A brief explanation on how air conditioning works and what terms mean

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1 A brief explanation on how air conditioning works and what terms mean -presented by- Before we begin, let s explain the air conditioning process. In the most basic of terms, air conditioning simply takes heat from a place that you don t want it and moves it to an area you do. There are many components that are used to make that happen of course, but if you think of it in this way it becomes very easy to break it down. It also helps to know that heat is energy, and what we are doing is moving energy as if it were something we could hold. Think of it as water for your outdoor plants, where you can put it in a can at the kitchen sink and transport it wherever you need, only to be used later. In much the same way, air conditioning takes the heat energy from your home and carries it outside for you. The system does this thru the use of four major components and all of these are found in every A/C systems. The condenser, the evaporator coil, the line set, and the refrigerant. So, what do they do? Evaporator coil- Sometimes referred to as the A-Coil because of its appearance (the actual coil looks like the letter A ), the evaporator is the piece that mounts inside of the furnace duct. Its purpose is to transfers heat from the air in your home to the refrigerant. When the furnace blower moves the air across the evaporator coil, the fins pick up the heat from the air and conduct it to the refrigerant. Refrigerant- This is the gas that stores and then transports the heat energy. It travels thru the evaporator, picking up the heat from the air, absorbing that energy as water does when you boil it on the stove. As with water, refrigerant can hold a LOT of heat (water still looks like water whether its 40 degrees or 200 degrees but its holding a lot of energy at that higher temperature). It carries it thru the line set to the condenser outside where it is then rejected to the outdoor air. There are typically two types of refrigerant for home air conditioners; Freon and Puron.

2 Line set- This is the copper tube that runs from your furnace to the condenser outside and is the pipe that the refrigerant travels thru. It needs to be insulated on the larger pipe with a product commonly called armaflex. This is due to condensation that occurs on the pipe if it is not insulated (this happens because the refrigerant is still trying to pick up heat even after it leaves the evaporator ). Condensing unit- The condensing unit is the piece of equipment that sits outside. Its purpose is to reject the heat from the refrigerant, cooling it back down until it turns into a liquid so it can travel back to the evaporator to pick up more heat from the home. Much as a radiator does for a car or a desk fan does for you, the condensing unit uses a condenser fan motor to blow air across the condenser coil and remove the heat that the refrigerant picked up. The compressor moves the refrigerant thru the system here as well. This is the core of your air conditioner and requires the most amount of maintenance. Ok, now that we understand the basics lets get into more detail. The following is a list of specific parts, terms, and techniques that are used in air conditioning. They will be put into relation with one of the four components listed above and are listed in alphabetical order. A-Coil- Is simply a nick-name for the evaporator. Armaflex- This is the black, spongy material around the larger, suction line of the line set and is an insulation to protect against condensation or the pipes sweating. Brazing- A technique of sealing two joints by means of a brazing rod (a flux core welding rod bearing some silver content) and high temperatures (typically acetylene gas). Brazing is the preferred method of connecting joints in an HVAC system since it produces an actual weld that will be stronger than the pipes it joins. It requires special equipment and training to perform, which is why it is only seen on higher quality installs. Brazing is crucial on newer, puron systems because of the higher internal pressures. BTU- Is an anagram for British Thermal Unit and is a way of describing heat energy. The true definition is as follows- A BTU is the quantity of heat required to raise the temperature of one pound of water from 60 to 61 F at a constant pressure of one atmosphere. This term is used not only for cooling but also for heating. Cap Tube- Similar to the thermal expansion valve, this was a monitoring device for the refrigerant going thru the evaporator. This one, however, does not modulate in regards to load. Common on much older systems, Cap-tube devices have almost been eliminated due to the increased performance provided by a TXV and the problems an unmonitored flow of refrigerant can cause on newer installations. Cap tube failures are typically caused by debris.

