Enthalpy is easy. It's just a state function that depends only on the prevailing equilibrium state identified by the system's internal energy, pressure, and volume. It is an extensive quantity. Simple. Like most things, the scientific definition is as clear as mud. In HVAC/R, we use enthalpy measurement to come up with the total heat […]

There is a common belief in the trade that the higher the subcooling, the better the system efficiency because lower liquid line temperature means less flash gas. This statement is only partially true and can lead to some confusion among techs. Subcooling is a temperature decrease below the condensing temperature of the refrigerant that occurs […]

There was a story that came out recently based on an ASHRAE study performed by David Yuill from the University of Nebraska. The study appeared to indicate that condenser coil cleanliness makes no difference on system performance and efficiency. Those of us who have worked in the field know that coil cleaning matters because most […]