Specifically: (Steam Boilers) An arrangement of pipes for heating feed water by waste heat in the gases passing to the chimney.

Utilizes waste heat by transferring heat from flue gases to warm incoming feedwater.

A heat exchanger that transfers heat from the gases of combustion to the Boiler Feedwater.

A ducting arrangement and automatic control system that allow a cooling supply fan system to supply outdoor air to reduce or eliminate the need for mechanical refrigeration during mild or cold weather.

A system that uses the maximum outside air for ventilation and free cooling, as long as dehumidification is not necessary.

In a chiller with a two-stage centrifugal compressor, the discharge from the first stage impeller and the inlet to the second stage impeller are at a pressure level approximately half way between the cooler pressure and condenser pressure. With this arrangement, an economizer may be used. This is a shell within which refrigerant liquid from the condenser drops down to the interstage pressure, flashing off some of the refrigerant which is drawn directly into the second stage impeller. This reduces the amount of refrigerant which has to be compressed by the first stage impeller, improving the refrigeration cycle efficiency.

One who, or that which, economizes.