What coils are used in HVAC?

There are several types of coils that are commonly used in HVAC (heating, ventilation, and air conditioning) systems, depending on the specific application and the system design. 

Here are some of the most common types of coils used in HVAC:

Chilled Water Coils: These coils are used in larger commercial or industrial HVAC systems and are connected to a central chiller plant that cools water to a low temperature. The chilled water flows through the coil, which absorbs heat from the air passing over it, resulting in cooled and dehumidified air being supplied to the building.

Direct Expansion (DX) Coils: These coils are often used in smaller HVAC systems, such as those found in residential or small commercial buildings. This type of coil uses a refrigerant, which is circulated through the coil and evaporates as it absorbs heat from the air passing over it. The cooled and dehumidified air is then supplied to the building.

Hot Water Coils: These coils are used for heating and are typically connected to a boiler or other heating source. Hot water flows through the coil, which heats the air passing over it, resulting in warm air being supplied to the building.

Steam Coils: These coils are used for humidification and are typically connected to a steam boiler. Steam flows through the coil, which adds moisture to the air passing over it, resulting in humidified air being supplied to the building.

The specific type of coil used in an HVAC system will depend on factors such as the size of the system, the desired indoor comfort levels, and the availability and cost of energy sources.