the nominal
capacity of the air handler. Always refer to the nominal
capacity of the outdoor unit to determine the nominal
system capacity.
NOTE: The CFM values listed in Table 8 (page 20) are
not dependent on duct static pressure. The VSHE motor
automatically compensates for changes in duct static
pressure (within the limits of the motor).
3-Speed Units
The blower speed is preset at the factory for operation
at the same speed for heating and cooling, by using the
jumping terminal on the blower motor and connecting it
to the desired speed with both the red and black wires
connected to the jumping terminal. NOTE: The control
board is programmed with a 40 second off delay in the
cooling mode for optimum system performance and
efficiency.
CAUTION:
To avoid personal injury or property damage,
make sure the motor leads do not come into
contact with any uninsulated metal components
of the unit.
For optimum system performance and comfort, it may be
necessary to change the factory set speed. See Table 4
(page 17) for airflow data. To change the blower speed:
1. Disconnect all electrical power to the unit and remove
the upper door.
2. Remove the black and red wires from the blower motor
jumping terminal. Discard the blower motor jumping
terminal.
3. Connect the heating speed wire (red) and the cooling
speed wire (black) to the desired blower speed marked
on the terminal block of the blower motor.
• Terminal 4 = Hi speed
• Terminal 5 = Med speed
• Terminal 6 = Low speed
4. Replace the upper door and secure it to the unit.
5. Restore power to the unit.
High Efficiency Units (Variable & Fixed Speed)
IMPORTANT! This air handler has been designed to
give the installer maximum flexibility to optimize system
performance, efficiency, and comfort. Because there are so
many different ways to set up the air handler it is important
to read and follow these directions carefully.
HMB**X*1E, & HMB**V*1E Series air handlers use high
efficiency circulating air motors that come in two variations
and both are controlled differently. The fixed speed motor
control board (Figure 13, page 24) controls the torque
and the variable speed motor control board (Figure 14)
controls the airflow at a constant CFM. Both boards use
the same control board.
Before operation, the air handler must be configured to
match the unit with the system, system options, and climatic
conditions. When configured, the air handler responds
directly to the thermostat inputs, as well as the optional
humidistat (see page 13). During normal operation, the
motor will gradually change speeds during start-up, shut
down, when thermostat inputs change, and when the duct
static pressure changes (vents closed or opened, filter
clogging, etc.). The air handler is configured by setting
the selector switches and removing jumper connectors.
Selecting Basic Heating Airflow
Fixed & variable speed motor control boards (Figures 13
& 14) contain a set of dip switches for setting the blower
speed. For HMB**X*1E Series models, pins 1-4 set the
speed for heating. For HMB**V*1E Series models, the
A/B switch must be set for the appropriate air handler
size (either setting can be used for 48K or 60K BTUH
applications). The airflow is set automatically based on
the amount of installed heat. For both HMB**X*1E, &
HMB**V*1E models, the cooling speed is selected via
switches 5,6,7,& 8. To determine the appropriate switch
settings for your installation, see Tables 5 - 8 (pages 18-20).
Selecting Basic Cooling / Heat Pump Airflow
The basic cooling/heat-pump airflow is controlled by setting
switches 5 - 8 on the motor control board (mounted on the
blower). All airflows for other modes of operation (except
electric heat) are determined by this basic setting. FAN
ONLY would deliver 50% of the selected cooling airflow.
Table 5 lists the basic airflow values versus the airflow
selector switch settings and ranges of basic air flow
settings recommended for each nominal system capacity.
• When operating in the heat pump mode, a higher basic
airflow setting will increase the energy efficiency and
capacity but will also decrease the supply air temperature.