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Get to Know about Types of HVAC systems

ID Fan manufacturersHVAC (Heating, Ventilation and Air Conditioning) systems are designed to perform four main functions – heating, cooling, ventilation and controlling humidity levels. HVAC systems are designed to meet goals of its customers and satisfy them in terms of efficiency of system and saving energy. Many HVAC systems are available today and are designed for both homes to industries. Selection of HVAC system is critical because improper selection may cause discomfort in terms of health and loss of money. This article tells you about types of HVAC systems.

Though there are many type of HVAC units, there are four broad categories.

Constant air volume (CAV) HVAC systems

Constant air volume HVAC systems work by use of constant supply of air volume by distributing hot or cool air. Constant air volume HVAC systems are installed in large spaced rooms (auditoriums, theaters, lobbies, hospitals, manufacturing units, etc.). There are three variants of CAV systems: single duct, reheat and multi-zone systems.

  • Single duct system: A single duct CAV is a simple central air conditioner with single zone distribution for either cool or hot air throughout the building at a fixed temperature (usually 55O F). This fixing of temperature allows to maximize cooling load in all spaces.
  • Reheat system: The reheat system is modified single-zone distribution system that uses electricity or water to heat coils. Reheat coils reheat the cool air flow and distribute controlled air throughout the building. It is used in hospitals, laboratories and other buildings, which require wide load variation.
  • Multi-zone system: Multi-zone system has two distribution systems, one for heating and other for cooling. Both ducts are designed to meet at one place called “mixing box”. This mixing box controls and distributes the required air temperature throughout the building.

Variable air volume (VAV) HVAC systems
Variable air volume systems are economical to install and are more energy efficient to bring down the cost by 10 to 20% compared to constant air volume systems. This system is best to meet varying cooling and heating needs of building areas.

The design of VAV system is simple and has small units that make installing easier. The main air duct provides cooling at 55O F and this is called primary air. A thermostat controls the temperature of primary air delivered to each room. This modulates the volume of air supply to get the required room temperature in different rooms according to cooling needs.

The main advantage of using VAV comes by its efficiency in dehumidification and temperature control by fan that efficiently reduces over all cooling or heating bills.

Radiant air conditioning (RAC) HVAC systems
Radiant air conditioning system refers to temperature controlled surface (hot/cold water or electrical heating coils tubing) that heats or cools indoor air temperature before air goes into the room. Radiating air conditioners install metal tubing on the surface of ceiling or walls of home or offices.

In this system, as air passes through metal pipes along the the concrete ceiling or walls, it gets warmed or cooled before it goes into the indoor environment. From these tubing, heat or cooling is transferred from ceiling or walls to warm the indoor air. The use of RAC has many advantages – no duct work is required, quite and energy efficient, no need of cool air exchanger, zoning capabilities and finally even temperatures for comfort. RAC is a power saving system that allows users to get comfortable temperature at home under lower temperature.
Advanced radiant RAC systems make it possible to control individual room in buildings. There are different types of radiant air conditioners and the most common types are electrical and gas fired systems.

Zoned System
Zoned system is a single area where temperature is regulated by singe thermostat. If a building’s temperature is controlled by a single thermostat, it is called single-zone. When multiple thermostats are used in a building, it is termed as multi-zone system.

In single zone HVAC system, single thermostat maintains same room temperature across different zones of same building. While in multi-zone system, each room is equipped with one thermostat to receive air with different temperatures based on the need of users.

Multi-zoned system is more advantageous over single-zone, as multi-zone system can efficiently control air-conditioning requirements. They are able to direct hot or cool air for certain rooms when needed. This offers wastage of power utilization for cooling or heating your building.

Use of zoning system enables you to save around 30% or more cooling/heating on power bills. Since zoned HVACs run based on your requirements at single or more rooms, it makes HVAC to run at lower speed and thus run quietly, and hence ergonomically good.

Additional Resources:
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How are Gas Heaters Different from Electric Heaters?

Based on the type of energy source, heaters are divided in to gas heaters and electric heaters. As their name suggests, they work either with gas or electricity. Gas heaters sue natural gases as their power source. Let us now know few details about these two types of heaters.

Gas Heaters: Gas Heaters are mostly used in residence among different countries during winter seasons. Gas heaters are cost effective and they do not use firewood for heating. The gas heaters function cleanly and smoothly. The fuel used in gas heaters are liquified petroleum gas or natural gas. Gas heaters can be dangerous because they easily catch fire. Gas heaters are of two types:

Vented Gas heaters: This device can be mounted on a wall or can also be placed in an existent chimney. On combustion of fuel, the smoke generated escapes safely from a pipe that is present in that device.

