Pilot light

Pilot light

A pilot light is a small gas flame, usually natural gas or liquefied petroleum gas, which is kept alight in order to serve as an ignition source for a more powerful gas burner.


Common applications include household water heaters, central heating systems, flame throwers, and hot air balloons. While most commercial kitchens still rely on pilot lights for burners, ovens, and grills, current residential systems typically use an electrical ignition.

afety Protection

In natural gas furnaces, water heaters, and room heating systems, a safety cut-out is usually included such that if the pilot light goes out the gas supply to the pilot and heating system is shut off by an electrically operated valve. This cut-out usually detects the pilot light in one of three ways:
# Sometimes a mercury filled sensor is used to detect the heat of the pilot light. Contraction of the mercury results in sufficient pressure to operate an electrical switch that interrupts the flow of electricity and shuts off the gas valve when the pilot light goes out.
# Sometimes a photoresistor is used to detect the light from the pilot lamp. Electrical circuitry connected to the photo-cell provides a current sufficient to keep the gas valve open all the time the pilot light is still burning.
# Use of a pilot generator or a thermocouple in the flame provides heating appliance safety as it generates enough electrical current from the burning flame to hold the gas valve open. If the pilot light goes out, the pilot generator cools off and the current stops, closing the gas valve.

The above methods are examples of the use of "fail-safe" safety protection.

Energy waste

In domestic heating systems with pilot lights it has been estimated that on average half the total energy usage is from the pilot light, each pilot light using from 240–500 W of gas (8–16 GJ/year). [http://web.archive.org/web/20041126084954/http://homeenergy.org/archive/hem.dis.anl.gov/eehem/97/970103.html] [http://homeenergy.org/archive/hem.dis.anl.gov/eehem/97/970302.html] [http://www.clarkpublicutilities.com/Residential/TheEnergyAdviser/Archives2002/2-02-1] That said, the heat from a pilot light in many appliances (furnaces, space heaters, hot water heaters) is generally released in the same chamber as the primary burner. The heat energy provided by the pilot light in these types of devices provides a minimal amount of heat to the device; the gas burned is not "wasted" (unless it is summer), since it contributes to the purpose of the device.

Modern alternatives

An alternative to the pilot light is a system that provides a high voltage electrical arc or “spark” between two electrodes close to the gas flow from the burner that is to be lit. Fail-safe design for such a system requires the burner flame to be detected by passing an electric current through the flame, which is “received” by a control box, whilst the flame is established there will be a flow of electrons through the flame so the control box keeps the appliance working, should the flame extinguish, the electron flow will be broken so causing the control box to shut down the appliance.

A red-hot surface can also be used to provide ignition. Such igniters are often made of silicon carbide, silicon nitride, or another material that is durable under prolonged exposure to extreme heat. Hot-surface igniters are commonly used in cooking ovens and broilers.

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Look at other dictionaries:

  • Pilot light — Pilot lamp Pilot lamp or Pilot light Pilot light (Elec.) 1. A small incandescent telltale lamp on a dynamo or battery circuit to show approximately by its brightness the voltage of the current. [Webster 1913 Suppl.] 2. a small light on an… …   The Collaborative International Dictionary of English

  • pilot light — ► NOUN 1) a small gas burner kept alight permanently to light a larger burner when needed. 2) an electric indicator light or control light …   English terms dictionary

  • pilot light — n. 1. a small gas burner which is kept burning for use in lighting a main burner when needed: also pilot burner 2. PILOT LAMP …   English World dictionary

  • pilot light — pilot lights N COUNT A pilot light is a small gas flame in a cooker, stove, boiler, or fire. It burns all the time and lights the main large flame when the gas is turned fully on …   English dictionary

  • Pilot light — Pi lot light , n. a small gas flame kept burning continuously on a stove, water heater, or other gas burning device, so as to allow immediate ignition of the main flame when the gas flow is turned on. [PJC] …   The Collaborative International Dictionary of English

  • pilot light — pilot ,light noun count 1. ) a small flame that burns continuously, used for lighting something such as a gas oven, STOVE, or FURNACE 2. ) a small light on a piece of electrical equipment that shows when the equipment is switched on …   Usage of the words and phrases in modern English

  • pilot light — n a small gas flame that burns all the time and is used for lighting larger gas burners …   Dictionary of contemporary English

  • pilot light — noun 1. small auxiliary gas burner that provides a flame to ignite a larger gas burner (Freq. 1) • Syn: ↑pilot burner, ↑pilot • Hypernyms: ↑gas burner, ↑gas jet 2. indicator consisting of a light to indicate whether power is on or a motor is in… …   Useful english dictionary

  • pilot light — UK / US noun [countable] Word forms pilot light : singular pilot light plural pilot lights 1) a small flame that burns continuously, used for lighting something such as a gas oven, cooker, or boiler 2) a small light on a piece of electrical… …   English dictionary

  • pilot light — /ˈpaɪlət laɪt/ (say puyluht luyt) noun 1. a small light kept burning continuously, as beside a large gas burner, to relight a main light whenever desired. 2. → pilot lamp. Also, pilot burner …  

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