3 Capacitor- This is a device that stores electricity and then delivers it in a quick, high voltage jolt (typically appearing as a small, silver cylinder). Much like pushing a merrygo-round, it is used on compressors and condenser fan motors to kick-start them and/or to keep them spinning. This simple part can be a cause for a complete condenser failure. This part usually fails due to the condenser being hit by a voltage spike. Certification- This is simply a nick-name for EPA refrigerant certification. Comfortalert- This is a diagnostic board mounted on some brands of air conditioners. This helps a technician with troubleshooting your system. Usually only found on higher end units, this module monitors a variety of system points to tell a service person if your condenser is having problems with high or low voltage, excessive head pressure, if the unit low on charge, etc. Charge- This is simply a nick-name for system charge Compressor- Often appearing as a black barrel, this is the heart of the air conditioning system. Like a beating heart, it moves the refrigerant thru the system, pushing it thru the various components. There are two basic styles; rotary and scroll. Air conditioning compressors are different from air compressors, but do perform the same basic function (which is to compress gases). This compression is crucial to the function of the refrigerant in regards to releasing the heat energy that it has stored from the evaporator. This is the most costly part of the air conditioner, and is the most common cause for system failure. With proper maintenance, the typical life span of a compressor is 15 to 20 years. Contactor- This is the switch mounted on the condenser that activates it. When the thermostat calls for cooling, a low voltage (24v) signal is sent to this switch, which pulls in a set of contacts and delivers 230 volt power to the unit. Contactors typically fail due to electrical scoring or bugs, debris, etc. getting into them. Condenser Coil- This is the area that is typically the most visible on a condenser. It is usually found in one of two styles, either as a fin type (appearing as a car radiator) or as a spine type (appearing as a bristle brush). They are normally made of aluminum and/or copper and conduct the heat from the refrigerant by the use of the condenser fan motor blowing outdoor air across it. Because of this, it is crucial to keep the fins clean of dirt or debris (this is the area being rinsed during a clean and check ). Dirty condenser coils are the most common cause of compressor failure. Condenser Fan Motor- This is the motor that acts in much the same way as a desk-top fan motor does. It turns a fan blade, blowing cool air across the condenser to drop the temperature of the refrigerant as it passes thru the condenser coil. Its voltage (usually 230v) matches that of the condenser and is the motor typically found at the top of the unit. Because of their location and exposure to harsh conditions, bearing seizure is their main reason for failure.

4 Disconnect- This is the mid-sized electrical box mounted on the outside the home, usually with a lever on the side (it is often grey in color). This is either a fused or nonfused style and is the safety switch to completely eliminate power to the condenser for installation or service. Electrical Whip- Sometimes called a whip, this is a flexible, weather-proof electrical conduit that connects the condenser to the disconnect. EPA Refrigerant Certification- This is a license that MUST be carried by anyone handling, transporting, or working with refrigerant. Failure to possess or produce this license will result in a fine of $10,000 per infraction on a residential system. To gain this license a technician must pass a test as to the dangers, handling, and disposal of refrigerant. In addition, many manufactures require an additional certification for installation of their specific brand of puron systems. Filter Drier- This piece is hard piped into the system and protects the internal components from things such as debris, acid, moisture, and dirt that can be carried inside the system by the refrigerant (either pre-existing or when a charging of the system is done). It captures and holds these harmful substances before they can destroy the system. It typically only needs to be replaced with a system changeout. Flux- An acid bearing material that is used to clean the pipe and joints of any contaminants such as oil or dirt. Such contaminants can not allow a solder to flow, resulting in a poor or leaking joint. Flux if used incorrectly can enter into an air conditioning system and destroy important components, especially if a filter drier isn t used. Freon- Also referred to by its chemical designation of R22, this is an older style of refrigerant that has been mandated by the EPA for phase out. Commonly found on older system, this gas was a leading cause of ozone depletion. As of 2010, equipment using this refrigerant can no longer be manufactured. As of 2020, the product will be phased out entirely. It is not compatible with puron or equipment that uses puron. H-Coil- Is simply a nick-name for the evaporator but is for horizontal furnace applications Liquid Line- This is the smaller of the two pipes found on the line set and carries the refrigerant from the condenser to the furnace so it can pick up heat at the evaporator. Mounting pad- Is simply a nick-name for the pad. N-Coil- Is simply a nick-name for the evaporator but is shaped line an N to conserve on space.

