![OPERATION](/images/new-backgrounds/34008/3400837x1.webp)
OPERATION
COOLING SYSTEM
The cooling section is a complete factory package utilizing an
The compressors are hermetically sealed, internally sprung and
Compressors have inherent (internal) protection. If there is an abnormal temperature rise in a compressor, the protector will open to shut down the compressor.
PRELIMINARY OPERATION COOLING
After installation has been completed, energize the crank- case heaters for at least four hours before operating the unit. After the initial installation, the compressors should be given three false starts (energized just long enough to make a few revolutions) with
NOTE: Prior to each cooling season, the crankcase heaters must be energized at least 8 hours before system is put into operation.
COOLING SEQUENCE OF OPERATION
NO OUTDOOR AIR OPTIONS
When the room thermostat calls for
When the thermostat calls for
After the thermostat is satisfied and opens, all components will stop simultaneously. The blower motor will continue to operate if the fan switch on the room thermostat is set in the ON position.
ECONOMIZER WITH SINGLE ENTHALPY SENSOR
When the room thermostat calls for
modulate to maintain a constant supply air temperature as monitored by the discharge air sensor. If the outdoor air enthalpy is above the setpoint, Y1 energizes compressor #1, condenser fan motor #1, and condenser fan motor #2 (if the ambient temperature is above 60°F).
When the thermostat calls for
After the thermostat is satisfied and opens, all components will stop simultaneously. The blower motor will continue to operate if the fan switch on the room thermostat is set in the ON position.
ECONOMIZER WITH DUAL ENTHALPY SENSORS
The operation with the dual enthalpy sensors is identical to the single sensor except that a second enthalpy sensor is mounted in the return air. This return air sensor allows the economizer to choose between outdoor air and return air, whichever has the lowest enthalpy value, to provide maxi- mum operating efficiency.
ECONOMIZER (SINGLE OR DUAL) WITH POWER EXHAUST
This system operates as specified above with one addition. The power exhaust motor is energized whenever the econo- mizer is chosen by the enthalpy sensor for first stage cooling, Y1. As always, the R to G connection provides minimum position but does not provide power exhaust operation.
MOTORIZED OUTDOOR AIR DAMPERS
This system operation is the same as the units with no out- door air options with one exception. When the R to G circuit is complete, the motorized damper drives open to a position set by the thumbwheel on the damper motor. When the R to G circuit is opened, the damper spring returns fully closed.
CONTINUOUS BLOWER
Continuous blower operation is possible by closing the R to G circuit on the thermostat.
SAFETY CONTROLS
1.A Suction Line Freezestat to protect against low evapo- rator temperatures due to a low air flow or a low return air temperature. (Opens at 26°F + 5°F and resets at 38°F + 5°F)
2.A High Pressure Cutout Switch to protect against exces- sive discharge pressures due to a blocked condenser coil or a condenser motor failure. (Opens at 380 psig + 10 and resets at 300 psig +10)
Unitary Products | 19 |