HVAC Systems Buying Guide of 2021: Which is the Best?
Fortunately, most of us get to enjoy year-round climate control at the touch of a button. Heating, ventilation, and air conditioning, commonly known as HVAC, is standard inside the “thermal envelope” of a structure, which is the space that is heated and cooled.
HVAC systems need to be replaced from time to time, but most of us don’t shop for them everyday.
Today, we will discuss what an HVAC system does, the different forms the system can take depending on the application, and discuss a few pros and cons of the most common forms.
What Is an HVAC System?
An HVAC system conditions the air inside the “thermal envelope” by heating, cooling, or just moving the air around the space.
In reality, this means any space that is insulated.
Today, it is very rare to find an inhabited structure without some form of HVAC in place.
An HVAC system will be the forced-air version, which just indicates the system physically pushes and pulls the air around, as opposed to a radiant heat source, like a fireplace.
How Does an HVAC System Work?
The answer will depend on the type of system in place and the method the system uses to condition the air.
In most residential homes, this system will be in the form of either a heat pump or furnace.
These systems are known as forced air systems because they incorporate a fan to both push conditioned air into a space and pull it from the space, in contrast to the traditional radiator or space heater we have all seen.
Forced air systems are much more efficient and, oddly, will often cost less to operate.
A furnace is essentially a centrally located HVAC system that provides heated air throughout a structure.
A furnace will typically use either an electrically heated coil or gas to warm the surrounding air, and with the help of a blower or air handler, circulate the warm air where needed.
It should be noted that furnaces, unlike a heat pump, do not directly provide air conditioning. In climates where a furnace is installed, many times the HVAC system will also include an air conditioner for use in the summer.
Undoubtedly, a heat pump is the most common form of HVAC used today.
Heat pumps can be designed as a single package unit, or in separate components called a split system.
A heat pump works by incorporating a condenser and evaporator coil to warm cold air from outdoors, or cool warm air from outside.
This system is very efficient, and will usually result in the lowest utility bill in a forced air system.
One downside to heat pumps is that they can be quite complex to install, so they tend to cost more initially. However, the energy savings acquired over time often makes a heat pump the most cost effective HVAC system available.
What Are the Different Types of HVAC Systems?
- Package Unit
- Split System
- Hybrid Split System (Gas and Electric)
- Mini-Split System (Ductless)
A package unit usually describes a heat pump with all of the working components in one large enclosure.
Most of us have seen a large gray or green box attached to the side of a home or business.
These package units are often the least expensive version of a heat pump because all of the components are inside the enclosure and do not require additional connections to the home.
However, package units are generally used on either one story buildings or in conjunction with a split system, because the ductwork must connect directly to the enclosure.
|Lower Materials Cost||In most cases, a package unit will be less expensive because nearly all of the working parts are packaged into one unit. This alleviates the additional work and expenses of connecting separate parts together. These units are also generally less expensive to manufacture because of their limited usability.|
|Lower Labor Cost||Labor charges will also be lower for the same reason. It is not uncommon for a package unit to be installed or swapped out in a matter of hours.|
|Durability||Package units tend to take a beating and keep going. These units are sturdy, easy to work on, and easily replaceable.|
|Limited Application||Package units are really only designed to be used on one story buildings. Multi-level structures will usually require a more customizable version, such as a split system.|
In contrast to a package system, a split system separates the condenser from the air handler, allowing the system to be custom designed for the application.
Split systems are typical on multiple story buildings, with the condenser residing outdoors and the air handler being located in a closet or attic space.
This design usually costs more initially because additional connections must be made between the condenser and air handler, as well as the normal connections to a thermostat.
These systems typically also require that the installer have more technical experience, because they will work with freon, a greenhouse gas.
|Very Adaptable||Split systems are very adaptable because the main components are separate and can be connected in any number of ways. These systems can be installed almost anywhere and have very few design limitations.|
|More Features||Split systems tend to have more elaborate design options as well. Upgrades, like increased efficiency, scroll compressors, etc. tend to be more commonly available on split systems.|
|Outdoor Components Are Smaller||Since in most applications only the condenser will be located outdoors, the system usually takes less space in the yard. This is particularly useful on small lots with very close property lines.|
|Higher Cost||Split systems are more expensive to install. Since the components must be connected together manually, the labor and expertise required to install a split system is typically higher. The added expense does not necessarily add more efficiency, but often exists simply because the home or lot design does not allow for a package unit.|
Hybrid Split System (Gas and Electric)
A hybrid split HVAC system uses both gas and electricity to heat and cool the air.
These hybrid systems are generally, along with geothermal systems, more expensive to install.
However, hybrid systems are often the most dependable HVAC systems available.
