8 Basic HVAC Parts in Every HVAC System | HVAC

As we have already discussed BASIC PRINCIPLES OF HVAC SYSTEM, Here we can see basic parts of every HVAC system

When all parts of an HVAC system are functioning correctly, it is more efficient. This means it uses less power to accomplish heating and cooling functions, and therefore, it costs the owner less money in electric or gas bills. It is important for owners to conduct regular maintenance on their HVAC systems to keep them functioning optimally. 

1. Furnace

The furnace is typically fairly large and often installed in the basement, attic, or a closet. It is filled with hot water, air, or steam and pushes cold or hot air outward into the ducts that run through every room in the building. Throughout the ducts, vents allow warm or cool air to pass into rooms.
2. Heat Exchanger
Heat exchangers reside in the housing of every furnace unit. When the thermostat activates the furnace, the heat exchanger begins to function as well. Air is sucked into it, either from outside or a separate duct that pulls cool air out of the building's rooms. This type of duct is called a cold air return chase. When the cool air comes into the heat exchanger, it is quickly heated and blown out through the ducts to be dispersed in the building. If the furnace operates on gas, the heating is accomplished by gas burners. If it uses electricity, it is done via electric coils.

3. Evaporator Coil

Like heat exchangers, evaporator coils are also part of the furnace unit but serve the opposite function and are attached to a different part of the furnace. Instead of being within the furnace housing, they are installed inside a metal enclosure affixed to the side or the top of the furnace.

Evaporator coils are activated when cool air is needed. When triggered, they supply chilled air, which is the furnace blower picks up and forces along the ducts and out through vents. The internal design of an evaporator coil resembles that of a car's radiator. Evaporator coils are connected to the HVAC system's condensing unit, which is typically located on the exterior of the building.

4. Condensing Unit

The condensing unit is installed outside the building, separate from the furnace. Inside it, a special kind of refrigerant gas is cooled through the exchange of heat with the air outside. Then, it is compressed and condensed into liquid form and sent through a tube or line made of metal. These parts run straight to the evaporator coil. When the liquid reaches the coil, a series of small nozzles spray the liquid, lowering its pressure and allowing it to expand back into gaseous form. During the evaporation, heat is absorbed, causing a sudden drop in temperature and supplying cold air for the furnace blowers. The refrigerant gas is then sent back outside to the condensing unit, and the process is repeated again to generate additional cold air.

5. Refrigerant Lines

The refrigerant lines are the metal tubes that carry the liquid to the evaporating coil and return the gas to the condensing unit. Commonly made from aluminum or copper, they are designed to be durable and functional under extreme heat and cold.

6. Thermostat

The thermostat controls the function of the furnace. Directly connected to the furnace through wires, it has temperature-sensing technology as well as user controls. Moreover, it is usually positioned on a wall where it can easily discern temperature and remain accessible. A large building may have more than one thermostat to control different areas. The people inside can manually set the thermostat to a certain temperature. If the air in the room or building is too cold, the heat exchanger kicks in and blows heat through the vents like a fan. If the room is too warm, the condensing unit and evaporator coil start to function, and the air conditioning system sends cool air throughout the building or to one particular section of the building.

7. Ducts

Heating ducts are installed during the construction of a home or a building. They are often run through the ceiling. In each room, at least one rectangular opening is cut into the duct so that a vent or vents can be installed. Sometimes, dampers are installed to regulate air flow. The air handler, or AHU, often attaches to the duct system as well and regulates air circulation as part of the ventilation system. 

8. Vents

It is typical to have vents placed in the ceiling, with their edges corresponding to the opening in the duct above. As warm or cool air pours through the ducts, vents allow it to disperse into the rooms below. Vents are usually made of metal, which can handle a wide range of temperatures. The vent is comprised of a rectangular edge or frame, within which is a series of thin, metal slats angled to channel the air downward. Some also include a manual control that lets users change the angle. 

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