10.System Controls: To ensure that no catastrophic system failures occur, verify that system controls are functioning and that the sequencing is correct.

11.Freeze Protection for Water System: Verify that freeze protection is provided for the building loop water system when outdoor design conditions require it. Inadequate freeze protection can lead to expensive tower and system piping repairs.

12.System Water Loop: Verify that all air is bled from the system. Air in the system impedes unit operation and causes corrosion in the system piping.

13.Unit Filters: To avoid system damage, check that the unit filter is clean.

14.Unit Fans: Manually rotate fans to assure free rotation. Ensure that fans are properly secured to the fan shaft. Do not oil fan motors on start-up since they are lubricated at the factory.

15.System Control Center: Examine the system control and alarm panel for proper installation and operation to ensure control of the temperature set-points for operation of the system’s heat rejector and boiler (when used).

16.Miscellaneous: Note any questionable aspects of the installation.

17.Air Coil: To obtain maximum performance, the air coil should be cleaned before starting the unit. A ten percent solution of dishwasher detergent and water is recom- mended for both sides of the coil. Rinse thoroughly with water.

FIELD SELECTABLE INPUTS

Jumpers and DIP (dual in-line package) switches on the control board are used to customize unit operation and can be configured in the field.

IMPORTANT: Jumpers and DIP switches should only be clipped when power to control board has been turned off.

C Control Jumper Settings (See Fig. 4)

WATER COIL FREEZE PROTECTION (FP1) LIMIT SETTING — Select jumper 3, (JW3-FP1 Low Temp) to choose FP1 limit of 10 F or 30 F. To select 30 F as the limit, DO NOT clip the jumper. To select 10 F as the limit, clip the jumper.

AIR COIL FREEZE PROTECTION (FP2) LIMIT SET- TING — Select jumper 2 (JW2-FP2 Low Temp) to choose FP2 limit of 10 F or 30 F. To select 30 F as the limit, DO NOT clip the jumper. To select 10 F as the limit, clip the jumper.

ALARM RELAY SETTING — Select jumper 1 (JW1-AL2 Dry) for connecting alarm relay terminal (AL2) to 24 vac (R) or to remain as a dry contact (no connection). To connect AL2 to R, do not clip the jumper. To set as dry contact, clip the jumper.

C Control DIP Switches — The C Control has 1 DIP switch block with two switches. See Fig. 4.

PERFORMANCE MONITOR (PM) — DIP switch 1 will enable or disable this feature. To enable the PM, set the switch to ON. To disable the PM, set the switch to OFF.

STAGE 2 — DIP switch 2 will enable or disable compressor delay. Set DIP switch to OFF for stage 2 in which the compres- sor will have a 3-second delay before energizing.

NOTE: The alarm relay will not cycle during Test mode if switch is set to OFF, stage 2.

D Control Jumper Settings

WATER COIL FREEZE PROTECTION (FP1) LIMIT SETTING — Select jumper 3, (JW3-FP1 Low Temp) to choose FP1 limit of 10 F or 30 F. To select 30 F as the limit, DO NOT clip the jumper. To select 10 F as the limit, clip the jumper.

AIR COIL FREEZE PROTECTION (FP2) LIMIT SET- TING — Select jumper 2 (JW2-FP2 Low Temp) to choose FP2 limit of 10 F or 30 F. To select 30 F as the limit, DO NOT clip the jumper. To select 10 F as the limit (for anti-freeze sys- tems), clip the jumper.

ALARM RELAY SETTING — Select jumper 4 (JW4-AL2 Dry) for connecting alarm relay terminal (AL2) to 24 vac (R) or to remain as a dry contact (no connection). To connect AL2 to R, do not clip the jumper. To set as dry contact, clip the jumper.

LOW PRESSURE SETTING — The D Control can be con- figured for Low Pressure Setting (LP). Select jumper 1 (JW1- LP Norm Open) for choosing between low pressure input normally opened or closed. To configure for normally closed operation, do not clip the jumper. To configure for normally open operation, clip the jumper.

D Control DIP Switches — The D Control has 2 DIP switch blocks. Each DIP switch block has 8 switches and is labeled either S1 or S2 on the circuit board.

