The discharge air from the parallel fan powered terminal is a combination of primary air from the central air handler, and fan air volume pulled from the surrounding plenum. HX refers to the evaporator, condenser or the cooling coil of an air conditioner or a chiller. It can be any type including finned-tube heat exchanger which is commonly found in residential split air conditioners or shell-and-tube heat exchanger which is more commonly found in water-cooled chiller. Unlike AHUs, FCUs operate independently within their designated areas. They are connected to a central heating and cooling system through pipes that supply hot or cold water.

Introduction to Terminal Units

Examples of ERU include ERV, heat wheel and heat pipe. Generally, ERU recovers the energy from the exhaust air or unwanted air to the outdoor air that’s being introduced into the system. It saves energy and improve the efficiency of the air conditioning system. ERV is an energy recovery devices that often transfer the heat from the incoming outdoor air to the outgoing exhaust air. BTU is the most common unit of measurement for air conditioner cooling and heating capacity.

Fan coil unit

LRA is an important value to account for when designing a power surge protection system. DHU is designed to remove water vapor or dehumidify much more effectively than conventional AHU. It can deploy components such as desiccant to improve the dehumidification capability of the system. CP is commonly found in layout and panel drawings. AHUs and FCUs usually have a CP nearby or within the same room. Sometimes, DB which stands for distribution box is used instead of CP.

• As the demand in the spaces fluctuate the VAV box dampers open or close proportionately and the air handler fans respond through various control strategies.
• The supply air main is considered the high side of the system.
• They generally consist of rows of smooth copper tubes mechanically expanded into thin aluminum ‘fins’, which increase the effective heat transfer area of the device.
• A terminal unit is a device that is used to regulate the volume of conditioned primary air from the central air handler to the occupied space.

Single Duct

RLA is the electric current drawn by a motor or compressor when operating under the rated conditions. For example, if the compressor of an air conditioner has a RLA of 10A, it means the electric current drawn by the compressor is 10 amps when the outdoor temperature is 95°FDB / 75°FWB. The outdoor temperature of 95°FDB / 75°FWB is where the air conditioner is tested or rated on. LPS is commonly found in compressor and refrigeration system.

VVT stands for Variable Volume and Temperature. VVT is used in VRF/VRV system to describe the ability to change the refrigerant volume and the refrigerant temperature. By default, VRF/VRV systems are capable of changing the refrigerant volume. However, some VRF/VRV systems have the capability to change the refrigerant temperature for better comfort and energy efficiency. SEER stands for Seasonal Energy Efficiency Ratio. SEER indicates the energy efficiency of an air conditioner in cooling.

Variable Volume Single Duct

It burns fuel to generate heat for air conditioning. AC is a generic term used to indicate an air conditioner, regardless of the type. The air conditioner can be AHU, FCU or any other type that provides airflow and air conditioning to a room. ATC is used to indicate the temperature and humidity in certain sections/zones of a building is automatically controlled by the air conditioning system. AHUs can also be designed to serve specific needs, such as cleanrooms in pharmaceutical manufacturing or data centers where precise temperature and humidity control are critical.

It is internationally recognized as a high-efficiency filter material and is widely used in operating rooms, animal laboratories, crystal experiments, and aviation, among other highly clean places. EAF air-conditioning exhaust fan is mainly used in the public areas of the floor, such as corridors, stair front rooms, etc. It refers to filter screens that vav vs fcu meet the HEPA standard, with an efficiency of 99.998% for 0.1 microns and 0.3 microns. The characteristic of HEPA mesh is that air can pass through, but fine particles cannot pass through.

Non-Mixing Dual Duct

In high-rise buildings, fan coils may be vertically stacked, located one above the other from floor to floor and all interconnected by the same piping loop. The output from an FCU can be estimated by measuring the temperature difference between the air entering and leaving the unit, coupled with the volume of air being moved through the unit. This is a simplistic statement, and there is further reading on sensible heat ratios and the specific heat capacity of air, both of which have an effect on thermal performance. DOAS offers energy saving benefits which complement the design goals of Green/LEED buildings. Fan Filter Units (FFU) are terminal purification equipment that combines fans and filters (high-efficiency filters (HEPA) or ultra-high-efficiency filters (ULPA)) to create a self-powered unit.

• RAD is usually located at the center of the duct on a drawing.
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• Upon energized, it will physically lid and close the circuit thereby allowing electricity to pass through and start the indoor fan motor.
• PHAU is a type of air handling unit that processed the outdoor air.
• Engineers apply the knowledge of math & science to design and manufacture maintainable systems used to solve specific problems.

ECM has a motor efficiency class rating of at least IE3 and above. DX refers to air conditioners that use refrigerant as the medium of heat transfer to cool the air. Examples of DX systems include split air conditioners, multi-split air conditioners, and VRF/VRV systems. Contrarily, non-DX or indirect expansion refers to equipment like chillers which use chilled water as the medium of heat transfer instead of refrigerant. ACU is a generic term used to indicate an air conditioning unit, regardless of the type.

Electric Reheat Coils for Terminal Units

CWS is commonly found in the chilled water system layout and schematic drawings. It is also common to have the CWS word physically painted on the condenser water pipe to indicate the condenser water flow direction from the cooling tower to the chiller. The pressure sensor is set to maintain a constant pressure in the main supply duct which often causes excess static pressure to be provided when compared to option two below. The reduction in the fan speed provides energy savings.

For example, a chiller system with N+1 design means it could have 4 chillers on duty and 1 chiller as backup. NRD is a type of damper that allows air to move in one direction only. It utilize the force of gravity and material weight to close. When air is moving in the correct direction, the mechanism of NRD allows it to open thereby letting the air to flow through. But, if the air moves in the wrong direction, the NRD blades will fall due to gravity, effectively prevent the air from passing through.