What Exactly Is an HVAC System And How Does It Work?

What Is an HVAC System and How Does It Work

Most homeowners understand what HVAC stands for (Heating, Ventilation, and Air conditioning). Most have a basic understanding of how the process works as well.

However, very few people are aware of everything that goes into a complete HVAC system.

It’s obvious. How often do you have to consider your air conditioner, furnace, or other HVAC equipment? Some have never had to buy a new system or perform anything other than routine maintenance on their existing equipment. When it comes time to make a new investment, whether it’s a new home or replacing old equipment, it’s important to know what’s what.

If you’ve progressed past that point and want to dig a bit deeper into HVAC topics other than this one, Earth Temp HVAC Blog is a great resource for residential HVAC information. However, if you’re still learning about the industry, this article will serve as a primer. By the end, you’ll have a solid understanding of HVAC equipment and processes, allowing you to have more productive conversations with your HVAC service provider.

What Exactly Is An HVAC System?

A heating, cooling, and ventilation system (HVAC) is the equipment, technology, and processes that are used to heat, cool, and ventilate a commercial or residential property. Air conditioners, heat pumps, furnaces, air handlers, ductwork, ventilation lines, filters, and other air quality products are examples of typical equipment included in this definition. Let’s dissect each of those for a better understanding.

HVAC Heating Equipment

Most homes will have a furnace to heat them. Furnaces come in a variety of shapes and sizes, and they can run on a variety of fuels, including the following:

  • Furnaces powered by natural gas
  • Electric heaters
  • Furnaces powered by propane
  • Furnaces that burn oil
  • Geothermal heat pumps

Natural gas furnaces are the most common these days, though electric furnaces are more popular in some parts of the country where winters are mild, gas prices are higher, or both.

Heating equipment typically includes a blower motor that circulates air throughout the home. The majority of homes have a forced-air system. This is where a blower distributes heat throughout the home via the duct work.

HVAC Ventilation Equipment

Ventilation refers to any of the systems that help to process and move air throughout your home, including your HVAC system. Ductwork, floor, wall, and ceiling vents, as well as other ventilation shafts such as chimney flues or PVC ventilation for indoor HVAC equipment, are typically included.

The ductwork in a home is intended to house the air that has been conditioned by the air conditioner or heated by the furnace. Inadequate ductwork can suffocate a system’s ability to heat or cool, or it can cause hot or cold spots where there isn’t enough ductwork to carry the air.

To vent excess heat from a system’s furnace, additional ventilation such as chimney flues and PVC vents are frequently required.

Vents are also used to distribute air on the outdoor air conditioning unit and throughout the home.

Many of these more advanced forms of ventilation will be absent from ductless HVAC systems. There will still be an indoor and outdoor unit, and the indoor units (or “heads”) will frequently be capable of heating and cooling (though some are cool-only). These, however, are typically for a single room or area, such as a finished basement or attic.

Many people consider natural ventilation in a home to be part of this category as well. The ability to create cross-flow from windows and doors can help keep your home comfortable.

HVAC Cooling Equipment

An air conditioner is typically included in an HVAC system (or several of them for commercial properties). Furthermore, heat pumps function similarly to air conditioners. A heat pump can both cool and heat a home.

Heat pumps are typically used in conjunction with electric furnaces, which supplement the heat pump’s ability to provide efficient heat. Traditionally, air conditioners are used in conjunction with gas furnaces.

How Does An HVAC System Work?

The main thing to remember is that HVAC equipment moves air. In general, a system exists to move warm air somewhere else, either into or out of the home. The heat is captured or created by a home’s air conditioner, heat pump, or furnace, and then moved by the blower and ductwork.

Below, we’ll take a look at each subsystem and discuss specific equipment and processes. It is critical to remember that a central air HVAC system is a living, breathing system that works as a whole. The heating system is not completely separated from the cooling system, and the parts and processes that enable both to operate properly regularly overlap.

Heating Your Home: What Is It and How Does It Work?

A furnace produces heat by either using electrical energy or by burning its fuel source. This fuel source is typically gas, but it can also be propane or oil.