DIP SWITCH BLOCK 1 (S1) — This set of switches offers the following options for D Control configuration:

Performance Monitor (PM) — Set switch 1 to enable or dis- able performance monitor. To enable the PM, set the switch to ON. To disable the PM, set the switch to OFF.

Compressor Relay Staging Operation — Switch 2 will en- able or disable compressor relay staging operation. The com- pressor relay can be set to turn on with stage 1 or stage 2 call from the thermostat. This setting is used with dual stage units (units with 2 compressors and 2 D controls) or in master/slave applications. In master/slave applications, each compressor and fan will stage according to its switch 2 setting. If switch is set to stage 2, the compressor will have a 3-second delay before ener- gizing during stage 2 demand.

NOTE: If DIP switch is set for stage 2, the alarm relay will not cycle during Test mode.

Heating/Cooling Thermostat Type — Switch 3 provides selec- tion of thermostat type. Heat pump or heat/cool thermostats can be selected. Select OFF for heat/cool thermostats. When in heat/cool mode, Y1 is used for cooling stage 1, Y2 is used for cooling stage 2, W1 is used for heating stage 1 and O/W2 is used for heating stage 2. Select ON for heat pump applications. In heat pump mode, Y1 used is for compressor stage 1, Y2 is used for compressor stage 2, W1 is used for heating stage 3 or emergency heat, and O/W2 is used for RV (heating or cooling) depending upon switch 4 setting.

O/B Thermostat Type — Switch 4 provides selection for heat pump O/B thermostats. O is cooling output. B is heating out- put. Select ON for heat pumps with O output. Select OFF for heat pumps with B output.

Dehumidification Fan Mode (Not used on 50RTG) — Switch 5 provides selection of normal or dehumidification fan mode. Select OFF for dehumidification mode. The fan speed relay will remain OFF during cooling stage 2. Select ON for normal mode. The fan speed relay will turn on during cooling stage 2 in normal mode.

Switch 6 — Not used.

Boilerless Operation — Switch 7 provides selection of boiler- less operation and works in conjunction with switch 8. In boilerless operation mode, only the compressor is used for heating when FP1 is above the boilerless changeover tempera- ture set by switch 8 below. Select ON for normal operation or select OFF for boilerless operation.

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Carrier 50RTG specifications Field Selectable Inputs, Control Jumper Settings See Fig
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50RTG specifications

The Carrier 50RTG represents a significant advancement in the field of rooftop air conditioning systems, combining performance, efficiency, and reliability for commercial applications. Designed to meet the rigorous demands of today’s buildings, the 50RTG series is ideally suited for a variety of environments, including retail, office spaces, and industrial facilities.

One of the standout features of the Carrier 50RTG is its energy efficiency. Utilizing the latest in compressor technology, these units achieve high Seasonal Energy Efficiency Ratios (SEER) and Energy Efficiency Ratios (EER), which translates to lower energy costs for users. This efficiency is further enhanced by the incorporation of environmentally friendly refrigerants that comply with current regulations, reducing the overall carbon footprint of the unit.

Another notable characteristic of the 50RTG series is its modular design. The unit can be tailored to specific requirements, making it versatile for different installation scenarios. This modularity not only simplifies maintenance and repair operations but also allows for easy upgrades as technologies evolve or as space demands change.

The advanced control system in the 50RTG is another key technology that sets it apart from competing products. Intuitive user interfaces and smart controls enable precise temperature regulation and improved energy management. These controls often include features such as variable speed fans and integrated economizers, which optimize the system's performance in real-time based on current load requirements.

Durability is also a hallmark of the Carrier 50RTG. Constructed with robust materials and designed to withstand harsh weather conditions, these units provide dependable operation year-round. The corrosion-resistant finish and weather-tight construction ensure that the systems maintain their performance levels and aesthetic appeal over time.

Additionally, the 50RTG series is designed with a focus on low noise operation. With quieter components and advanced noise control technology, these units are ideal for noise-sensitive environments, ensuring that occupants can work, live, or shop in comfort without disruptive background noise.

In summary, the Carrier 50RTG series exemplifies the perfect combination of energy efficiency, advanced technology, customization potential, durability, and low noise operation, making it a top choice for commercial heating and cooling needs. Its innovative features and reliable performance solidify its status as a leader in rooftop HVAC solutions, catering to the evolving requirements of modern buildings.
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