Modern Refrigeration and Air Conditioning, 21st Edition, Online Textbook Page 822 (850 of 1632)

Copyright Goodheart-Willcox Co., Inc. 822 Air-Conditioning Systems The outdoor unit is mounted outside. This can be done in a variety of manners depending on the building and the space available. Common installations are on a concrete slab, pads, a wall-mounted bracket, a riser, or metal stand, Figure 32-37. Larger outdoor units are often mounted on a concrete slab or mounting pad, Figure 32-38. Wall brack- ets include rubber mounts to keep the vibration from the unit from transferring into the house. When installing a unit on a concrete slab or mounting pad, be sure to main- tain any required clearance under the unit. In addition, maintain all clearances around and above the outdoor unit as specified in the manufacturer’s installation guide. For heat pump systems in cold climates, the outdoor unit must be installed off the ground so it remains above any snow. If an outdoor heat pump unit is surrounded by snow, airflow through the outdoor coil will be blocked and the unit will not operate properly. The outdoor unit may include a base pan heater to defrost snow and ice. In these cases, the melted snow and ice must be able to drain away from the unit. If storms and wind generally come from the west, locating the outdoor unit on the east side of the home provides additional shielding for the unit. To install a wall-mount indoor unit, first install the wall bracket. The wall bracket is attached to two wall A C D B Fujitsu General America, Inc. RectorSeal Figure 32-37. Ductless split system outdoor units. A—Two outdoor units mounted on pads. B—Wall-mounted bracket. C—Riser mounting. D—Metal stand mounting. Fujitsu General America, Inc. Figure 32-38. Two technicians positioning an outdoor unit on a mounting pad.

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Copyright Goodheart-Willcox Co., Inc. 822 Air-Conditioning Systems The outdoor unit is mounted outside. This can be done in a variety of manners depending on the building and the space available. Common installations are on a concrete slab, pads, a wall-mounted bracket, a riser, or metal stand, Figure 32-37. Larger outdoor units are often mounted on a concrete slab or mounting pad, Figure 32-38. Wall brack- ets include rubber mounts to keep the vibration from the unit from transferring into the house. When installing a unit on a concrete slab or mounting pad, be sure to main- tain any required clearance under the unit. In addition, maintain all clearances around and above the outdoor unit as specified in the manufacturer’s installation guide. For heat pump systems in cold climates, the outdoor unit must be installed off the ground so it remains above any snow. If an outdoor heat pump unit is surrounded by snow, airflow through the outdoor coil will be blocked and the unit will not operate properly. The outdoor unit may include a base pan heater to defrost snow and ice. In these cases, the melted snow and ice must be able to drain away from the unit. If storms and wind generally come from the west, locating the outdoor unit on the east side of the home provides additional shielding for the unit. To install a wall-mount indoor unit, first install the wall bracket. The wall bracket is attached to two wall A C D B Fujitsu General America, Inc. RectorSeal Figure 32-37. Ductless split system outdoor units. A—Two outdoor units mounted on pads. B—Wall-mounted bracket. C—Riser mounting. D—Metal stand mounting. Fujitsu General America, Inc. Figure 32-38. Two technicians positioning an outdoor unit on a mounting pad.

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Copyright Goodheart-Willcox Co., Inc. Chapter 32 Residential Split Air-Conditioning Systems 821 10 the metering device for the unit. Some indoor units may have a condensate pump or a heating unit. The thermistors measure the coil temperature and air temperature. These readings are continuously communi- cated back to the control board. Based on these readings, the system can adjust EEVs and the compressor output. As an indoor unit operates, moisture condenses on the coil and flows into a condensate pan. Some units are designed to drain by gravity, and other units use a conden- sate pump. This moisture usually drains out. However, if the drain line becomes blocked or the condensate pump fails, water could overflow the pan. The overflowing water could damage walls, ceilings, flooring, and furnishings. To avoid an overflowing drain pan, many indoor units are equipped with an overflow switch. See Figure 32-35. When the overflow switch senses, it opens a switch to shut off operation to the indoor unit. With no more refrigerant moving through the refrigeration coil, water stops con- densing on the coil and draining into the pan. Some indoor units include an occupancy sensor. An occupancy sensor senses when a room is occupied and when a room is not occupied. A system with occupancy sensors can be programmed to one temperature set point for an occupied room and a different set point when the room is unoccupied. Typically, an indoor unit is controlled with a remote control, Figure 32-36. The remote control may be used to turn the unit on or off, change the temperature setting, change the fan speed, and change the direction of the sup- ply air. Note that the thermostat is located in the unit, not in the remote control. Wall-mounted thermostats are also available with most systems. A line set typically contains the refrigerant lines, elec- trical wiring, and a condensate drain. Electrical power is Overflow switch RectorSeal Figure 32-35. This overflow switch mounts to the condensate pan and turns off the indoor unit when an accumulation of condensate is sensed. supplied to the indoor unit through the line set, so a sep- arate electrical connection is not needed for the indoor units. One common component that is typically not included in ductless systems is a filter-drier. Since ductless systems do not contain a filter-drier, extra care is needed to ensure that con- taminants are not introduced into the refrigerant lines. 32.6.2 Ductless System Installation Compared to installing a central air-conditioning system, installing a ductless system is generally much easier. How- ever, with ductless systems, all installation instructions provided by the manufacturer must be followed. These instructions may vary from manufacturer to manufac- turer and even from unit to unit, so always be sure to have the correct installation guides. Indoor Unit Disconnect Some building codes and building inspectors may determine that the outdoor electrical disconnect is too far from one or more indoor units. In these cases, an electrical disconnect for the indoor unit must be installed in a location acceptable to the authority having jurisdiction. Code Alert Fujitsu General America, Inc. Figure 32-36. Ductless split systems are easily programmed using a remote control or a smartphone app using WiFi.

