Step 8 — Pressure Switches

Pressure switches are protective devices wired into control circuit (low voltage). They shut off compressor if abnormally high or low pressures are present in the refrigeration circuit. These pressure switches are specifically designed to operate with Puron (R-410A) systems. R-22 pressure switches must not be used as replacements for the Puron (R-410A) system.

Step 9 — Loss of Charge Switch

This switch is located on the liquid line and protects against low suction pressures caused by such events as loss of charge, low airflow across indoor coil, dirty filters, etc. It opens on a pressure drop at about 20 psig. If system pressure is above this, switch should be closed. To check switch:

1.Turn off all power to unit.

2.Disconnect leads on switch.

3.Apply ohm meter leads across switch. You should have continuity on a good switch.

NOTE: Because these switches are attached to refrigeration system under pressure, it is not advisable to remove this device for troubleshooting unless you are reasonably certain that a problem exists. If switch must be removed, remove and recover all system charge so that pressure gauges read 0 psig. Never open system without breaking vacuum with dry nitrogen.

Step 10 — High-Pressure Switch

The high-pressure switch is located in the discharge line and protects against excessive condenser coil pressure. It opens at 650 psig.

High pressure may be caused by a dirty outdoor coil, failed fan motor, or outdoor air recirculation.

To check switch:

1.Turn off all power to unit.

2.Disconnect leads on switch.

3.Apply ohm meter leads across switch. You should have continuity on a good switch.

Step 11 — Copeland Scroll Compressor (Puron Refrigerant)

The compressor used in this product is specifically designed to operate with Puron (R-410A) refrigerant and cannot be interchanged.

!WARNING

EXPLOSION HAZARD

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

Wear safety glasses and gloves when handling refrigerants. Keep torches and other ignition sources away from refrigerant and oils.

The scroll compressor pumps refrigerant throughout the system by the interaction of a stationary and an orbiting scroll. The scroll compressor has no dynamic suction or discharge valves, and it is more tolerant of stresses caused by debris, liquid slugging, and flooded starts. The compressor is equipped with an internal pressure relief port. The pressure relief port is a safety device, designed to protect against extreme high pressure. The relief port has an operating range between 550 and 625 psig differential pressure.

Step 12 — Refrigerant System

This step covers the refrigerant system of the 50VT-A, including the compressor oil needed, servicing systems on roofs containing synthetic materials, the filter drier and refrigerant charging.

Refrigerant

!WARNING

PROPERTY HAZARD, PERSONAL INJURY OR ENVIRONMENTAL HAZARD

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

This system uses Puron (R-410A) refrigerant which has higher operating pressures than R-22 and other refrigerants. No other refrigerant may be used in this system. Gauge set, hoses, and recovery system must be designed to handle Puron. If you are unsure consult the equipment manufacturer.

Compressor Oil

The Copeland scroll compressor uses 3MAF POE oil. If additional oil is needed, use Uniqema RL32-3MAF. If this oil is not available, use Copeland Ultra 32 CC or Mobil Arctic EAL22 CC. This oil is extremely hygroscopic, meaning it absorbs water readily. POE oils can absorb 15 times as much water as other oils designed to HCFC and CFC refrigerants. Take all necessary precautions to avoid exposure of the oil to the atmosphere.

Servicing Systems on Roofs with Synthetic Materials

POE (polyolester) compressor lubricants are known to cause long term damage to some synthetic roofing materials. Exposure, even if immediately cleaned up, may cause embrittlement (leading to cracking) to occur in one year or more. When performing any service that may risk exposure of compressor oil to the roof, take appropriate precautions to protect roofing. Procedures which risk oil leakage include, but are not limited to, compressor replacement, repairing refrigerant leaks, replacing refrigerant components such as filter drier, pressure switch, metering device, coil, accumulator, or reversing valve.

Synthetic Roof Precautionary Procedure

1.Cover extended roof working area with an impermeable polyethylene (plastic) drip cloth or tarp. Cover an approximate 10x10 ft (3x3 m) area.

2.Cover area in front of the unit service panel with a terry cloth shop towel to absorb lubricant spills and prevent run-offs, and protect drop cloth from tears caused by tools or components.

3.Place terry cloth shop towel inside unit immediately under component(s) to be serviced and prevent lubricant run-offs through the louvered openings in the unit base.

4.Perform required service.

5.Remove and dispose of any oil contaminated material per local codes.

Liquid Line Filter Drier

The biflow filter drier is specifically designed to operate with Puron. Use only factory-authorized components. Filter drier must be replaced whenever the refrigerant system is opened. When removing a filter drier, use a tubing cutter to cut the drier from the system. Do not unsweat a filter drier from the system. Heat from unsweating will release moisture and contaminants from drier into system.

50VT-- A

27

Page 27
Image 27
Carrier 50VT-A installation instructions Pressure Switches, Loss of Charge Switch, High-Pressure Switch, Refrigerant System

50VT-A specifications

Carrier’s 50VT-A and 50EZ-A series exemplify cutting-edge advancements in heating, ventilation, and air conditioning (HVAC) technology. These products are engineered to meet diverse climate control needs in residential and commercial applications while ensuring operational efficiency and superior indoor air quality.

The Carrier 50VT-A series stands out with its variable-speed technology, which allows for precise temperature control by adjusting the cooling or heating output based on current demand. This capability not only optimizes energy consumption but also enhances comfort by eliminating temperature swings. The 50VT-A units are equipped with hybrid heat technology, which enables seamless integration with alternative heating sources, providing flexibility in energy use.

On the other hand, the Carrier 50EZ-A offers a unique solution for those seeking efficient and reliable climate control in a more compact design. This series incorporates advanced inverter technology, which continuously adjusts the compressor speed, ensuring that the system operates at the utmost efficiency regardless of environmental conditions. The result is significant energy savings and quieter operation compared to traditional units.

Both series feature intelligent refrigerant management, utilizing R-410A refrigerant, which is environmentally friendly and designed to reduce greenhouse gas emissions. The systems are engineered with robust insulation and sound-dampening materials, minimizing noise levels for a peaceful indoor environment.

In addition to their impressive technical specifications, the Carrier 50VT-A and 50EZ-A units come equipped with smart controls, allowing users to monitor and adjust settings remotely through mobile applications. This connectivity feature empowers homeowners and businesses to manage energy consumption, set schedules, and receive maintenance alerts, ensuring optimal performance at all times.

Durability is an important characteristic of both series, as they are designed to withstand various environmental conditions. With corrosion-resistant coatings and high-grade materials, these units promise longevity and reliable performance over their operational lifespan.

In summary, Carrier’s 50VT-A and 50EZ-A series offer an innovative blend of efficiency, advanced technology, and user-friendly features. Whether for residential or commercial applications, these systems provide exceptional comfort, lower energy costs, and an environmentally conscious choice for modern HVAC solutions.