Bryant 559B - Manual (Page 11)

TABLE III
SIZE UNIT CFM*
024 600
030 750
036 900
042 1050
048 1200
' *Minimum unit cfm for safe
heater operation.
delay relay provides a time delay between the heater
elements coming on or shutting off. A relay malfunction
will prevent the heaters from being energized or prevent the
heaters from being deenergized. Replace the time-delay
relay if a malfunction occurs.
C. Safety Fan Relay (14.9- through 25-KW heaters)
The safety fan relay ensures the operation of the evaporator
fan while the sequenced heater elements are energized. A
malfunction will cause excess heat problems; the fan motor
will not start or will not shut off. Replace the safety fan
relay if a malfunction occurs.
THERMOSTAT a SUBBASE
P/N34427D03O
JUMPER
THERMOSTAT
CONNECTIONS
*N0TE; W2 CONNECTION
FOR l5-a20-KW
HEATERS ONLY
COLOR-CODED LEADS
(FROM UNIT)
LOCATED INSIDE
JUNCTION BOX
Because of the numerous combinations of components that
a heating control circuit may contain, it is necessary to
measure the load in amperes, so that the thermostat heat
anticipator (s) can be set properly after the installation is
completed. A hook-around ammeter is used to measure the
heating control circuit load in this procedure.
Figure 7 shows the proper use of a hook-around ammeter to
determine the load. This illustration shows the circuit with
five turns around the jaws of the ammeter. Five turns
should be used to obtain an accurate reading.
To obtain correct heat anticipator setting, divide the am­
meter reading by the number of turns around the jaws of
the ammeter.
V. DETERMINING HEAT ANTICIPATOR SETTING
Example: 3.5 amperes 0.7 amperes setting
5 turns around jaws
Procedure for two-stage heating units:
1. Disconnect lead from thermostat terminal W1 and
make five turns around ammeter jaws. See Figure 7.
2. Disconnect lead from thermostat terminal Rh and
connect to W1 as shown in Figure 7.
3. Obtain ammeter reading for calculating first-stage
heat anticipator setting.
4. Reconnect W1 lead and disconnect W2 lead from
thermostat.
5. Follow same procedure used above to obtain ammeter
reading for calculating second-stage heat anticipator
setting.
6. Reconnect W2 and Rh leads to thermostat terminals.
NOTE: The procedure for single-stage heating units is the
same, except the leads from thermostat terminals W and 4-
R are connected together.
NOTE: For accurate load calculations, the ammeter
readings should be taken at the thermostat as shown in
Figure 7. The thermostat hookup leads must be in the cir­
cuit when taking these readings.
BRYANT
THERMOSTAT
P/N 34427D54 8
SUBBASE
P/N 34427D66
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Figure 8—Cooling and Single-Stage Heating
Thermostat Connections
Figure 9—Cooling and Two-Stage Heating
Thermostat Connections
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