Delta T refers to the difference in temperature between two points in an HVAC system. It is denoted by the symbol "△T" and is commonly used by technicians to evaluate how effectively the system is heating or cooling. For example, in an air conditioning system, Delta T might measure the difference between the air entering...

The U.S. Department of Energy (DOE) is a federal agency that oversees energy policy and promotes energy efficiency and innovation. In the HVAC industry, it plays a critical role in setting and enforcing minimum energy efficiency standards for heating, cooling, and ventilation equipment manufactured and sold in the U.S. These standards aim to reduce energy...

A desuperheater is a device used in HVAC systems to recover excess heat from the hot refrigerant gases leaving a compressor. This recovered heat is then used to heat water, typically for domestic or industrial use. By utilizing this waste heat, a desuperheater improves the overall efficiency of the system, reducing energy consumption and providing...

A diffuser is an HVAC component, typically a grille or panel, installed over an air supply duct. It is designed with adjustable or fixed vanes to evenly distribute the airflow from the duct into the room. The diffuser helps control the direction, pattern, and spread of the air, ensuring it circulates effectively and enhances comfort...

The Department of Energy (DOE) is a federal government agency in the United States responsible for addressing matters related to energy production, distribution, regulation, and conservation. In the HVAC industry, the DOE plays a critical role by setting energy efficiency standards for heating, ventilation, and air conditioning equipment, ensuring these systems consume less energy and...

A downflow furnace is a type of heating system designed to take in return air at the top and release the heated air downward through the bottom. This design is commonly used in homes where the ductwork is located below the furnace, such as in homes with basements or slab foundations. The airflow direction is...

A drain line is a pipe in an HVAC system that removes condensation produced by the evaporator coil as it cools the air. If this line becomes clogged, it can cause water to overflow, potentially damaging surrounding areas, such as ceilings if the air handler is located in the attic. Preventing clogs through routine maintenance...

A drain pan, also known as a condensate pan, is a component of an HVAC system designed to collect water that forms as condensation when warm, humid air comes into contact with the cold surfaces of the indoor evaporator coil. This condensed water drips into the drain pan and is then directed away from the...

A drier is a device used in refrigeration and HVAC systems to remove moisture and contaminants from the refrigerant. It contains a desiccant material that absorbs water and filters out debris to prevent damage to system components, such as the compressor and expansion valve, and to ensure optimal performance and efficiency of the system.

Dry bulb temperature is the temperature of the air measured by a regular thermometer that is not affected by the moisture in the air. It represents the actual air temperature and is typically used as a baseline for many HVAC calculations.