Page 350

NORA Oilheat Technicians Manual

Glossary Oilheat Technicians Manual the pressure within the burner tube as developed by the fan. In an air distribution system, it refers to the pressure necessary to overcome the total resistance created by the duct work. Steady State Efficiency: A measure of the carbon dioxide in the flue gases, expressed as a percentage, to determine the level of completion of the chemical reaction during combustion taken at “steady state” conditions, meaning there is no further change in the reaction process. Steam: Water vapor found when water has been heated to a boiling point, corresponding to the pressure it is under. Stoichiometric: Describes a condition in which the reactants of a chemical reaction are present in the exact quantities, as predetermined for the chemical equation of the reaction. It describes perfect combustion when the reactants are fuel and oxygen. Sulfur Dioxide (SO2): It is present in small quantities in fuel oil. It is the product of the combustion of sulfur. Supply Mains: The pipes through which the heating medium flows from the boiler, or source of supply, to the run-outs and risers leading to the heating units. Therm: A quantity of heat equal to 100,000 Btus. Thermistor: A resistor that is used to compensate for temperature variations in a circuit. Thermocouple: A junction of two dissimilar metals that produces a voltage when heated. Thermostat: An instrument which responds to changes in temperature and which directly or indirectly controls the room temperature. Transformer: A device composed of two or more coils, linked by magnetic lines of force. In transferring energy from one source to another, it can increase or decrease voltage. Two-Pipe System (Steam or water): A heating system in which one pipe is used for the supply main and another for the return main. The essential feature of a two-pipe system is that each heating unit receives a direct supply of the heating medium which cannot have served a preceding heating unit. Up-Feed System (Hot Water or Steam): A heating system in which the supply mains are below the level of the heating units which they serve. Vacuum Heating System (Steam): A two-pipe heating system equipped with the necessary accessory apparatus to permit the pressure in the system to go below atmospheric pressure. Vapor Heating System (Steam): A two-pipe heating system which operates at pressures at or near atmospheric and which returns the condensate to the boiler or receiver by gravity. Ventilation: Air circulated through a room for ventilating purposes. It may be mechanically circulated with a blower system or it may be natural circulation through an open window, etc. Vent Valve (Steam): A device for permitting air to be forced out of a heating unit or pipe and which closes against steam. Vent Valve (Water): A device permitting air to be forced out of a pipe or heating unit, but which closes against water. Viscosity: The measure of a liquid’s resistance to flow, generally measured in terms of Saybolt Universal or Saybolt Furol Seconds. Volt: The unit of electrical potential. Voltmeter: An instrument designed to measure a difference in electrical potential, in volts. Warm Air Heating System: A warm air heating plant consists of a heating unit (fuel burning furnace) enclosed in a casing, from which the heated air is distributed to the various rooms of building through ducts. If the motive heat producing flow depends on the difference in weight between the heated air leaving the casing and the cooler air entering the bottom of the casing, it is termed a gravity system. If a fan is used to produce circulation and the system is designed especially for fan circulation, it is termed a forced warm air system. Watt: The unit of electrical power. Wattmeter: An instrument for measuring electrical power in watts. Wet Return (Steam): That part of a return main of a steam heating system which is completely filled with water or condensation. XII—Oilheat Technicians Manual


NORA Oilheat Technicians Manual
To see the actual publication please follow the link above