Crankcase Heater Ð Each compressor has a crankcase heater to prevent absorption of liquid refrigerant by oil in the crank- case when the compressor is idle. Since power for the crank- case heaters is drawn from the unit incoming power, main unit power must be on for the heaters to be energized.

IMPORTANT: After a prolonged shutdown or serv- ice job, energize the crankcase heaters for 24 hours before starting the compressors.

EVAPORATOR FAN MOTOR PROTECTION Ð A manual reset, calibrated trip, magnetic circuit breaker protects against overcurrent. Do not bypass connections or increase the size of the breaker to correct trouble. Determine the cause and correct it before resetting the breaker. If the evaporator-fan motor is replaced with a different horsepower motor, resiz- ing of the circuit breaker is required. Contact Carrier Application Engineering.

CONDENSER-FAN MOTOR PROTECTION Ð Each condenser-fan motor is internally protected against overtemperature.

HIGH- AND LOW-PRESSURE SWITCHES Ð If either switch trips, or if the compressor overtemperature switch ac- tivates, that refrigerant circuit will be automatically stopped. See Compressor Lockout Logic section on this page.

FREEZE PROTECTION THERMOSTAT (FPT) Ð Freeze protection thermostats are located on the evaporator coil for each circuit. One is located at the top and bottom of each circuit. 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.

Relief Devices Ð All units have relief devices to pro- tect against damage from excessive pressures (i.e., ®re). These devices are installed on the suction line, liquid line, and on the compressor.

Power Circuit Ð A typical power wiring schematic is shown in Fig. 56.

Control Circuit, 115-V Ð This control circuit is pro- tected against overcurrent by a 5.0 amp circuit breaker (CB3). Breaker can be reset. If it trips, determine cause of trouble before resetting. A typical 115-v control wiring schematic is shown in Fig. 57 and 58.

Control Circuit, 24-V Ð This control circuit is pro- tected against overcurrent by a 3.2 amp circuit breaker (CB4). Breaker can be reset. If it trips, determine cause of trouble before resetting. A typical 24-v control wiring schematic is shown in Fig. 59 and 60.

Compressor Lockout Logic Ð If any of the safe- ties trip, the circuit will automatically reset (providing the safety has reset) and restart the compressor in 15 minutes. If any of the safeties trip 3 times within a 90-minute period, then the circuit will be locked out and will require manual resetting by turning off either the unit disconnect or the con- trol circuit breaker, or opening the thermostat.

Replacement Parts Ð A complete list of replacement parts may be obtained from any Carrier distributor upon request.

Fig. 54 Ð Gas Valve

Fig. 55 Ð Main Burner Removal

49

Page 48 Page 50
Page 49
Image 49
Carrier EW, 48EJ, EK, EY024-048 installation instructions Gas Valve
Page 48 Page 50

EW, EY024-048, EK, 48EJ specifications

The Carrier 48EJ, 48AW, 48EK, 48AJ, and 48EY024-068 are cutting-edge rooftop air conditioning units designed for commercial applications. These models are renowned for their reliability, energy efficiency, and innovative technologies aimed at providing optimal indoor comfort.

One of the standout features of these units is their advanced cooling and heating capabilities. They employ a multi-stage compressor system that allows for precise temperature control, accommodating various load requirements. This flexibility is particularly beneficial in commercial settings where the cooling load can fluctuate throughout the day.

Energy efficiency is paramount in today’s environmental landscape, and Carrier has ensured that these models meet stringent efficiency standards. They incorporate high-efficiency scroll compressors, which significantly reduce energy consumption while delivering powerful performance. The units are also equipped with variable speed fans that adjust airflow based on demand, further optimizing energy use.

In terms of construction, these rooftop units feature a robust design that enhances durability and longevity. The cabinet is constructed to withstand harsh weather conditions, ensuring reliable performance year-round. Additionally, the units are equipped with corrosion-resistant coatings, particularly useful in coastal environments where salt exposure can be a concern.

The Carrier 48EJ, 48AW, 48EK, 48AJ, and 48EY models utilize advanced controls and connectivity features, allowing for easy integration into building management systems. This connectivity enables remote monitoring and control, facilitating quick response to changing conditions and simplifying maintenance tasks.

Noise reduction is another key characteristic of these models. They are designed with sound-absorbing insulation and low-noise fan blades to ensure quiet operation, making them suitable for noise-sensitive environments such as schools and hospitals.

These units are also available with various options for air filtration and dehumidification. The use of high-efficiency air filters enhances indoor air quality by trapping dust, pollen, and other airborne particles. Enhanced dehumidification capabilities ensure that spaces remain comfortable even in humid conditions.

In conclusion, the Carrier 48EJ, 48AW, 48EK, 48AJ, and 48EY024-068 rooftop units are engineered to offer exceptional performance, energy efficiency, and durability. With their advanced technologies and user-friendly features, they stand out as reliable solutions for meeting diverse commercial cooling and heating needs, making them a popular choice for many businesses.
Top Page Image Contents