What is HVAC?

In this day and age of getting exactly what you want at the push of a button, consumers expect to be in complete comfort at all times.

That is exactly what an HVAC system provides. As an electrician, you will not only learn what HVAC is, but also how to install and maintain the entire systems.

HVAC stands for “Heating Ventilation Air Conditioning”. Although each of these elements produce entirely different effects, in many cases they have all been incorporated into one system to provide homes and buildings with “climate control”.

Climate control means that the atmosphere and temperature in a home or building stay steady, year-round. The entire home or building will feel warm and comfortable in all types of weather – never too hot or humid in the summer, and never too cold or dry in the winter.

The comfort of consumers is very important, but an HVAC system may be even more important in environments such as museums. The historical artifacts kept in these institutions are irreplaceable.

Any damage caused by heat, cold, humidity or poor air quality may be irreversible, which means a big piece of the history of our world could be lost forever.

Choosing the Right HVAC System

When choosing an HVAC system, it is very important to select one that is appropriate for the size of the area it will be servicing, to ensure the highest level of efficiency and comfort.

All of your training will give you the knowledge you need to install and maintain a heating, ventilating and air-conditioning system, but choosing the right size goes beyond that.

If you choose a system that is too large or too small, the end result will be an inefficient HVAC system that could waste energy, and cost the customer more money in the long run.

You cannot accurately determine the correct size of an HVAC system by square footage alone, since this will not take into consideration the design or energy efficiency of the building.

Another common mistake is simply replacing a broken or worn-out system with an identical capacity, newer unit. This doesn’t work because older homes were often equipped with over-sized heating systems, when a much smaller one should have been used.

Also, a house may have undergone significant improvements, such as new insulation, better weatherstripping, and new windows. All of these improvements make the house much more energy-efficient, reducing the need for an over-sized HVAC system.

What is HVAC? #1 Heating

Ancient Romans are often credited for inventing the first central heating system. They installed hypocausts, which were air duct systems within the walls and floors.

Using boilers, space heaters and furnaces for indoor heating often results in incomplete combustion. When this happens, combustible by-products such as carbon monoxide and formaldehyde emit through the vents causing serious health problems for the inhabitants.

Proper ventilation is very important to prevent these emissions from becoming hazardous.

What is HVAC? #2 Ventilation

Ventilation actively replaces the air in indoor spaces in order to control the temperature. Many ventilating systems also remove moisture, excess heat, odours, smoke, dust or carbon dioxide, and replenish the air with oxygen.

Fresh air from the outside is brought in and recirculated with air within the building. Proper ventilation is a vital factor in maintaining acceptable levels of air quality in buildings. Ventilating methods are usually forced or natural.

Forced or Mechanical Ventilation

Forced ventilation uses an air handler to control the quality of indoor air. Many contaminants, odors and excessive humidity can be eliminated by replacing or diluting the indoor air with fresh air from outside.

However, climates with extreme humidity levels require too much energy to adequately remove the excess moisture with this method.

Kitchens and bathrooms are routinely equipped with a mechanical exhaust fan to help control odours and remove excess humidity. The design of these systems must take into account the flow rate (fan speed and size of the exhaust) and the level of noise is produces. Many applications can use direct drive fans, which require much less maintenance.

Ceiling, table and floor fans also provide a form of mechanical ventilation. They circulate the indoor air and give the impression of reducing the temperature, but actually it is the evaporation of perspiration on the skin that makes you feel cooler.

Because hot air rises, rooms can be kept warmer during the winter by reversing the ceiling fan so that warm air will be forced downwards.

What is HVAC? #3 Air Conditioning

Air conditioning is the process of removing heat. This is achieved with a system of radiation, convection and heat pumps working together in a process known as the refrigeration cycle.

Conduction medias, called refrigerants such as (water, ice, air and chemicals) complete the refrigeration system.

There are four essential elements within the refrigeration cycle that create the cooling effect. The cycle begins as a gas. The gas is pumped up to a high temperature and pressure level with a compressor.

From there it goes into a heat exchanger (also known as a condenser or condensing coil) where energy (heat) is pushed outside. This process condenses the refrigerant to a liquid.

This liquid is then brought back indoors and passed through another heat exchanger (also known as the evaporator or evaporating coil). The flow of the liquid is controlled by a metering device, to ensure the proper pressure and rate are maintained.

The liquid absorbs energy from the indoor air as it evaporates, goes back into the compressor, and the cycle begins again.

In a central air system, there is a reversing valve that automatically or manually switches from producing heat in the winter to air-conditioning in the summer. These all-in-one systems are usually more efficient, and much more convenient for homeowners, as well as large facilities.

What is HVAC Summary

So, what is HVAC?

It is heating, ventilation and air-conditioning – everything a building needs to control the climate indoors.

This can mean a combination of several pieces of equipment, each performing its own job, or all-in-one systems that can be adjusted as the weather changes.