UL 307B-2009 pdf download – Gas-Burning Heating Appliances for Manufactured Homes and Recreational Vehicles.
2.2 Units of measurement 2.2.1 If a value for measurement is followed by a value in other units in parentheses, the second value may be only approximate. The first stated value is the requirement. 2.2.2 Unless indicated otherwise, all voltage and current values mentioned in this standard are rms. 2.3 Terminology 2.3.1 The term ″appliance″ as used in this standard refers to any heating appliance covered by this standard, such as a warm air central furnace, a wall furnace, a heating boiler, and a water heater. 3 Glossary 3.1 For the purpose of this standard, the following definitions apply. 3.2 AIR SHUTTER – An adjustable device for varying the size of the air inlet or inlets regulating primary or secondary air. 3.3 APPLIANCE FLUE – The flue passages within the appliance. 3.4 AUTOMATICALLY LIGHTED APPLIANCE – An appliance in which fuel to the main burner is intended to be turned on and ignited automatically. 3.5 BOILER – A closed vessel in which water or some other liquid is heated or steam is generated or superheated, under pressure or vacuum, by direct application of heat. 3.6 BOILER, LOW PRESSURE HOT WATER – A boiler that furnishes hot water at a pressure not exceeding 1 60 psig (1 1 03 kPa) and at a temperature not exceeding 250°F (1 21 °C). 3.7 BOILER, LOW PRESSURE STEAM – A boiler in which steam is generated at a pressure not exceeding 1 5 psig (1 03 kPa). 3.8 BURNER – A device for the final conveyance of fuel or a mixture of fuel and air to the combustion zone. a) Forced-Draft – (See Power Burner, (e)). b) Induced-Draft – A burner that depends on the draft induced by a fan beyond the appliance for its proper operation. c) Injection (Bunsen) Type – A burner employing the energy of a jet of gas to inject air for combustion into the burner and mix it with the gas.