Within cove.tool, there are many heating and cooling HVAC systems available to choose from that apply to residential projects. Below are some of the most common types of HVAC systems used and the corresponding options available on our platform.
Please note that on the platform, system types are named with the following scheme, allowing for quick and easy assignment of detailed design inputs:
'Air System w/ room units' + 'Heating System' + 'Cooling System'
Heating and Cooling Split Systems
The standard split system consists of two units –one outside, and the other inside– each doing heating and cooling exclusively. This setup is the most popular residential HVAC system today. Split systems can be configured in several ways to address the demands of the climate:
Furnace and air conditioner:
Gas furnaces range in efficiency from 80 percent (typical for warmer climates) to 98 percent (a more cost-effective choice in cold climates) and are located within the home. 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. When cooling is activated, the evaporator coil captures heat and sends it outside via the refrigerant circulating through the copper lines. Air conditioner models range in efficiency too; the warmer the climate is, the more beneficial it is to install an AC with a higher seasonal energy efficiency rating (SEER). The corresponding system type to select for this:
Single Zone, with Furnace and Direct Expansion
Air handler and heat pump:
Instead of two units supplying heating and cooling separately, this system uses a heat pump for both functions. These systems have varying efficiencies, depending on the climate and manufacturer. A heat pump is almost exactly like an air conditioner except that its operation can be reversed in cold weather. Because the heat pump provides heat, negating the need for a furnace, an air handler with a blower motor is used to circulate the air through the home instead.
To model this system on the platform start by selecting Single Zone, with Electric Resistance and Packaged DX. Next swap the Heating System COP to ~3, the exact performance will be based on the manufacturer of the unit.
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. Two-stage and modulating split systems optimize indoor climate control. The disadvantage is that traditional split systems require ductwork, so they are impractical where adding ductwork is too costly or impossible.
Ductless Mini-Split Systems
Ductless mini-split systems consist of an outside AC for cooling only or a heat pump for cooling and heating. Furnaces are not required in ductless split systems. The indoor component has a fan for dispersing conditioned air and can be installed on walls, the ceiling, or the floor.
It is typical that a mini-split system is connected to a heat pump and offers both heating & cooling abilities, which can be modeled as:
Natural Vent, with ASHP and Direct Expansion
In the case that the heating and cooling is decoupled, which is common in existing buildings with built-in heating infrastructure that later added AC units for cooling, choose from the following systems:
Natural Vent, with Gas Boiler and Direct Expansion
Natural Vent, with Electric Boiler and Direct Expansion
Natural Vent, with Electric Resistance and Direct Expansion
Typical types of decoupled heating are baseboard fin tube, radiator, and radiant floors. All of these can be modeled with the above three systems based on the primary heat source listed.
Pros and Cons
Ductless split systems are ideal for homes with no existing ductwork. One outside unit can provide treated air to as many as four indoor units, and each unit can be regulated with its own thermostat for precise, zoned climate control. The efficiency of ductless systems ranges from good to excellent, so they are a great option for reducing energy use and costs. The disadvantages of ductless split systems are that they aren’t suitable for extremely cold climates and they don’t offer the spectrum of options you get with standard split systems. They are also visible within the space.
A packaged system is manufactured with all the major components in one large cabinet. They are most popular in homes without basements. Packaged units are always installed outdoors. All packaged systems contain a blower to force treated air into the home and draw untreated air into the system. The method of treating the air varies with the type of packaged unit:
Single Zone, with Gas Boiler and Packaged DX
Single Zone, with Electric Boiler and Packaged DX
Single Zone, with Furnace and Packaged DX
Single Zone, with Electric Resistance and Packaged DX
Pros and Cons of Packaged Systems
Packaged systems are only used when traditional split systems are not an option. The advantage is that they aren't as noisy, since the mechanical components are located outside. The disadvantages are that package systems don’t offer as many options as standard and ductless split systems, and they are less efficient overall. Additionally, since all the components are outdoors and exposed to the elements, they tend to wear out faster than other HVAC systems and thus require more maintenance.