Hertz refers to the unit of frequency used to measure the number of complete cycles of alternating current (AC) electricity that occur in one second. One hertz (Hz) equals one cycle per second. In HVAC systems, this term is commonly used when discussing the operation of motors, compressors, or variable frequency drives, which may adjust...

A single-stage furnace design that operates exclusively at its maximum capacity, meaning it always runs at 100% output whenever it’s on. Unlike modulating or two-stage furnaces, which can adjust their heating levels based on the home’s needs, a high fire only furnace does not have variable capacity and is either fully on or completely off....

A type of furnace or air handler commonly used in confined spaces like attics or crawl spaces. In a horizontal flow system, air is taken in from one side of the unit, passes through the heating or cooling components, and is then pushed out the other side to be distributed through the ductwork. The horizontal...

Heating Seasonal Performance Factor. This is a measure of how efficiently a heat pump provides heating over an entire heating season. It is calculated by dividing the total heating output (measured in BTUs) by the total electricity consumed (measured in watt-hours) during the same period. A higher HSPF rating indicates a more efficient heat pump....

A device used to add moisture to the air, increasing the humidity level in a space. Humidifiers are commonly used in homes, offices, or hospitals to alleviate dryness in the air, which can cause discomfort such as dry skin, irritated sinuses, or scratchy throats. They can come in various types, including evaporative, ultrasonic, and steam...

A humidistat is a device used in HVAC systems to measure and control the humidity levels in the air. It works by detecting the moisture level in the environment and signaling the system to increase or decrease humidity as needed. For example, it can turn a humidifier on when the air is too dry or...

Humidity refers to the amount of water vapor present in the air. It plays a big role in weather, comfort, and HVAC system performance. Higher humidity means more moisture in the air, while lower humidity means the air is drier. In HVAC systems, controlling humidity is important because it affects both how comfortable a space...

The amount (or mass) of water vapor present in a given volume of air, usually expressed in units such as grains of moisture per cubic foot or grams per cubic meter. It represents the actual quantity of water vapor in the air, regardless of temperature, and is an important factor in understanding indoor air quality...

The amount of moisture present in the air compared to the maximum amount of moisture the air can hold at a specific temperature, expressed as a percentage. For example, if the relative humidity is 50%, the air is holding half of the moisture it could hold at that temperature.

In summer, reducing the humidity in the air improves comfort by making the environment feel cooler and less sticky. Air conditioners and dehumidifiers are commonly used to lower humidity levels. Reducing summer humidity can also prevent odors, mildew, and mold growth, particularly in damp areas like basements. Additionally, lower humidity allows people to feel comfortable...