Check For Refrigerant Leaks; Unit Sequence Of Operation; 574B Sequence Of Operation; Start- -Up Heating & Make Adjustments - Bryant 574B Installation Instructions Manual

START- - UP
Step 1 — CHECK FOR REFRIGERANT LEAKS
Proceed as follows to locate and repair a refrigerant leak and to
charge the unit:
1. Locate leak and make sure that refrigerant system pressure
has been relieved and reclaimed from both high- - and
low- -pressure ports.
2. Repair leak following Refrigerant Service procedures.
NOTE: Install a filter drier whenever the system has been
opened for repair.
3. Add a small charge of R- -410A refrigerant vapor to system
and leak- -test unit.
4. Evacuate and recover refrigerant from refrigerant system if
additional leaks are not found.
5. Charge unit with
volumetriccharging cylinder or accurate scale. Refer to
unit rating plate for required charge. Be sure to add extra
refrigerant to compensate for internal volume of filter
drier.
Step 2 — UNIT SEQUENCE OF OPERATION

574B Sequence of Operation

a. CONTINUOUS FAN
(1.) Thermostat closes circuit R to G- -The Blower
runs at continuous fan airflow
b. COOLING MODE
(1.) If indoor temperature is above temperature set
point and humidity is below humidity set point,
thermostat closes circuits R to G, R to Y/Y2 and
R to O- -The unit delivers single speed cooling
airflow.
c. COOLING MODE- -DEHUMIDIFICATION
(1.) If indoor temperature is above temperature set
point and humidity is above humidity set point,
thermostat or Thermidistat closes circuits R to G,
R to Y/Y2, R to O and humidistat or Thermidistat
opens R to DH- -The unit delivers airflow which is
approximately 80 percent of the nominal cooling
airflow to increase the latent capacity of the
system.
d. COOLING MODE- -SUPER DEHUMIDIFY
OPERATION (SEE QUICK REFERENCE GUIDE)
NOTE: The indoor control used, such as a Thermidistat, must be
capable of providing Super Dehumidify operation mode and
control must be configured as outlined in its installation
instructions. Consult indoor control literature to determine if
control is capable of providing Super Dehumidify inputs and for
configuration instruction.
(1.) If the indoor temperature is below the temperature
set point and the humidity is above the humidity
set point, the Thermidistat closes circuit R to O,
opens circuits R to DH and R to G, and closes
circuit R to Y/Y2. If circuit R to G is closed
(24- -v.), the motor will deliver airflow at the full
cooling or cooling plus dehumidify mode
requested value. If circuit R to G is open (0- -v.)
for Super Dehumidify mode, the motor delivers
reduced airflow to maximize the humidity
removal of the system while minimizing over
cooling.
e. GAS HEATING MODE
(1.) Thermostat closes circuit R to W/W1- -The unit
delivers the selected gas heat airflow. The IGC
will control a 45 sec. blower "On" delay and a 45
sec. "Off" delay.
R- -410A refrigerant, using
Step 3 — START- - UP HEATING AND MAKE
ADJUSTMENTS
!
UNIT COMPONENT DAMAGE HAZARD
Failure to follow this caution may result in damage to the unit
being installed.
Complete the required procedures given in the Pre- -Start- -Up
section before starting the unit. Do not jumper any safety
devices when operating the unit.
Make sure that burner orifices are properly aligned. Unstable
operation may occur when the burner orifices in the manifold are
a
misaligned.
Follow the lighting instructions on the heating section operation
label (located inside the burner or blower access door) to start the
heating section.
NOTE: Make sure that gas supply has been purged, and that all
gas piping has been checked for leaks.
CHECK HEATING CONTROL
Start and check the unit for proper cooling control operation as
follows (see furnace lighting instructions located inside burner or
blower access panel):
1. Place room thermostat SYSTEM switch in the HEAT
position and the fan switch is placed in AUTO position.
2. Set the heating temperature control of the thermostat
above room temperature.
3. The induced- -draft motor will start.
4. After a call for heating, the main burner should light
within 5 sec. If the burners do not light, there is a 22- -sec.
delay before another 5- -sec. try. If the burners still do not
light, this sequence is repeated. If the burners do not light
within 15 minutes from the initial call for heat, there is a
lockout. To reset the control, break the 24- -v power to W.
5. The evaporator fan will turn on 45 sec. after the flame has
been established. The evaporator fan will turn off 45 sec.
after the thermostat has been satisfied.

CHECK GAS INPUT

Check gas input and manifold pressure after unit start- -up (See
Table 3). If adjustment is required proceed as follows:
S The rated gas inputs shown in Table 3 are for altitudes from
sea level to 2000 ft above sea level. These inputs are based on
natural gas with a heating value of 1050 Btu/ft
gravity, or propane gas with a heating value of 2500 Btu/ft
1.5 specific gravity.
S For elevations above 2000 ft, reduce input 4% for each 1000
ft above sea level.
S When the gas supply being used has a different heating value
or specific gravity, refer to national and local codes, or contact
your distributor to determine the required orifice size.
!
UNIT DAMAGE HAZARD
Failure to follow this caution may result in reduced unit and/or
component life.
Do Not redrill an orifice. Improper drilling (burrs,
out- -of- -round holes, etc.) can cause excessive burner noise
and misdirection of burner flame. Replace with correct sized
orifices.
15
CAUTION
3
at 0.65 specific
CAUTION
3
at