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Copyright Goodheart-Willcox Co., Inc. Chapter 32 Residential Split Air-Conditioning Systems 823 10 studs. Be sure to level the wall bracket. If the bracket is not level, the unit will look crooked on the wall and the con- densate drain may not function correctly. After the wall bracket is installed, drill a 3″ hole in the wall for the line set. Use the installation guide to deter- mine the hole’s location. See Figure 32-39. Many indoor units are mounted on walls, near the ceil- ing. It can be difficult to hold the unit in place while neces- sary wiring and other connections are made. Once the wall plate is secured into place, a bracket can be attached to hold the indoor unit in place, Figure 32-40. Ductless systems have minimum and maximum lengths for line sets. Line sets are also limited to a maxi- mum vertical change. Always measure and record the line set lengths and verify that the measurements fall in the acceptable range for the product. The condensate drain is generally 5/8″ flexible hose. Do not use 3/8″ clear plastic condensate tubing in a duct- less system. This smaller tubing may bend, resulting in blockages. Any condensate drain issues are major prob- lems with a ductless system because if the drain pan overflows, it will immediately cause damage in a living area. Slope condensate drain hose a minimum of 1/4″ per foot. If a gravity drain is not possible, install a condensate pump. Flared connections are used for the refrigerant line connections. (Flared connections are discussed in Chapter 8, Working with Tubing and Piping.) Poor flared connections are a common problem with ductless sys- tems, so be sure to follow best practices when making these connections. After cutting refrigerant tubing, point the cut end of the tubing toward the ground as you deburr or ream the inside edge. This way, any small tubing particles will fall out of the tubing. Ductless systems do not have a filter- drier to eliminate contaminants, so extra care is required. When making the flared connection, use a torque wrench to torque the flare nut to the specification in the installa- tion manual. After the refrigerant line connections, wiring connec- tions, and drain connections have been made, the system is ready to be commissioned. First, the system is pressure tested. Follow the manufacturer’s instructions, but a pres- sure test is likely to be in the range of 500 psi for 24 hours. Using nitrogen for pressure test rather than air is prefer- able because using air introduces additional moisture into the system. Once the system passes the pressure test, the system is evacuated using the triple-evacuation method. The third evacuation generally must pull a vacuum of less than 500 microns. This evacuation is critical to ensure that mois- ture and any other contaminants are cleared from the sys- tems before refrigerant is added. Charge with refrigerant after the evacuation is complete. Manufacturer’s Training for Ductless Systems Manufacturer’s training is the best way to prepare for installing and servicing ductless systems. These systems use proprietary control systems, and installation and service guidelines vary from system to system. The more training you receive, the better your installations and service will be. Pro Tip RectorSeal Figure 32-40. This wall bracket allows an indoor unit to be securely held in place while connections are made. Indoor unit Line set cover Line set 3" hole in exterior wall Shcherbakov Ilya/Shutterstock.com Figure 32-39. A line set from the outdoor unit passes through the building’s exterior wall and connects to the indoor unit.

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Page 2Section 1—Professional Development click to expand contents

Page 52Section 2—Refrigeration System Fundamentals click to expand contents

Page 98Section 3—Service Basics click to expand contents

Page 158Section 4—Refrigerants click to expand contents

Page 258Section 5—Basic Electricity, Magnetism, and Electronics click to expand contents

Page 312Section 6—Motors and Electric Control Systems click to expand contents

Page 418Section 7—Refrigeration System Components click to expand contents

Page 584Section 8—Domestic Refrigerators and Freezers click to expand contents

Page 660Section 9—Indoor Air Fundamentals click to expand contents

Page 776Section 10—Air-Conditioning Systems click to expand contents

Page 990Section 11—Heating Systems click to expand contents

Page 1184Section 12—Energy Management and Conservation click to expand contents

Page 1244Section 13—Commercial Refrigeration Systems click to expand contents

Page 1310Section 14—Designing Commercial Refrigeration Systems click to expand contents

Page 1360Section 15—Installing and Servicing Commercial Refrigeration Systems click to expand contents

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