Carrier Residential Air Conditioners and Heat Pumps Application Manualline

Also see for 24ANB124: Installation instructions

Carrier Residential Air Conditioners and Heat Pumps Application Manualline Manual pdf 23 page image

23REFRIGERATION SYSTEMRefrigerantUNIT OPERATION AND SAFETY HAZARDFailure to follow this warning could result in personal injuryor equipment damage.Puronr refrigerant which has higher pressures than R--22 andother refrigerants. No other refrigerant may be used in thissystem. Gauge set, hoses, and recovery system must bedesigned to handle Puronr. If you are unsure consult theequipment manufacturer.! WARNINGUNIT DAMAGE HAZARDFailure to follow this caution may result in equipmentdamage or improper operation.The compressor in a Puronr system uses a polyol ester(POE) oil. This oil is extremely hygroscopic, meaning itabsorbs water readily. POE oils can absorb 15 times as muchwater as other oils designed for HCFC and CFC refrigerants.Take all necessary precautions to avoid exposure of the oil tothe atmosphere.CAUTION!In an air conditioning and heat pump system, refrigerant transfersheat from one replace to another. The condenser is the outdoor coilin the cooling mode and the evaporator is the indoor coil.In a heat pump, the condenser is the indoor coil in the heatingmode and the evaporator is the outdoor coil.In the typical air conditioning mode, compressed hot gas leaves thecompressor and enters the condensing coil. As gas passes throughthe condenser coil, it rejects heat and condenses into liquid. Theliquid leaves condensing unit through liquid line and entersmetering device at evaporator coil. As it passes through meteringdevice, it becomes a gas--liquid mixture. As it passes throughindoor coil, it absorbs heat and the refrigerant moves to thecompressor and is again compressed to hot gas, and cycle repeats.Servicing Systems on Roofs With SyntheticMaterialsPOE (polyol ester) compressor lubricants are known to cause longterm damage to some synthetic roofing materials. Exposure, even ifimmediately cleaned up, may cause embrittlement (leading tocracking) to occur in one year or more. When performing anyservice which may risk exposure of compressor oil to the roof, takeappropriate precautions to protect roofing. Procedures which riskoil leakage include but are not limited to compressor replacement,repairing refrigerants leaks, replacing refrigerant components suchas filter drier, pressure switch, metering device, coil, accumulator,or reversing valve.Synthetic Roof Precautionary Procedure1. Cover extended roof working area with an impermeablepolyethylene (plastic) drop cloth or tarp. Cover anapproximate 10 x 10 ft area.2. Cover area in front of the unit service panel with a terrycloth shop towel to absorb lubricant spills and preventrun--offs, and protect drop cloth from tears caused by toolsor components.3. Place terry cloth shop towel inside unit immediately undercomponent(s) to be serviced and prevent lubricant run--offsthrough the louvered openings in the base pan.4. Perform required service.5. Remove and dispose of any oil contaminated material perlocal codes.BrazingThis section on brazing is not intended to teach a technician how tobraze. There are books and classes which teach and refine brazingtechniques. The basic points below are listed only as a reminder.Definition: The joining and sealing of metals using a nonferrousmetal having a melting point over 800_F/426.6_C.Flux: A cleaning solution applied to tubing or wire before it isbrazed. Flux improves the strength of the brazed connection.When brazing is required in the refrigeration system, certain basicsshould be remembered. The following are a few of the basic rules.1. Clean joints make the best joints. To clean:⎯ Remove all oxidation from surfaces to a shinyfinish before brazing.⎯ Remove all flux residue with brush and water whilematerial is still hot.2. Silver brazing alloy is used on copper--to--brass,copper--to--steel, or copper--to--copper. Flux is requiredwhen using silver brazing alloy. Do not use low temperaturesolder.3. Fluxes should be used carefully. Avoid excessiveapplication and do not allow fluxes to enter into the system.4. Brazing temperature of copper is proper when it is heated toa minimum temperature of 800_F and it is a dull red colorin appearance.Service Valves and PumpdownPERSONAL INJURY AND UNIT DAMAGE HAZARDFailure to follow this warning could result in personal injuryor equipment damage.Never attempt to make repairs to existing service valves. Unitoperates under high pressure. Damaged seats and o--ringsshould not be replaced. Replacement of entire service valve isrequired. Service valve must be replaced by properly trainedservice technician.! WARNINGService valves provide a means for holding original factory chargein outdoor unit prior to hookup to indoor coil. They also containgauge ports for measuring system pressures and provide shutoffconvenience for certain types of repairs. (See Fig. 15.)Front--seating service valves are used in outdoor residentialequipment. This valve has a service port that contains a Schraderfitting. The service port is always pressurized after the valve ismoved off the front--seat position.The service valves used in the outdoor units come from the factoryfront--seated. This means that the refrigerant charge is isolated fromthe line--set connection ports. All heat pumps are shipped with anadapter stub tube. This tube must be installed on the liquid servicevalve. After connecting the stub tube to the liquid service valve ofa heat pump, the valves are ready for brazing. The interconnectingtubing (line set) can be brazed to the service valves using industryaccepted methods and materials. Consult local codes.