What is Local Central HVAC System and Its Types, Working

Local Central HVAC System

Some buildings have multiple zones or a large, single-zone, which necessitates the use of central HVAC systems to serve and meet the thermal requirements. Other structures, such as small houses and residential apartments, may have a single zone that requires equipment to be located within the zone. This type of system is referred to as a local HVAC system because each piece of equipment only serves its own zone and does not cross into adjacent zones.

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As a result, to activate the local HVAC system, a single zone only requires one point control point connected to a thermostat. Multiple local HVAC systems serve specific single zones in some buildings and are controlled by the one-point control of the desired zone. These local systems, on the other hand, are not connected to or integrated with central systems, but they are still part of a larger full-building HVAC system.

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 Local Heating In Central HVAC System

A single zone will require a complete heating system that includes both a heat source and a distribution system. Portable electric heaters, electric resistance baseboard radiators, fireplaces, and wood stoves, and infrared heaters are just a few examples.

Local Cooling System

Local cooling systems can include active systems as air-conditioning systems that provide cooling, a proper air distribution inside a zone, and control of humidification, and natural systems as convective cooling in the open windows, evaporative cooling in fountains.

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Local ventilation systems

Local ventilation systems can be forced by using devices like window fans to allow air movement between the outdoors and a single zone while maintaining the zone's thermal environment. Other ventilation systems include air circulation devices such as desk or paddle fans, which improve thermal comfort by allowing heat to be transferred in a conventional manner.

Local air-conditioning systems

A complete local air conditioning system includes a cooling and heating source, a circulation fan, a filter, and control devices. 

The three major types are listed below:

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• Window air-conditioner
• Unitary air-conditioner
• Packaged rooftop air-conditioner

Window air-conditioner

This system is a packaged unit that includes a vapour compression refrigeration cycle with a compressor, condenser, expansion valve, and evaporator, as well as a fan, filter, control system, and housing. Window air conditioners can be installed without ductwork in a framed or unframed opening in a building wall or in window openings to effectively distribute cooling or heating air inside the conditioned space. The air conditioner has both an evaporator and a condenser, with the condenser outside the space and the evaporate inside, but it serves the entire single zone with its thermal requirements. Adding an electric resistance coil to the air conditioning system or reversing the refrigeration cycle to act as a heat pump can be used to heat the space. Many feature designs are created to add aesthetic value to the product while also improving its quality and response.

Unitary air-conditioner

From an equipment standpoint, it is similar to window air conditioners, but it is designed for commercial buildings. It's mounted on the building's exterior wall, usually near the intersection of the floor and the wall. Every zone will have a single unitary air conditioner, similar to the ones found in many hotel rooms.

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A packaged rooftop air-conditioner

A vapor compression refrigeration cycle; a heat source, such as a heat pump or electric resistance; an air handler, such as dampers, filters, and fans; and control devices make up the system. This system can be connected to ductwork and used to cool a large single zone that unitary or window air conditioners can't reach.

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Split systems

The condenser, which is located outside, and the evaporator, which is located inside, are the two central devices in split systems. A conduit for refrigerant lines and wiring connects the two devices. Because the location and installation of window, unitary, or rooftop air conditioners can affect the aesthetic value and architectural design of the building, this system addresses some issues with small-scale single-zone systems. One condenser unit can be connected to multiple evaporator units in a split system to serve as many zones as possible under the same or different environmental conditions.