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NORA Oilheat Technicians Manual

Oilheat Technicians Manual One-Pipe System (Hot Water): A hot water heating system in which one pipe serves both as a supply main and also as a return main. The heating units have separate supply and return connections to the same main. One-Pipe System (Steam): A steam heating system consisting of a main circuit in which the steam and condensate flow in the same pipe. There is but one connection to each heating unit, which must serve as both the supply and return. Over Head System: A heating system in which the supply main is above the heating units. Oxidizing Flame: A flame produced by the burning of a fuel with more than the amount of oxygen required for burning under stoichiometric conditions. Oxygen (O2): The lesser quantity of air that is necessary in the combustion of any fuel. When found in large quantity in flue gases, it is an indication of excess air being introduced to the unit. Panel Heating: A method of heating involving the installation of the heating units (pipe coils) within the wall, floor or ceiling of a room. Plenum Chamber: An air compartment maintained under pressure and connected to one or more distributing ducts. Pour Point: Lowest temperature at which fuel will flow. The ASTM standard for untreated No. 2 oil is 17°F. Primary Control: In an oil burner circuit, it is the control responsible for the proper sequencing and safety of the operation of the burner. It is often referred to as the cad cell relay, protectorelay, stack switch or master control. Pressure: The force-per-unit-area measured in pounds-persquare inch, inches of water or millimeters of mercury. Pressure Reducing Valve: A piece of equipment for changing the pressure of a gas or liquid from a higher pressure to a lower one. Pressuretrol: A pressure controller often used to identify the control used to limit the pressure in a steam system. Proportioning: Can be applied to the maintenance of the ratio between fuel and air supply throughout the operating range of the burner. Protectorelay: See “primary control.” Radiant Heating: A heating system in which the heating is by radiation only. Sometimes applied to a panel heating system. Radiation, Equivalent Direct: The amount of heating surface expressed in square feet which will deliver 240 Btu/HR for steam, and 150 BTU/HR for hot water systems operating at design conditions. Radiator: Heated and exposed to view, radiator transfers heat by radiation to objects “it can see” and by conduction to the surrounding air, which in turn is circulated by natural convection. Recirculation: A strong, swirling air pattern that recirculates combustion products for more complete mixing of fuel and air. Register: In heating and air conditioning, it refers to a grille for the distribution of air which most often contains a built-in damper or shutter. Relative Humidity: The amount of moisture in a given quantity of air compared with the maximum amount of moisture the same quantity of air could hold at the same temperature. It is expressed as a percentage. Relay: An electromechanical switching device that can be used as a remote control. Return Mains: The pipes which return the heating medium from the heating units to the source of heat supply. Reverse Return System: (Hot Water) A two-pipe hot water heating system in which the water from the several heating units is returned along paths, arranged so that all radiator circuits of the system are practically of equal length. Sensible Heat: Heat which only increases the temperature of objects as opposed to latent heat. Series Loop System: A hot water heating system in which a single pipe connects from the heating unit to the first distributing unit then on to the next distributing unit, continuing this way until it returns to the heating unit. All distributing units would then be connected in series. Solenoid: An electromagnetic coil that contains a movable plunger. Square Foot of Heating Surface: See “Radiation, equivalent direct.” Stack Switch: See “Primary control.” Stack Temperature: The stack (flue gas) temperature is the temperature of combustion gases leaving the appliance, and reflects the energy that did not transfer from the fuel to the heat exchanger. Static Pressure: The pressure necessary to overcome the frictional resistance to flow. In an oil burner, it will refer to Oilheat Technicians Manual—XI


NORA Oilheat Technicians Manual
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