Ventless Gas Heaters: It is easy to install but requires to follow lot of precautions. Ventless gas heaters work based on the theory of combustion. It may be dangerous, as they spread out powerful gases, thus it is recommended to install them at a well ventilated spacious room.

Electric Heaters: In these kind of heaters, heat is generated from electric heaters by converting the electrical energy into heat energy. Electric heaters are most commonly used for heating water, cooking, etc. Electric Heaters are of many types – electric garage heater, electric base board heaters, electric Wall heaters, etc.

Based on the easy availability of the above mentioned energy sources (gas or electricity) at your residence, one can select either gas heaters or electric heaters.

How are Central Heaters Different for Space heaters?

There are two major types of heating systems – central heating system and space heating system. Central heating system is that type of heating system which is used to heat large spaces. Whereas, space heating use portable heaters to heat smaller areas.

Let us know few important details about these two kinds of heaters.

Central Heater: A central heating system is used to heat all parts inside a room. It is the most popularly used heating system. The heat generated from central heater flows all over the room in a series of tubes called ducts. Central Heaters mostly work with the help of electricity or gas and at times they also work with coal, wood or heating oil.

Space Heaters: If heating is necessary for a small enclosed area, generally space heaters are used. Space heaters contain capacity that ranges between 10,000 Btu to 40,000 Btu per hour. Some fuels like electricity, propane, natural gas and kerosene are used to maintain the capacity range. Some space heaters are dependent on convection through which movement of air happens in a room and some are dependent on radiant energy through which objects are heated directly from sunlight. The heat generated in a room by space heaters using radiant energy can last only for a few hours. Space heaters can be portable and are usually attached on a wall. Space heaters can reduce the electricity bill when compared to central heaters.

Based on the heating requirements and the areas, one can choose the best suitable heating system.

Comparison of Space Heating and Central Heating

When planning to find home-heating option, it is necessary to know about both central as well as space heating. Here is a comparison of these two modes of heating.

Space heating ensures providing heat for a limited space whereas central heating provides heat throughout your house. Various types of space heaters are available today among which electric and oil-filled ones are used commonly. Central heating mostly uses electricity or gas as power source. Space heating can be preferred if you just need to heat only desired areas of your home. Centralized heating may also heat any unwanted areas of your home like store room and attic which may incur energy or heat loss. So, if you want to avoid unnecessary energy loss due to centralized heating, you can use space heating. Also, space heaters are available in various designs and models which can fit well adding as a décor to your room.

Centralized heating is more expensive when compared to space heating. Fuel requirements, installation as well as maintenance of central heating involve higher prices, even if it uses gas or electricity. Even if you use electric space heaters, they are utilized for less time and even for a limited area. Hence, the energy costs are also less. Provision of proper ventilation systems is necessary if you use either space or central heating. It is also difficult to provide adequate ventilation with central heating while vents for space heating can be arranged easily. Therefore, many people prefer space heating to avoid the huge heating costs associated with central heating. Keep this comparison of space heating and central heating in mind, consider your preferences and choose the right option.

Know the Pros and Cons of Oil-filled Radiator Heaters

Planning to purchase an oil-filled radiator heater? Then, better understand their working and also their pros and cons. Oil-filled radiator heaters work by electricity, not by oil. Electricity passing through the device heats up the heating element and thereby, heats oil present inside. With rise in temperature, the heat from oil is transferred out of the device and is radiated throughout the room. Oil-filled radiators have their own pros and cons.


  • Oil-filled radiator heaters are available in various designs including wall-mount and mobile types. Wall-mount heaters can simply be hanged on wall at your desired location. Mobile oil-filled radiators may have wheels so that they can be easily moved from one room to the other.
  • Oil present in these heaters retains heat for a long time even after the power has been cut. So, though the heating device is switched off, the heated oil ensures heat and hence, you can still have warming effect upon the surrounding area.
  • They work well in smaller and well-insulated environments.
  • These heaters enable silent operation as they do not radiate heat through moving elements like fan.


  • Oil-filled radiator heaters do not provide instant warmth. They provide heat only after certain time lag. The oil in the heater takes some time to get heated up and hence, you need to wait to experience heat after switching on the device.
  • Maintenance of these heaters may be difficult. There may be chances of oil leakage which should be dealt carefully.
  • They may not be efficient to heat large rooms or areas.

Consider both pros and cons of these heaters and ensure that you follow proper maintenance to ensure effective functioning.