Electromagnetic radiation having wavelengths between that of violet light and x-rays.

A coal firing system that introduces the coal under the fire.

A heater with electric resistance, steam, or hot water heating elements to heat the air. Natural or forced draft units are designed for wall mounting.

Fractions which do not have the same denominator, i.e. 1/2 and 1/3

A device in a compressor for equalizing high and low side pressures when the compressor stops and for a brief period after it starts in order to decrease the starting load on the motor.

A system in which domestic water supply enters the building in the basement and travels through horizontal pipes.

The connection between the boiler and the stack.

An element of nature, symbol U, atomic number 92, used in the production of fuel rods for nuclear fission.