Lesson 4. Learning to Speak HVACR

Like most industries, the air conditioning industry has many unique words, acronyms and tech speak.  We need to try and speak HVAC Basic Standard English when talking to the public and customers in order to help them understand our industry.  You should understand HVACR jargon so you can communicate with the HVACR geeks, but as with any communication the best practice is to use the smallest word that will accurately communicate what you’re trying to say.

Here are some of the HVAC Basic terms describing the primary components used in HVACR and a short description of what they do:
Heating units and components
• Furnace:  A furnace is a heating unit that is usually fueled by natural gas, propane, oil, electricity or hot water.  The furnace has a fan that moves air across the heat exchanger that heats air and distributes the heated air to heat the building.
• Heat Pump:  A heat pump is an air conditioner running in reverse.   Heat Pumps remove heat from the air using an aluminum fin coil and reject the heat into the air through another coil.  It can move the heat from outdoor to indoor or indoor to outdoor.  The Heat Pump uses a reversing valve to reverse the cycle from cooling mode to heating mode.  The source of heat is usually air but can also be water or the ground.  A ground source heat pump is also called a Geothermal Heat Pump.
• Boiler:  A boiler is a common source of heat in some parts of the country.  Most heating boilers are large water heaters.  Larger commercial boilers can produce steam instead of hot water.  The hot water is pumped to an air distribution unit containing a coil and fan.  These units are commonly known as Fan Coil Units (FCU) or Air Handling Units (AHU).  They serve the same purpose as a furnace.  Other heat distribution devices that do not use a fan can also be used such as baseboard heaters or in floor piping that heats the floor.
• Heat Exchanger:  A heat exchanger is a device that transfers heat from one medium to another.  The most common heat exchanger is the aluminum fin coil that transfers heat from the refrigerant inside the tubing through the aluminum fins and into an air stream.  Another type of heat exchanger transfers heat from a gas flame through a steel plate to the air stream on the other side.  The primary reason for this type of heat exchanger is to keep the poison combustion gas separate from the air circulated indoors.  Other heat exchangers might transfer heat from water to air or air to water.
• Burner:  A burner controls the flame and flame efficiency from a fuel source such as natural gas or fuel oil.  Burner systems also include safety controls.

Air Conditioning
• Split System:  This is a very common variation of an air conditioning system.  The split means there are separate indoor and outdoor units connected by refrigerant pipe.  The outdoor unit usually contains a heat exchanger consisting of a tube and fin coil.  This heat exchanger moves the heat in the refrigerant gas to the outdoor using a fan blowing air across the coil.  The outdoor unit also includes a pump or compressor that pumps up or re-compresses the refrigerant gas.  The compressed and condensed liquid refrigerant is transferred through copper tube to the inside unit that contains an expansion device and another copper tube and aluminum fin heat exchanger coil.  This coil absorbs the heat from inside the building using a fan that moves the air across the coil.  The heat is transferred to the refrigerant and is piped outside to start the process again.  The expansion device transforms the liquid refrigerant to a gas allowing it to pick up massive amounts of heat.  Cooling is defined as the absence of heat.
• Self Contained Unit:  A self contained unit works the same way as a split system except that all the components are in one box.  This unit can also call a rooftop unit (RTU) when it mounts on a roof.
• Chilled Water System:  A Chilled Water system is a larger commercial system.  It works much like a split system except that the refrigerant travels through a heat exchanger that transfers heat from the water in the chiller to the refrigerant in the tubes.  In the chiller the water surrounds the refrigerant tubes.  The chilled water is pumped into the building and absorbs heat from the air utilizing a chilled water coil made of tubing and aluminum fins much like a refrigerant coil in a split system.
• The heat exchangers are classified by their function.  The heat exchanger removing the heat and cooling the air indoor is called the evaporator coil.  This term comes from the process where the liquid refrigerant changes from a liquid to a gas in the coil.  (it evaporates)  The condenser coil is usually outside and rejects the heat from the refrigerant to the outdoor air.  This heat exchanger coil is called the condenser coil.  (condenses the gas back to a liquid as it rejects the heat to the outside air)
• Types of Chillers:  Chillers are categorized by the type of compressor they contain.  These chiller compressors include reciprocating, screw and centrifugal.

Review and get familiar with these HVAC Basic terms.

One single comment

  1. Gaafar Hamad says:

    iam working as service manager ,it is a very usefultoolfor refreshement for my old technicians and also good start for my newely recruited

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