5 Orifice- Similar to the thermal expansion valve, this is a monitoring device for the refrigerant going thru the evaporator. This one, however, does not modulate in regards to load. Common on older systems, orifice devices have almost been eliminated due to the increased performance provided by a TXV and the problems an unmonitored flow of refrigerant can cause on newer installations. Debris is their most common reason for failure. Pad- Or mounting pad, this is the slab that the outdoor condenser is placed upon. There are several styles of pads, ranging from concrete to clad-lite (which is styrofoam dipped in concrete), from syrofoam to just a bed of gravel. UV resistant resin pads are the latest innovation, providing a light weight base that also won t crack, warp, fade, or peel. Puron- Also referred to by its chemical designation of R410a, this is the replacement refrigerant for freon. Giving better performance at higher head pressures than freon, this product will be available in the future. It is not compatible with freon or equipment that uses freon. R22- Is simply a nick-name for freon. R410a- Is simply a nick-name for puron Rails- Sometimes called mounting brackets, certain outdoor condensers were mounted on these in lieu of using a pad. They are angle brackets that are typically secured to the foundation of the home to prevent settling of the unit or to keep it off of the ground entirely. Rotary compressor- Much like a car engine, this compressor style uses a cylinder, piston, and valve design to compress the refrigerant gas. Scroll compressor- This compressor design uses the concept of squeezing the refrigerant between two solid plates to compress the refrigerant gas. Short Cycling- This condition is when the system runs for short periods of time and then turns off, only to restart minutes later. Slugging- This is when liquid refrigerant returns to the compressor. When traveling thru the evaporator, the refrigerant should be turned 100% gaseous as a compressor cannot handle liquid. Since liquids cannot be compressed, this damages the compressor. This is a primary reason new systems use thermal expansion valves, as they protect against slugging. Short Cycle control- Sometimes referred to as a brown-out control, this protects the compressor from slugging by providing a time delay to the unit. Certain thermostats or condensers have this protective feature built in.

6 Soft Soldering- Sometimes referred to as just soldering, this is a technique (normally only found in plumbing applications) of joining two pipes thru means of a soldering material (typically lead). The solder fills the voids between the pipe joints, plugging up the gap to produce a seal. Because it simply fills gaps instead of permanently welding pipes as brazing does, soft soldering is no longer an acceptable method of sealing joints on the new, higher pressure puron systems. In addition, an acid bearing flux is used with soft solder, which can contaminate the internal components of a system if a filter drier isn t used. Suction line- This is the larger of the two pipes found on the line set and carries the refrigerant from the evaporator in the furnace to the condenser. This is so the heat that the refrigerant has picked up can be rejected outside. It is insulated with armaflex. System Charge- This term refers to the amount of refrigerant contained within the system. Each system has a unique charge. This is based on many things, such as its tonnage, the length of the line set, and even the type of refrigerant. This can be done one of two ways, either with gauges and pressure/temperature charts or by weighing in the charge with an electronic scale. Systems with a low charge will exhibit signs of the evaporator freezing, ice at the condenser, or simply not cooling enough. Systems with a high charge will exhibit signs of liquid lines sweating, noisy compressors, or short cycling. Refrigerant Certification- Is simply a nick-name for EPA refrigerant certification Thermal Expansion Valve- This mounts on some evaporators and is used to monitor the refrigerant going thru it. A system that is monitored by a thermal expansion valve has less of a tendency for slugging the compressor because the TXV modulates in regards to the temperature of the system. Simply put, a TXV only lets as much refrigerant flow thru the system as you actually need. As your load increases, so does its flow. Debris in the system is their most common reason for failure. Tonnage- This is a language to designate the size of a condensing unit. Why the term tonnage? Because before there was air conditioning, movie houses would roll one ton blocks of ice into the theater to keep the audience cool. One ton of ice can absorb12,000 BTUs of energy in a 24 hour time period as it melts, thus the term. It stuck. So now a system s size will be termed in this way, calling out 3 tons of cooling as example. This simply means that it removes 36,000 BTUs (12,000 x 3 = 36,000) of heat from your home. TXV- Is simply a nick-name for the thermal expansion valve Whip- Is simply a nick-name for the electrical whip.

7 We here at Armbrust Plumbing, Heating, and Air Conditioning hope that these definitions help you better understand some of the products, techniques, and concepts that go into your air conditioning system. We truly believe that if you know what is involved in a quality installation, you will choose us every time. If you have any additional questions or want something explained in more detail, please don t hesitate to call us at or simply ask your installer. You ll find he s happy to explain!