A heat exchanger in HVAC system is a component that transfers heat between two fluid streams without the fluids mixing together through conduction. In HVAC system there are mainly two types of heat exchangers; Air-to-Air heat exchangers and Air-to-Water heat exchangers

The rate of heat consumption or heat transfer (British Thermal Units per hour (BTU/hr)) is typically measured in units of Power. It is important to consider when sizing HVAC equipment or designing heating systems to ensure the heating capacity matches the space or application requirements.

According to Fourier’s law, the rate of heat transfer (Q) between two bodies is directly proportional to the temperature difference (ΔT) between them.

The British Thermal Unit (BTU) is a unit of heat energy. One BTU is defined as the amount of heat energy required to raise the temperature of one pound (lb) of water by one degree Fahrenheit (°F) at a constant pressure.

The heat content of the substance is also known as the enthalpy (H).  It takes into account both the internal energy (kinetic energy of its particles (molecules, atoms) and the potential energy associated with their positions and interactions) and the work done by or on the substance. It is often expressed in units of energy, such as joules (J) or British Thermal Units (BTUs).

According to the inverse square law, the radiant heat energy spreads out evenly in all directions from its source. The intensity of the heat diminishes with the square of the distance traveled from the source.

The boiling point of a substance is the temperature at which its vapor pressure equals the atmospheric pressure or the pressure exerted on the liquid. If the pressure on the water is increased, its boiling point also increases which requires a higher temperature to reach the vapor pressure equal to the increased pressure.

Space heaters do heat the air in the surrounding environment. Space heaters are designed to generate heat and transfer it to the air in a room or enclosed space, thereby raising the temperature.

Latent heat is the heat energy required to change the state of a substance from one phase to another, such as from solid to liquid (fusion/melting), liquid to gas (vaporization/evaporation), or gas to liquid (condensation), at a constant temperature. During a phase change, the energy absorbed or released is used to break or form the intermolecular forces holding the particles together. This results in a change in the arrangement or motion of the particles, but not in their kinetic energy (temperature).

The term “boiler horsepower” is a unit of power used to measure the output capacity of boilers and steam generators.

On the Fahrenheit scale, absolute zero is approximately -459.67 degrees Fahrenheit (-273.15 degrees Celsius).

The Celsius scale (Kelvin) is based on the freezing and boiling points of water, where 0 degrees Celsius represents the freezing point and 100 degrees Celsius represents the boiling point at standard atmospheric pressure. To convert temperatures on the Celsius scale to the Kelvin scale, which is an absolute temperature scale, you need to add 273.15

The Celsius scale is based on the freezing and boiling points of water, where 0 degrees Celsius and 100 degrees Celsius respectively

Absolute zero is the lowest temperature on the Kelvin scale and is defined as 0 Kelvin (0 K). It represents the point at which all molecular motion theoretically ceases, and no further decrease in temperature is possible. Absolute zero serves as the reference point for temperature calculations because it is the point of minimum thermal energy.

Heat transfer can take place when temperature difference exist within same medium or between different media

At Absolute zero temperature on the Kelvin scale, all molecular motion theoretically ceases