Bryant DURAPAC 580F - Manual (Page 37)

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XII. SAFETY RELIEF
A soft solder joint at the suction service Schrader port pro-
vides pressure relief under abnormal temperature and pres-
sure conditions (i.e., fire in building).
XIII. VENTILATION (CONTINUOUS FAN)
Set fan and system selector switches at ON and OFF posi-
tions, respectively. Evaporator fan operates continuously to
provide constant air circulation. When the evaporator-fan
selector switch is turned to the OFF position, there is a
30-second delay before the fan turns off.
XIV. OPERATING SEQUENCE
A. Cooling, Units without EconoMi$er IV
When thermostat calls for cooling, terminals G and Y1 and
the compressor contactor (C) are energized. The indoor
(evaporator) fan motor (IFM), compressor, and outdoor (con-
denser) fan motor (OFM) start. The OFM runs continuously
while the unit is in cooling. When the thermostat is satisfied,
C is deenergized and the compressor and OFM shut off. After
a 30-second delay, the (IFM) shuts off. If the thermostat fan
selector switch is in the ON position, the evaporator motor
will run continuously.
B. Heating, Units without EconoMi$er IV
When the thermostat calls for heating, terminal W1 is ener-
gized. The induced-draft motor is energized and the burner
ignition sequence begins. The indoor (evaporator) fan motor
(IFM) is energized 45 seconds after a flame is ignited. When
additional heat is needed, W2 is energized and the high-fire
solenoid on the main gas valve (MGV) is energized. When
the thermostat is satisfied and W1 is deenergized, the IFM
stops after a 45-second time-off delay.
C. Cooling, Units with EconoMi$er IV
When free cooling is not available, the compressors will be
controlled by the zone thermostat. When free cooling is avail-
able, the outdoor-air damper is modulated by the
EconoMi$er IV control to provide a 50 to 55 F supply-air
temperature into the zone. As the supply-air temperature
fluctuates above 55 or below 50 F, the dampers will be modu-
lated (open or close) to bring the supply-air temperature
back within set point limits.
Integrated EconoMi$er IV operation on single-stage units
requires a 2-stage thermostat (Y1 and Y2).
For EconoMi$er IV operation, there must be a thermostat
call for the fan (G). This will move the damper to its mini-
mum position during the occupied mode.
Above 50 F supply-air temperature, the dampers will modu-
late from 100% open to the minimum open position. From
50 F to 45 F supply-air temperature, the dampers will main-
tain at the minimum open position. Below 45 F the dampers
will be completely shut. As the supply-air temperature rises,
the dampers will come back open to the minimum open posi-
tion once the supply-air temperature rises to 48 F.
If optional power exhaust is installed, as the outdoor-air
damper opens and closes, the power exhaust fans will be
energized and deenergized.
If field-installed accessory CO
2
sensors are connected to the
EconoMi$er IV control, a demand controlled ventilation
strategy will begin to operate. As the CO
2
level in the zone
increases above the CO
2
set point, the minimum position of
the damper will be increased proportionally. As the CO
2
level
decreases because of the increase in fresh air, the outdoor-air
damper will be proportionally closed. Damper position will
follow the higher demand condition from DCV mode or free
cooling mode.
On the initial power to the EconoMi$er IV control, it will take
the damper up to 2
1 /
2
minutes before it begins to position
itself. Any change in damper position will take up to 30 sec-
onds to initiate. Damper movement from full closed to full
open (or vice versa) will take between 1
1 /
2
and 2 1 /
2
minutes.
If free cooling can be used as determined from the appropri-
ate changeover command (switch, dry bulb, enthalpy curve,
differential dry bulb, or differential enthalpy), a call for cool-
ing (Y1 closes at the thermostat) will cause the control to
modulate the dampers open to maintain the supply air tem-
perature set point at 50 to 55 F.
As the supply air temperature drops below the set point range
of 50 to 55 F, the control will modulate the outdoor-air damp-
ers closed to maintain the proper supply-air temperature.
D. Heating, Units with EconoMi$er IV
When the room temperature calls for heat, the heating
controls are energized as described in the Heating, Units
Without Economizer section. When the thermostat is satis-
fied, the economizer damper moves to the minimum position.
SERVICE
I. CLEANING
Inspect unit interior at the beginning of heating and cooling
season and as operating conditions require.
A. Evaporator Coil
1. Turn unit power off and install lockout tag. Remove
evaporator coil access panel.
2. If economizer or two-position damper is installed,
remove economizer by disconnecting Molex plug and
removing mounting screws.
3. Slide filters out of unit.
4. Clean coil using a commercial coil cleaner or dish-
washer detergent in a pressurized spray canister.
Wash both sides of coil and flush with clean water.
For best results, back-flush toward return-air section
to remove foreign material. Flush condensate pan
after completion.
5. Reinstall economizer and filters.
6. Reconnect wiring.
7. Replace access panels.
B. Condenser Coil
Inspect coil monthly. Clean condenser coil annually, and as
required by location and outdoor air conditions.
One-Row Coils (Size 036)
Wash coil with commercial coil cleaner. It is not necessary to
remove top panel.
CAUTION: When servicing unit, shut off all electri-
cal power to unit and install lockout tag to avoid shock
hazard or injury from rotating parts.