Currently, there are four different models of HVAC systems, but they are available in many different sizes.
1- Split Systems
An HVAC split system is for homes that have space for large indoor cabinets. The split system model holds the condenser and compressor in an outdoor cabinet. Another indoor cabinet will hold the evaporator coil, and an air handler sends the cool air through the duct system. A line set (a copper tube that connects both the indoor and outdoor components) moves cold air to the house. Unlike packed systems, which we will discuss more later, split systems offer more energy efficiency and lower operating costs.
The tricky part with a split system is the installation. It can often be quite complex and must be
professionally installed by an expert. It’s also difficult to mix and match components of a split system.
They normally require everything to be from the same manufacturer if you want the system to work at its
best, and qualify for warranties, and rebates from utilities.
Normally, a split system HVAC unit will have:
- An outdoor component, or a condenser, such as an air conditioner or a heat pump.
- An indoor component that consists of an evaporator coil or fan, along with furnaces that convert refrigerant and help circulate air.
- A system of ducts that circulate air from the HVAC unit throughout your home or building.
- A thermostat — either programmable or non-programmable — that manages the system
- Accessories that help improve the quality, and comfort, of the indoor air such as purifiers, air cleaners, UV lamps, or humidifiers.
Split systems can be configured in several ways to address the demands of your climate:
- Furnace and air conditioner: Most systems employ a gas furnace (only 5 percent have an oil furnace). Gas furnaces range in efficiency from 80 percent (better for warm climates) to 98 percent (a more cost-effective choice in very cold climates). The air conditioner’s condensing unit is installed outside. A key component of the system is the evaporator coil, which is typically installed inside the cabinet of the furnace. The evaporator coil captures heat and sends it outside via the refrigerant circulating through copper lines.
- Air handler and heat pump: Heat pump split systems are common in warm regions where freezing temperatures are rare. Instead of an air conditioner for cooling and a furnace for heating, the system uses a heat pump for both functions. A range of efficiency levels is available. A heat pump is almost exactly like an air conditioner except that its operation can be reversed in cold weather. Because the heat pump delivers heat, an air handler with a blower motor is used in place of a furnace.
- Furnace and heat pump: Split systems with two sources of heat are called dual fuel or hybrid heat systems. They are ideal for very cold climates. The heat pump supplies heat in moderate cold. The system automatically switches to the gas furnace when temperatures drop below freezing and heat pumps become ineffective. The most cost-effective hybrid split systems will include the following:
- A heat pump to cool or heat refrigerant
- An evaporator coil and furnaces that work to convert refrigerant and circulate air
- A furnace either oil or gas
- Ducts to take the warm or cool air throughout your home or your building
- Accessories to improve indoor air quality
Pros and Cons of Split Systems
Split systems offer the greatest range of options. They are the most affordable HVAC system type,
especially for replacement systems. The new components can be installed with no or minor modifications to the home’s existing ductwork. Two-stage and modulating split systems optimize indoor climate control. The disadvantages are that traditional split systems require ductwork, so they are impractical where adding ductwork is too costly or impossible.
2- Duct-Free or Ductless Air Conditioning and Heating Systems
This is a great ultra-efficient HVAC. It is most popular use is in areas or places where conventional systems of ducts cannot be used. They are also ideal complements to use with HVAC systems that do use ducts if you need a supplement or to expand your air conditioning and heating area. We use them to dehumidify and heat basements, to heat and cool the room over the garage, or to condition any hard-to-cool or heat part of the office or home.
These systems normally consist of an indoor wall-mounted unit connected to an outside compressor. Unlike duct systems, these units only need a small hole drilled in the wall. This makes them much less vulnerable to possible security problems or air leakage. They are also relatively quiet.
In most homes, about 20% of energy is wasted with a ducted system, so right away, using a ductless system makes your system more efficient. Also, since ductless systems use inverter-driven compressors, they react much better to the actual needs of the system and don’t shut off completely like a traditional HVAC unit, which can expend a lot of energy every time it starts up again. It also dehumidifies so you can feel much more comfortable at a higher temperature.