Hybrid HVAC systems are reliable and efficient, but they are usually the most complex forced air HVAC system to design and install.
|Highest Reliability and Convenience||Because a hybrid split system uses both electricity and gas, the system will generally be much more reliable. Some designs even function as a generator, powering the system even if electrical power is unavailable.|
|High Flexibility||Hybrid units are more complex to design and install, which allows the installer to adapt the system as needed for the application. Hybrid systems also tend to be installed in higher end homes with design complexities. This increased adaptability is sometimes the only way to build a functioning system when building designs require it.|
|Additional Maintenance||Hybrid systems will require considerably more maintenance, as essentially two systems must be cared for. This of course also adds to the cost of ownership over time, making a hybrid system one of the most expensive to own.|
Mini-Split System (Ductless)
Mini-split HVAC systems are designed to allow individual areas and rooms to be heated and cooled individually.
Ductless HVAC systems use small units (often wall mounted) that are individually located, but interconnected to a condenser/compressor located outdoors.
In this design, each room can be a different temperature, or each unit can be programmed the same.
Ductless systems are very scalable and although they can be expensive to install, are likely the most flexible HVAC system available.
|Most Control||Ductless HVAC systems offer the most zone control of any HVAC design. Because these units are physically located in each zone or room, they provide nearly complete control of the conditioned air.|
|Centrally Connected||Ductless systems are typically connected together via drain lines that prevent any condensation from doing damage. This same feature also eliminates one of the main drawbacks of window air conditioners, which is what to do with the condensation.|
|Cost||Ductless units are designed to be useful in any installation, but generally speaking these systems work best in smaller applications. Purchasing individual units is much less cost effective than installing one large unit, as the economy of scale is greatly diminished. As such, larger installations are usually better served by a typical ducted, forced air system. Ductless systems are often more about convenience than efficiency, so they work best in smaller, difficult to heat areas (such as a sunroom) that cannot be heated using other methods.|
Geothermal HVAC systems are relatively new to modern construction and take advantage of the consistent temperature of the ground.
For example, a standard heat pump may be required to raise the temperature of incoming air by twenty degrees or more, which can require an enormous amount of energy.
The larger the temperature difference between the incoming and outgoing air, the more energy is required.
Geothermal HVAC systems use a large area of ground into which pipes (known as PEX) are buried.
Since ground temperatures tend to remain consistent below the frost line, these pipes are never colder than the surrounding soil.
This means the system never has to work as hard as a standard system, because the incoming air is already relatively warm.
This makes the system very durable and efficient, but depending on the size of the system, the amount of ground required can be several acres.
|Extreme Efficiency||Geothermal HVAC systems generally offer the most return on investment. These systems are generally best for homeowners planning to stay in the home for many years.|
|Environmentally Friendly||Because geothermal systems are so efficient, they tend to be more environmentally friendly than comparable designs. Some estimates suggest that over the life of the system, it will use less than 50% of the energy required to operate a standard heat pump.|
|Land||Geothermal HVAC systems require larger lots than are typically found in subdivisions. These systems will generally require up to an acre per 1000 square feet of space to be heated, making them unsuitable for the majority of homes.|
|Initial Cost of Installation||Geothermal systems are often the most expensive HVAC system to install. Therefore, these systems will take the longest time to provide a return on the investment. Generally, the energy savings provided by a geothermal system will take about twice as long as a typical heat pump to offset the additional costs of installation. However, in the long run a geothermal system will cost less to operate.|
How Do I Know Which System Is Best For Me?
Package Unit Heat Pump
This question can be answered by determining the needs of the structure, the cost, and the services available.
Smaller, one story homes will often be best served by an electric, package style heat pump as these systems are typically less expensive to install.
Therefore, a package unit will often be found on smaller, single story structures with a relatively small yard.
Split System Heat Pump
If the home has multiple levels or needs a separate system for each floor, a split system is generally the best solution.
As described earlier, these systems are very customizable making them ideal for use in subdivisions with one or two story homes.
These systems also take up less space outdoors than a package system, making them very convenient to install on narrow building lots.
Hybrid Split System
Hybrid systems are most often found in larger, more elaborate homes with a larger budget.
This system is in effect, two systems sharing standard HVAC components, like ductwork.
As such, hybrid split systems are quite expensive to install initially.
In most installations, the lot will require a connection to public utilities, such as natural gas lines from the street, although liquid propane versions are available.
Mini-Split Ductless HVAC
As mentioned earlier, these systems provide the most flexibility, and in some situations, the lowest utility bill.
This is because unused rooms can be cordoned off if they are not being used.
These systems also address the common problems found with window air conditioners, such as collecting the water caused by condensation.
How Do I Find the Best HVAC System Installer?
Luckily, HVAC installation requires specialized training and licensing.
Licensed HVAC installers are also required to have their work inspected, so generally speaking, finding a qualified installer is easy.
However, because HVAC systems can be complex, even small discrepancies can cause the system to work inefficiently, or not at all.
The best HVAC system installers will have all of the aforementioned qualifications, and will also perform a load calculation.
This is essentially a worksheet that helps the installer calculate the precise system the structure needs.
This will include calculating the window sizes and their efficiency, how well the structure is insulated, and so on.
The installer can then take this information and match it as closely as possible to the systems available.
It is strongly recommended, therefore, to look for an installer that will spend the necessary time and effort to do a load calculation and apply it to find the best balance between cost-effective design and performance.