Bryant 551a Heating System User Manual


 
30
E. Freeze Protection Thermostat (FPT)
An FPT is located on the top and bottom of the evaporator
coil. It detects frost build-up and turns off the compressor,
allowing the coil to clear. Once the frost has melted, the com-
pressor can be reenergized.
XII. RELIEF DEVICES
All units have relief devices to protect against damage from
excessive pressures (e.g., fire). These devices protect the high
and low side.
XIII. CONTROL CIRCUIT, 24-V
This control circuit is protected against overcurrent by a
3.2-amp circuit breaker. Breaker can be reset. If it trips,
determine cause of trouble before resetting. See Fig. 36 and
37.
XIV. REPLACEMENT PARTS
A complete list of replacement parts may be obtained from
any Bryant distributor upon request.
XV. ECONOMI$ER LEDs
The EconoMi$er control module has LEDs for diagnostic
purposes. The flash code identification is shown in Table 17.
XVI. OPTIONAL HINGED ACCESS DOORS
When the optional service package is ordered or the if the
hinged access doors option is ordered, the unit will be pro-
vided with external and internal hinged access doors to facil-
itate service.
Four external hinged access doors are provided. All external
doors are provided with 2 large
1
/
4
turn latches with folding
bail-type handles. (Compressor access doors have one latch.)
A single door is provided for filter and drive access. One door
is provided for control box access. The control box access door
is interlocked with the non-fused disconnect which must be
in the OFF position to open the door. Two doors are provided
for access to the compressor compartment.
Two internal access doors are provided inside the filter/drive
access door. The filter access door (on the left) is secured by 2
small
1
/
4
turn latches with folding bail-type handles. This
door must be opened prior to opening the drive access door.
The drive access door is shipped with 2 sheet metal screws
holding the door closed. Upon initial opening of the door,
these screws may be removed and discarded. The door is
then held shut by the filter access door, which closes over it.
LEGEND AND NOTES FOR FIG. 36 AND 37
LEGEND
AHA
Adjustable Heat Anticipator
BRK W/AT
Breaks with Amp Turns
C
Contactor, Compressor
CAP
Capacitor
CB
Circuit Breaker
CC
Cooling Compensator
CH
Crankcase Heater
CLO
Compressor Lockout
COMP
Compressor Motor
CR
Control Relay
DAT
Discharge Air Thermistor
DM
Damper Motor
DU
Dummy Terminal
EC
Enthalpy Control
EQUIP
Equipment
FL
Fuse Link
FPT
Freeze Protection Thermostat
FU
Fuse
GND
Ground
HC
Heater Contactor
HPS
High-Pressure Switch
HTR
Heater
IFC
Indoor-Fan Contactor
IFCB
Indoor-Fan Circuit Breaker
IFM
Indoor-Fan Motor
IFR
Indoor-Fan Relay
L
Light
LPS
Low-Pressure Switch
LS
Limit Switch
NEC
National Electrical Code
OAT
Outdoor-Air Thermostat
OFC
Outdoor-Fan Contactor
OFM
Outdoor-Fan Motor
OP
Overcurrent Protection
PL
Plug Assembly
PRI
Primary
QT
Quadruple Terminal
SW
Switch
TB
Terminal Block
TC
Thermostat Cooling
TH
Thermostat Heating
TRAN
Transformer
Terminal (Marked)
Terminal (Unmarked)
Terminal Block
Splice
Factory Wiring
Field Wiring
Option/Accessory Wiring
To indicate common potential
only; not to represent wiring.
NOTES:
1. Compressor and/or fan motor(s) thermally protected; 3-phase motors protected
against primary single-phasing conditions.
2. If any of the original wire furnished must be replaced, it must be replaced with type
90° C wire or its equivalent.
3. Jumpers are omitted when unit is equipped with EconoMi$er.
5. IFCB must trip amps is equal to or less than 140% FLA.
6. The CLO locks out the compressor to prevent short cycling on compressor over-
load and safety devices. Before replacing CLO, check these devices.
7. Number(s) indicates the line location of used contacts. A bracket over (2) numbers
signifies a single-pole, double-throw contact. An underlined number signifies a
normally closed contact. Plain (no line) number signifies a normally open contact.