Most Common Types Of HVAC Systems
Heating, Ventilation and Air Conditioning (HVAC) systems are designed to help you keep your home at a comfortable temperature all-year round regardless of climate. HVAC systems are available in a wide variety of configurations: some are better suited for offices or homes with little space, while others utilize the heat of the earth to control the temperature indoors.
Installing a HVAC system is often a huge investment for homeowners, and even though HVAC systems are widely used, many people find the process of choosing the best system for them very confusing. This article is here to help simplify the process. In it we break down the most common types of HVAC systems, explain how they work, and examine their pros and cons. We’ll also uncover the meaning behind some frequently used HVAC jargon so you can feel more confident you’re making the best choice for your home.
Split HVAC Systems
By far the most common type of system, split HVAC consists of two main systems: one which heats your home, and another which cools your home. They often have one indoor unit, which can be installed in your garage, crawl space, basement or attic, and an outdoor unit, which is usually placed onto a level cement foundation outside your property. This is commonly referred to as an “AC pad”.
The central air unit will use a combination of refrigerant fluid, air compressors, and evaporator coils to reduce air temperature. Hot air within your home is expelled using a fan. Like most home heating systems, this process is managed using a central control thermostat located within the home. Split HVAC systems can be set up in many different ways. Depending upon the climate in your state, your split HVAC system can be a combination of heat pumps, furnaces, air handlers and air conditioners to meet your individual needs. For this reason, split HVAC systems are considered to be the most flexible option.
Split HVAC systems are usually the most affordable choice for homeowners if you have a ducting system already in place that needs replacing or upgrading, but they can become quite expensive if you need to get ductwork installed.
Hybrid Split System
Hybrid split HVAC systems are very similar to standard splits systems, but they differ in the way they are powered. Hybrid split HVAC systems use a “hybrid electric heater”, which enables the homeowner to use either electric or gas to power their HVAC system. As a result, though hybrid split systems are controlled by a centralized thermostat and require ductwork before installation similar to other HVAC systems, they also come with the benefit of often being more energy efficient to run.
In terms of pros and cons, hybrid HVAC systems are usually more expensive to install than standard split HVAC systems. If you have the funds to invest in a hybrid system, though, you will make your money back in energy bill savings in the long run. Many users claim to have recovered their initial installation costs within three to five years. Furthermore, using an environmentally friendly hybrid split HVAC system may mean that your household qualifies for a tax credit from the government. You can find out whether or not this applies to you by contacting your utility company.
Ductless Split Systems
As their names suggests, ductless split HVAC systems do not require ducting to be installed. Instead, these systems utilize multiple units within each room that the homeowners wishes to have control over the temperature. Ductless split HVAC systems are generally very efficient and able to reduce energy usage and energy bills, although they are not as energy efficient as hybrid systems.
Each of these units are mounted onto the walls and connect to a compressor outside the property. This makes them a convenient, economical and easy-to-install option if you do not have any ducting in your home. A single outside unit is capable of providing treated air to up to four units inside the home. Each of these indoor units comes with its own thermostat for individual climate control. Therefore, ductless split systems are particularly useful if you have a few rooms which you spend most of your time in, or if you need to heat/cool a new extension like a garage or a workshop. Ductless split systems are also a fantastic option for those who prefer independent temperature control in each room.
Packaged HVAC systems contain all the HVAC components – a condenser, compressor, furnace, coils and evaporator – within one unit. These HVAC systems are usually located on the roof of the property and ducted inside but may also be placed near the home foundations. They have a thermostat located within the building for control of the system.
Packaged systems are commonly used in commercial buildings, such as offices, as a space-saving alternative to standard split HVAC systems. They are a good choice of quiet air conditioner when compared to some split systems, as all of the mechanics and components are located outside the home. There are, however, some negative points to consider regarding packaged HVAC systems. For example, they tend to have more limited design options than split HVAC systems and they typically have a shorter working life due to the wear and tear of being exposed to the elements all year around.