When it comes to heating, a heat pump works a little differently. It absorbs heat from the outdoor unit and transfers it to the interior unit. It’s not so much generating heat as it is transferring it from one location to another.

Cooling Your Home: A Step-by-Step Reference

Air conditioners and heat pumps absorb heat from within a home and move it to the outdoor unit, where it is vented into the atmosphere, rather than producing cold air, as is commonly believed.

The refrigerant in a cooling system plays an important role in this. The refrigerant can be liquid or gaseous at different pressures. The HVAC system modulates the refrigerant pressures based on where it is. It can then absorb ambient heat and expel it once it reaches a different pressure.

Heat is systematically removed from the home by making the trip from inside to outside over and over, with the refrigerant’s pressure modulating accordingly.

As previously stated, a heat pump can absorb heat from the outside and transfer it inside. A heat pump will still be able to absorb heat from the outside in very cold temperatures (freezing temperatures and below), but at a less efficient rate. This is why, in most cases, a heat pump is paired with an electric furnace, which has compatible technology and supplements the heat pump’s heating capabilities.

How Does Home Ventilation Work?

The most obvious example is ductwork, which is directly connected to your heating and cooling system.

Excess heat can be discharged through a chimney flue or a vent stack as part of heating system ventilation. The efficiency of a furnace determines what percentage of its energy is used to heat your home. However, even in the most efficient heaters, which can achieve 95-97 percent efficiency, the remainder is vented.

Depending on the equipment, ventilation that exits on the side of a house rather than above it may be required. This is intended to prevent moisture condensation in the HVAC system, which can cause long-term damage.

Odds and Ends in HVAC

There are a few ancillary items we haven’t covered yet, as well as large components of your equipment that help to regulate its operation. Some of these are listed below, but this is not an exhaustive list of HVAC system equipment. Rather, the list is intended to give you an idea of what is included in a typical system, as well as a basic understanding of how they work.

Return Flight
An air return introduces fresh air into the main system via your filter.

Exhaust Ventilation
Some of these were mentioned earlier when we discussed chimney flues and vent stacks, but exhaust outlets are any areas where heat is vented from the home.

Furnaces are typically equipped with a 1-4 inch filter that traps particles that enter and pass through your system. These filters must be cleaned or replaced on a regular basis.

Components of Electrical Power
Each major piece of HVAC equipment must be able to communicate with other parts of the system. This is especially true if you have multi-speed equipment that automatically adjusts to temperature. All of this is managed by proper electrical circuitry and controls.

The thermostat serves as the system’s endpoint for user control and relays instructions throughout the system. Several electrical inputs in a thermostat may be required depending on how complex your system is and how much it needs to communicate with various devices.

The compressor is a critical component of any air conditioner or heat pump. It is responsible for regulating the pressure of the refrigerant. The compressor requires routine maintenance to avoid breakdowns because it works so hard when your system is in use.

Coils absorb and transfer moisture and heat, assisting in the regulation of refrigerant temperature. Depending on the efficiency of your unit, the size of the coils can vary significantly. ac or a heat pump It is responsible for regulating the pressure of the refrigerant. The compressor requires routine maintenance to avoid breakdowns because it works so hard when your system is in use.

Who Is Capable of Servicing HVAC Equipment?

Installing or servicing HVAC equipment necessarily involves years of training as well as state, local, and national certifications as required by your jurisdiction. While some simple tasks, such as filter changes, can be performed by a homeowner, repairs, part replacements, and full installations should always be handled by a qualified technician.

Plumbing, electrical work, metalwork, brazing (a type of welding), carpentry, and other skills are required to install and maintain HVAC equipment.

Furthermore, many of the installation and testing processes necessitate the use of specialized equipment that the average homeowner will not own or be trained to use.

Only the Beginning of Learning About Your System

While your system should be serviced by a licensed HVAC contractor, the more you know about it, the better chance you’ll have of selecting the best system, options, and accessories for your home.

You’ll also be better equipped to select the best HVAC technician to meet your comfort requirements.

What do you think?

Written by HVAC Contributor

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