Heating, Ventilating, and Air Conditioning (HVAC) equipment perform heating and/or cooling for residential, commercial or industrial buildings. The HVAC system may also be responsible for providing fresh outdoor air to dilute interior airborne contaminants such as odors from occupants, volatile organic compounds (VOC’s) emitted from interior furnishings, chemicals used for cleaning, etc. A properly designed system will provide a comfortable indoor environment year-round when properly maintained.

Top 10 HVAC

Bestseller No. 1
Modern Refrigeration and Air Conditioning (Modern Refridgeration and Air Conditioning)
207 Reviews
Modern Refrigeration and Air Conditioning (Modern Refridgeration and Air Conditioning)
  • Andrew D. Althouse, Carl H. Turnquist, Alfred F. Bracciano, Daniel C. Bracciano, Gloria M. Bracciano
  • Goodheart-Willcox
Bestseller No. 2
Testo 0563 0002 Refrigeration Wireless Smart Probe Set
62 Reviews
Testo 0563 0002 Refrigeration Wireless Smart Probe Set
  • Measure high-side & low-side refrigerant pressure & temperatures (simultaneously) of ac/refrigeration systems
  • Low-loss ac/r system checks. Not hoses required
Bestseller No. 3
Hvac Technician Hourly Rate T Shirt I Air Conditioner Wiring
  • This hvac technician t-shirt sets everyone whose job it is, to repair the electronics in air conditioners up...
  • Awesome for adults, men, women. A great gift idea for christmas, a birthday, an anniversary, or any other...
Bestseller No. 4
Klein Tools 32596 Screwdriver / Nut driver 8-in-1 HVAC Multi Tool
98 Reviews
Klein Tools 32596 Screwdriver / Nut driver 8-in-1 HVAC Multi Tool
  • Unique, patented head slides back and forth to switch from 1/4-Inch to 5/16-Inch magnetic hex-head screwdriver
  • Thumb nut locks tip setting
Bestseller No. 5
HVAC Equations, Data, and Rules of Thumb, Third Edition
23 Reviews
HVAC Equations, Data, and Rules of Thumb, Third Edition
  • Arthur A. Bell, W. Larsen Angel
  • McGraw-Hill Education
Bestseller No. 6
Central Air Conditioner Tune-Up
11 Reviews
Central Air Conditioner Tune-Up
  • Service provided by a local pro
  • Inspection of all parts and levels
Bestseller No. 7
Mens HVAC Funny Shirt - When The Ladies Get Hot They Call Me
1 Reviews
Mens HVAC Funny Shirt - When The Ladies Get Hot They Call Me
  • HVAC Funny Shirt - When The Ladies Get Hot They Call Me
  • If you're looking for HVAC gifts then you found the best HVAC funny shirt.
Bestseller No. 9
HVAC Tables, Equations & Rules of Thumb Quick-Card
57 Reviews
HVAC Tables, Equations & Rules of Thumb Quick-Card
  • Builders Book, Inc.
  • Builders Book, Inc.
Bestseller No. 10
Imperial 535-C Kwik Charge Liquid Low Side Charger
83 Reviews
Imperial 535-C Kwik Charge Liquid Low Side Charger
  • Price For: Each Fitting Material: Brass Item: Liquid Charging Adapter Connection Size: 1/4" Male x 1/4" Female...

How does my AC work?

An air conditioner cools and dehumidifies the air as is passed over a cold coil surface. The indoor coil is an air-to-liquid heat exchanger with rows of tubes that pass the liquid through the coil. Finned surfaces connected to these tubes increase the overall surface area of the cold surface thereby increasing the heat transfer characteristics between the air passing over the coil and liquid passing through the coil. The type of liquid used depends on the system selected. Direct-expansion (DX) equipment uses a refrigerant as the liquid medium. Chilled-water (CW) can also be used as a liquid medium.

When the required temperature of a chilled water system is near the freezing point of water, freeze protection is added in the form of glycols or salts. Regardless of the liquid medium used, the liquid is delivered to the cooling coil at a cold temperature.

As this liquid passes through the indoor cooling coil on the inside of the heat exchanger, two things happen to the air that passes over the coil’s surface on the outside of the heat exchanger. The air’s temperature is lowered (sensible cooling) and moisture in the air is removed (latent cooling) if the indoor air dew point is higher than the temperature of the coil’s surface.

What type of AC systems are available?

A split system is a combination of an indoor air handling unit and an outdoor condensing unit. The indoor air handling unit contains a supply air fan and an air-to-refrigerant heat exchanger (or cooling coil), and the expansion device. The outdoor condensing unit consists of a compressor and a condenser coil. Split-systems are typically found in residential or small commercial buildings. These systems have the highest energy efficiency rating (EER) of all the available AC systems.

Manufacturers are required to take the EER rating a step further and provide a seasonal energy efficiency rating (SEER) for use by consumers. SEER ratings vary widely and range from 10 to 20. The higher the SEER rating, the more efficient the AC system operates. If heating is required, an alternate method of heating the interior of the building must be used, usually in the form of electric or gas heating.

Cooling Only Packaged-System

A packaged system is a single unit combining all the components described in the split system. Since the unit is a package, it must be placed outside the building and indoor air is “ducted” from the building to the packaged system and back through an air distribution system. These units typically have SEER rating from 10 to 18. If heating is required, an alternate method of heating the interior of the building must be used, usually in the form of electric or gas heating.

Heat Pump

Heat pumps are similar to cooling only systems with one exception. A special valve in the refrigeration piping allows the refrigeration cycle to be operated in reverse. A cooling only system cools the indoor air and rejects heat to the outdoors. A heat pump can also cool the indoor air, but when the valve is reversed, the indoor air is heated. A supplementary electric resistance heater may also be used to assist the heat pump at lower outdoor temperatures. In colder climates, heat pumps require a defrost period. During defrost, times the electric heater is the only means of heating the interior of the building. These units are manufactured as either split or packaged systems.

Chilled Water System

In a chilled water system, liquid water is pumped throughout the building to “chilled water coils”. Since the liquid water needs to be at a cold temperature, a “cooling plant” is required. The plant is typically referred to as a chiller plant. Vapor compression equipment in the plant, similar to that described in “How does my AC work”, cool water to a cold temperature and pump the cold water to air-to-water heat exchangers where needed.

Window Air Conditioners

As the name implies, a window air conditioner is typically installed in a window or custom opening in a wall. The Window AC can only cool small areas and are not intended to provide cooling to multiple rooms or zones. These air conditioners are manufactured as cool only or can provide both cooling and heating. An optional damper in the unit can provide fresh outdoor air if necessary.

Packaged Terminal Heat Pump

Packaged terminal heat pumps (PTHP) are similar to a window-mounted air conditioner. These units are typically installed in a sleeve passing through the outdoor wall of an apartment, hotel, school classroom, etc. PTHPs are completely self-contained and require only an electrical connection in addition to the opening in the building shell. They use the outdoor air as the heat source in winter and as a heat sink in summer. They also can provide ventilation air. Flexibility and lower installed cost are the primary advantages of the PTHP. Disadvantages include in-room maintenance, higher operating cost, relatively short life, imprecise “on-off” temperature control, and they can be rather noisy.

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