3.Turn off the electrical supply to the unit.

4.Remove the front access panel with a 5/16-in. nut driver.

5.Move the selector switch on the internal gas valve to the OFF position and wait 5 minutes.

6.Move the selector switch on the internal gas valve to the ON position.

7.Replace the front access panel.

8.Turn on the electrical supply to unit.

9.Open the external manual gas shutoff valve.

10.Set the temperature selector on UI slightly above room tem- perature to start unit. The induced-draft combustion air fan will start. Main gas valve will open and main burners should ignite within 5 seconds. If the burner does not light within 5 seconds, the ignition module will go into a Retry Mode after a period of approximately 22 seconds (following the 5-second ignition period). If the burners do not light within 15 minutes of the initial call for heat, there is a lockout.

11.Set the temperature selector on UI to desired setting.

Filter Access Panel

For Accessory Filter Rack

Access Panels

A09045

Fig. 2 - Accessory Filter Rack Access Panel

Flue Hood

Burners Gas Valve

A09043

Fig. 3 - Gas Heating/Electric Cooling Unit with Access Panel Removed (Standard unit shown. Actual appearance is shown in Fig. 2.)

!WARNING

FIRE AND EXPLOSION HAZARD

Failure to follow this warning could result in personal injury, death, and/or property damage.

1.If the main burners fail to light, or the blower fails to start, shut down gas heating section and call your dealer for service.

2.Never attempt to manually light the main burners on unit with a match, lighter, or any other flame. If the electric sparking device fails to light the main burners, refer to the following shutdown procedures, then call your dealer as soon as possible.

To Shut-off Unit Gas Heat:

!WARNING

FIRE, EXPLOSION, ELECTRICAL SHOCK HAZARD

Failure to follow this warning could result in personal injury, death, and/or property damage.

Do not turn off the electrical power to unit without first turning off the gas supply.

Note:If the unit is being shut down because of a malfunction, call your dealer as soon as possible.

Should overheating occur or the gas supply fail to shut off, shut off the external manual gas valve to the unit before shutting off the elec- trical supply. Do not use this unit if any part has been under water. Immediately call a qualified service technician to inspect the unit and to replace any part of the control system and any gas control which has been under water.

Refer to Fig. 5 while proceeding with the following steps.

1.Set the temperature selector on UI to lowest temperature set- ting and set system SWITCH to OFF.

2.Close the external manual shutoff valve.

3.Turn off the electrical power supply to the unit.

4.Remove the front access panel.

5.Move the selector switch on the internal gas valve to the OFF position.

6.Replace the front access panel.

To Start Unit Electric Cooling:

Refer to Fig. 6 while proceeding with the following steps.

1.Set the temperature selector on UI to highest temperature set- ting and set system SWITCH to OFF.

2.Close the external manual shutoff valve.

3.Turn off the electrical power supply to the unit.

4.Remove the front access panel.

5.Move the selector switch on the internal gas valve to the OFF position.

6.Replace the front access panel

7.Restore electrical power to the unit and set system switch to COOL.

8.Set the temperature selector on UI slightly below the room temperature to start unit.

To Shut Off Unit Electric Cooling:

Refer to Fig. 7 while proceeding with the following steps.

1.Set the temperature selector on UI to highest temperature set- ting and set system SWITCH to OFF.

2.Close the external manual shutoff valve.

3

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Carrier 48XT-A manual To Shut-off Unit Gas Heat, To Start Unit Electric Cooling, To Shut Off Unit Electric Cooling
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48XT-A specifications

The Carrier 48XT-A is a highly regarded commercial rooftop unit, designed to provide efficient heating, ventilation, and air conditioning (HVAC) solutions for various applications. Building on decades of innovation, this model embodies Carrier's commitment to energy efficiency, reliability, and smart technologies.

A standout feature of the Carrier 48XT-A is its compact design, making it ideal for installations where space is limited. This unit's lightweight construction allows for easier handling and installation, minimizing disruption during setup. The 48XT-A is suitable for a wide range of commercial applications, including retail spaces, offices, and warehouses.

One of the key technologies incorporated in the Carrier 48XT-A is its advanced scroll compressor, which enhances energy efficiency and reduces operational costs. This compressor operates quietly and provides stable cooling and heating performance. The unit also features a high-efficiency fan design that optimizes airflow across the coils, greatly improving the overall performance.

Another notable characteristic of the Carrier 48XT-A is its comprehensive control options. The unit is equipped with a state-of-the-art microprocessor-based control system that allows for precise temperature regulation and integrates seamlessly with building automation systems. This control capability not only enhances comfort levels but also promotes energy savings and operational efficiency.

The Carrier 48XT-A provides a range of cooling capacities, enabling flexibility to meet varying load requirements. The unit is designed to accommodate different airflow needs and is compatible with both horizontal and vertical duct configurations. This versatility ensures that it can be tailored to specific installation needs, enhancing its adaptability across different environments.

Furthermore, the construction of the Carrier 48XT-A includes durable materials that resist corrosion, ensuring longevity and reliability even in harsh operating conditions. The unit's ease of maintenance is another advantage, featuring accessible components that facilitate routine service checks.

In summary, the Carrier 48XT-A is a powerful solution for commercial HVAC needs, featuring advanced technologies, energy-efficient designs, and user-friendly controls. Its durability and adaptability make it a top choice for businesses looking to enhance comfort while managing their energy consumption effectively. The combination of innovative features and reliable performance positions the Carrier 48XT-A as a trusted solution in the commercial HVAC marketplace.
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