Carrier 48AJ installation instructions Field Modifications, Pressure Transducer Locations

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building, route the high tap to atmosphere and the low tap to building air.

Step 12 — Install All Accessories — After all the factory-installed options have been adjusted, install all field- installed accessories. Refer to the accessory installation instruc- tions included with each accessory.

The 48A Series units have a large number of factory- installed options which were previously available only as accessories. Some of the available options can also be installed in the field if needed. In most cases the units have been pre-wired so that the accessories can be easily installed. Instructions are shipped with each accessory. Configuration of the controls for these accessories as well as the factory-installed options can be found in the Controls, Start-Up, Operation, Service and Troubleshooting Book. The following is a list of some of the common accessories:

Thermostats and space temperature sensors

LP (liquid propane) conversion kit

Accessory barometric relief damper

Accessory power exhaust

Non-modulating to modulating power exhaust

Condenser coil hail guards

Outdoor humidity sensor (used for economizer enthalpy changeover)

Return air humidity sensors (used for economizer differential enthalpy changeover)

Return air smoke detector

Controls expansion module (used for interface to build- ing management systems, not typically needed on system with the Carrier Comfort Network® [CCN] sys- tem)

Plugged filter sensor

Motormaster® V low ambient head pressure control

IMPORTANT: Carrier recommends the installation of field-fabricated wind baffles on all vertically oriented condenser coils when operating in environments with prevailing winds of more than 5 MPH and where tem- peratures drop below 32 F. See the Motormaster accessory installation guide for instructions.

Step 13 — Field Modifications

DUCTWORK

Bottom Return Units (48AJ and AK) Field-Modified for Side Return — The 48AJ and AK units with bottom return air connections may be field-modified to accommodate side return air connections.

IMPORTANT: The following section is a guideline and not a comprehensive procedure to field modify the units. The installing contractor must provide some design initiative. Field-conversion is complex and is not recommended. Units with electric heat must not be converted because of potential heating mode operating problems.

Conversion to horizontal return requires that the bottom return openings of the unit must be sealed with airtight panels

capable of supporting the weight of a person. The return ductwork connection locations on the side of the unit are higher than normal (31-in. high). Unit-mounted power exhaust or barometric relief cannot be used because of return air ductwork will cover the power exhaust or barometric relief installation locations. Power exhaust or barometric relief may be installed in the return air ductwork.

To convert the unit, perform the following:

1.Seal the bottom return openings of the unit with airtight panels capable of supporting the weight of a person.

2.Remove the panels located below the economizer outdoor-air dampers. These openings will be used for the return-air ductwork. There are 2 panels on 48AJ,AK020- 050 units. There are 3 panels on 48AJ,AK051 and 060 and units. These openings are normally used for power exhaust or barometric relief.

3.Run the return air ductwork up to the openings. One single duct is recommended to connect to the unit over the return air openings. See Fig. 34. The return duct must incorporate a minimum 3/4-in. flange for connection to the unit cabinet. The unit does not have duct flanges for this conversion.

Side Supply and Return Units (48AW,AY) with Field- Installed Power Exhaust in Return Duct — Space must be available in the return duct to mount the power exhaust fan (gravity relief) modules. Dimensions and suggested locations are shown in Fig. 34. These instructions are a guideline and not a comprehensive procedure. The design contractor must pro- vide some design initiative.

The wiring harness that is provided with the power exhaust accessory is not long enough for the fan modules to be mount- ed in the return air duct. Field-supplied wiring must be spliced into the harness. Use a junction box at each splice. The wiring may be run in the return duct, or externally in conduit. A ser- vice access panel will be needed near each power exhaust fan.

AUXILIARY

PRESSURE TRANSDUCERS

a48-6976

CONTROL BOX

(INSIDE OF PANEL)

 

Fig. 33 — Pressure Transducer Locations

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Contents Installation Instructions Instructions on Make Unit Duct ConnectionsRoof Curb 48AJ,AK020-035 Units Roof Curb 48AJ,AK036-050 Units Roof Curb 48AJ,AK051 and 060 Units A48-8235 Base Unit Dimensions 48AJ,AK020-035A48-8236 Base Unit Dimensions 48AJ,AK036-050Base Unit Dimensions 48AJ,AK051 A48-8380 Base Unit Dimensions 48AW,AY020-035Base Unit Dimensions 48AW,AY036-050 A48-8240 Base Unit Dimensions 48AW,AY051A50-8102 Center of Gravity and Weights 48AJ,AK,AW,AY051,060Compressor Physical Data 48AJ,AK,AW,AY Units035 036 040 041 Nominal Capacity tons 050 051 060 Nominal Capacity tons A48-8246 Rigging InformationConstant Volume Fan Motor Weights Unit Operating WeightsOption and Accessory Weights Air Distribution Thru-the-Bottom Evaporator Fan Motor DataA48-3714 Install Flue HoodA48-3712 A48-3823A48-2524 Make Electrical Connections48A Series Staged Gas Control Unit Voltage 48A Min Max 46.2 203.6 225 Unbalanced 3-Phase Supply Voltage FLA MCA Electrical Data 48AJ,AK,AW,AY Units with Convenience Outlet030 040 Hacr Size Stage A48-6854 A48-8243Color Code Recommendations CCN Connection Approved Shield CableAdding Seal Strip to Top of Hood Sides Make Outdoor-Air Inlet AdjustmentsA48-8499 48-110448-1105 A48-4328A48-3808 Route VAV Static Pressure SensorsA48-8244 Pressure Transducer Locations Field ModificationsA48-8245 Side Return Air Conversion
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48AJ 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.