Bryant 549B User Manual
Page 19
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19
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Table 7 — CO
2
Sensor Standard Settings
LEGEND
ppm — Parts Per Million
Dehumidification of Fresh Air with DCV Control
Information from ASHRAE indicates that the largest humid-
ity load on any zone is the fresh air introduced. For some
applications, an energy recovery unit is added to reduce the
moisture content of the fresh air being brought into the
building when the enthalpy is high. In most cases, the nor-
mal heating and cooling processes are more than adequate to
remove the humidity loads for most commercial applications.
If normal rooftop heating and cooling operation is not ade-
quate for the outdoor humidity level, an energy recovery unit
and/or a dehumidification option should be considered.
VII. STEP 7 — ADJUST INDOOR-FAN SPEED
Adjust the indoor-fan speed to meet jobsite requirements.
For units with electric heat, required minimum cfm is
2250 for 549B090 and 102 and 3000 for 549B120 with the
following exceptions:
Table 8 shows indoor-fan motor data. Table 9 shows fan rpm
at motor pulley settings for standard and alternate motors.
Tables 10 and 11 show FIOP/accessory static pressure. Refer
to Tables 12-23 to determine fan speed settings. Fan motor
pulleys are factory set for speed shown in Table 1.
To change fan speeds:
1. Shut off the unit power supply and tag disconnect.
2. Loosen belt by loosening fan motor mounting nuts
See Fig. 31 and 32.
3. Loosen the movable pulley flange setscrew (see
Fig. 33).
4. Screw the movable flange toward the fixed flange to
increase speed and away from the fixed flange to
decrease speed. Increasing fan speed increases the
load on the motor. Do not exceed the maximum speed
specified in Table 1.
5. Set the movable flange at the nearest keyway of the
pulley hub and tighten the setscrew. (See Table 1 for
speed change for each full turn of the pulley flange.)
To align fan and motor pulleys:
1. Loosen the fan pulley setscrews.
2. Slide the fan pulley along the fan shaft.
3. Make angular alignment by loosening the motor from
the mounting plate.
SETTING
EQUIPMENT
OUTPUT
VENTILATION
RATE
(cfm/Person)
ANALOG
OUTPUT
CO
2
CONTROL RANGE
(ppm)
OPTIONAL
RELAY SETPOINT
(ppm)
RELAY
HYSTERESIS
(ppm)
1
Interface w/Standard
Building Control System
Proportional
Any
0-10V
4-20 mA
0-2000
1000
50
2
Proportional
Any
2-10V
7-20 mA
0-2000
1000
50
3
Exponential
Any
0-10V
4-20 mA
0-2000
1100
50
4
Economizer
Proportional
15
0-10V
4-20 mA
0-1100
1100
50
5
Proportional
20
0-10V
4-20 mA
0- 900
900
50
6
Exponential
15
0-10V
4-20 mA
0-1100
1100
50
7
Exponential
20
0-10V
4-20 mA
0- 900
900
50
8
Health & Safety
Proportional
—
0-10V
4-20 mA
0-9999
5000
500
9
Parking/Air Intakes/
Loading Docks
Proportional
—
0-10V
4-20 mA
0-2000
700
50
UNIT
549B
UNIT
VOLTAGE
HEATER
kW
UNIT
CONFIG-
URATION
REQUIRED
MINIMUM
CFM
120
208/230
42.4
Horizontal
3200
208/230
50.0
Horizontal
3200
460
50.0
Horizontal
or
Vertical
3200