Geothermal HVAC Systems
Geothermal HVAC systems utilize the heat underneath the ground. The temperature deep in the earth remains the same, even if you live in a region with an extremely hot or cold climate. Geothermal HVAC systems use an electronically powered heat pump to cycle fluid through a series of underground pipes for heat exchange. Geothermal heat pumps are highly efficient and can also be easily used to cool your property. In cooling mode, the heat which has been extracted from your home is released into the ground, which acts as a ‘heat sink’. The heat is absorbed into the cooler sections of the earth, then cool air is cycled back up into the home.
This method of conditioning the air in your property is highly energy efficient, environmentally friendly, and can significantly reduce household bills. Unfortunately, the initial cost of installing geothermal HVAC systems is high – sometimes as much as $20,000 – although you will get your investment back in energy savings within 10 years.
Understanding HVAC System Components
When deciding upon an HVAC system for your home, the technical language may become confusing. In this section, we break down the jargon surrounding HVAC systems:
Central Air Conditioners
Central air conditioning systems use a network of connected ducts to circulate cooled air around your home. Those which have inside and outside units, known as ‘split systems’, are the most widely used. Refrigerant fluid is circulated between evaporator coils and a condenser to cool the air that moves over these coils. This cooled air is then blown out into the room via a motorized fan.
Heat pumps are a slightly different variation of central air conditioners. Unlike air conditioners, heat pumps are able to both heat and cool air to be distributed into the home. In the summer, hot air is removed and ejected outside; during winter months, heat is extracted from the outside air or beneath the ground to be circulated into the home. The air and the ground outside always retains some heat, even when it feels very cold. Therefore, heat pumps are still able to heat your home from the warmth in the air or ground outdoors during the winter months. This process can also be reversed to cool your home when required.
Heat pumps transfer heat by cycling a refrigerant fluid through evaporation and condensation. The compressor pumps the fluid across two heat exchanging coils. In one of these coils, the refrigerant is evaporated under pressure and in the process absorbs heat from the space around it. Once heated, this refrigerant is then compressed before it reaches the next coil and condensed. As it condenses, the heat is released.
Furnaces usually use electric resistance heat strips or gas combustion, combined with a blower, to create heat and distribute it around your home. In some cases, furnaces may also be fitted with central air conditioners so that they also function as a cooling system when the climate is warmer.
A thermostat is the control panel for the HVAC system, and they work by monitoring the ambient temperature of the property and triggering the HVAC system once the temperature drops below, or rises above, the comfortable temperature set by the occupant. They are usually mounted on the wall in a central, easily accessible area of the home. Some thermostats are pre-programmed, but users have the option of manual controls too if required.
The evaporator coil makes up part of the refrigerant cooling system that works to absorb heat from the air. They are often U-shaped, made from steel, copper, or aluminum and attach to a panel close to the fan. To cool the air, the condensing unit and compressor move refrigerant through the evaporator coil which then expands and cools as it does so. This reduced temperature absorbs heat and renders the air that moves over the coil much cooler and more comfortable before it is released into your home.
Choosing the right HVAC system will result in a more comfortable home all year long. As we have seen, there are many different configurations available, all of which have their own benefits, drawbacks, and individual requirements. Understanding how each system works and its individual limitations is crucial when deciding which HVAC system is right for you.
In general terms, a split HVAC system is often the best choice for many homeowners. These are the most common and come with the flexibility to be set up in numerous ways to suit individual needs. If, however, your home lacks ducting, requires additional heating/cooling in specific areas or greater flexibility to create different temperatures in each room, a ductless split system might be the best option.
Packaged HVAC systems are not generally used unless split HVAC is incompatible, and while geothermal is a fantastic eco-friendly choice, the initial outlay costs are usually out of reach for most people. No matter what HVAC system you choose, you should have it installed by a registered professional with a solid reputation and keep up with annual maintenance visits to ensure your HVAC system continues to work efficiently for years to come.