Duct-free systems contain the following components:
- An air conditioner or heat pump to cool or heat refrigerant
- A compact fan coil
- Wires and tubes to connect refrigerant from the outdoor unit to the fan coil
- A thermostat to manage the system
- Indoor air quality accessories to improve air quality before it is circulated throughout the home or building
Ductless mini-split air conditioning systems are known to provide the following benefits to your home or commercial space:
- Excellent Efficiency – Ductless ACs boast high-efficiency ratings, and they utilize smaller equipment allowing them to use less energy
- Ideal Installation – Because they don’t require ductwork, the installation is quicker. This decreases any “downtime” in your comfort!
- Awesome Air Quality – Each indoor unit filters out the air, helping to remove excess dust from the home. The lack of ductwork also reduces the amount of dust being circulated
- Minimal Maintenance – Ductwork needs to be cleaned regularly, and sometimes needs to be repaired. Although filters still need to be changed for ductless ACs, there is no ductwork to clean or repair
Overall a ductless mini-split AC system saves homeowners money thanks to the efficiency and smaller size of the system!
3- Packed System for Heating and Air Conditioning
The packaged HVAC unit houses all parts of the system in one metal cabinet. The evaporator coil,
condenser and compressor are all housed together to save space from being used inside.
Often, the cabinet is either placed on a home or building’s ceiling, or on a cement slab outside the home.
Specially-made ductwork connects the outdoor cabinet to all the rooms in the home. Though the cabinet is outdoors, the actual functions of a packaged central air system are controlled indoors.
Some packaged central air systems will also include a natural gas furnace or electric heating coils as well.
In short, a packaged HVAC unit comprises everything involved in a central air system in one unit placed
outside the home. Homes with little indoor space to house these systems (or those lacking underground spaces) will have a packaged unit.
They can cool or heat an entire home or a one-room unit. They are also often the best choice to heat or cool a very large space. Packed systems are much easier to install than split systems. If your home or your office is too small for an air handler component to be installed inside, then a packed system is a real space saver. They can sit on your roof or on the side of your building or home. A technician can install it in a day or two, while a split system takes about a week. It’s also easier for the technician to maintain since all the components are in one place.
The disadvantage of a packed system is that they are outside and exposed to extreme weather. It is easier to damage. While packed systems are built to resist bad weather, they are not foolproof. You also need to make sure they are free of any leaves, standing water, or debris. If the system is located on your roof, this adds an additional element of difficulty.
A packaged system will contain:
- The heat pump, or gas furnace, air conditioner and fan coil, and evaporator reside in one unit
- An interface/thermostat on the front of the unit will allow you to control the system
- Optional indoor air quality accessories
The method of treating the air varies with the type of packaged unit:
- Gas/electric: A gas furnace and an air conditioner
- Heat pump: One unit providing both heating and cooling
- Hybrid: A heat pump for most of the heating and all the cooling, and a gas furnace for heating when temperatures are below freezing
4- Geothermal HVAC Systems
Geothermal systems use the stable temperatures of the earth to facilitate heating and cooling. Water, often containing refrigerant, is circulated through pipes installed in water or the ground to collect or shed heat.
The constantly moderate temperatures of the ground facilitate efficient dumping of heat in summer and collecting of heat in winter.
Pros and Cons of Geothermal Systems
Geothermal HVAC systems offer efficiency levels up to four times that of traditional systems. The
reductions in energy use and cost are significant. The main concern about geothermal HVAC systems is
their price, which can range from two to five times that of other systems.
| # | Type | Components | Places |
| 1 | Split Systems | – Outdoor component, or a condenser, such as an air conditioner or a heat pump – Indoor component: consists of an evaporator coil or fan, along with furnaces that convert refrigerant and help circulate air – A system of ducts – A thermostat – Accessories | |
| 2 | Duct-Free or Ductless Systems | – An air conditioner or heat pump to cool or heat refrigerant. – A compact fan coil. – Wires and tubes to connect refrigerant from the outdoor unit to the fan coil. – A thermostat to manage the system. – Indoor air quality accessories to improve air quality before it is circulated throughout the home or building. | Where ducts cannot be used |
| 3 | Packed System | – The heat pump, or gas furnace, air conditioner, and fan coil and evaporator reside in one unit – An interface/thermostat on the front of the unit that will allow you to control the system. – Optional indoor air quality accessories. | Buildings under 10 stories |
| 4 | Geothermal HVAC Systems |
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