Heat transfer that uses electromagnetic waves that travel in straight lines.

Panels that are embedded in the surfaces of the walls, ceilings and floors of a space for the purpose of heating. They may be electrically or hydronically heated.

An arrangement of tubes that absorb radiant heat from the furnace flame and transfers it to saturated steam.

Energy transmitted by wave motion without the need of intervening matter, i.e. Light waves.

The decay of an unstable atomic nucleus or isotope.

Random Access Memory, a type of computer memory that can be accessed for both reading and writing, as opposed to ROM (Read Only Memory).

The absolute temperature of the imperial system with graduations beginning at absolute zero. i.e. F + 460° = °R.

The amount of fuel being burned in the furnace per unit of time.

Untreated water.

Whenever a force acts on a body there is an equal and opposite reaction to the force produced by the body. A reaction is a force (Newton’s) that is equal to, and acts in an opposite direction to, the force. Examples of reactions are the ground supporting you by pushing back up or a rifle hitting your shoulder when it is fired.

A type of turbine that uses the reaction principle to convert heat energy into mechanical energy.

Refer to Liquid Receiver.

A compressor in which each compressing element consists of a piston moving back and forth in a cylinder.

The return air passed through a conditioner before being returned to the conditioned space.

A device that provides continuous records of measured variables with respect to time.