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Halogen Lamp

Incandescent lamp with halogen gas fill and a quartz glass capsule. The quartz capsule requires a separate glass shield or enclosure. Due to the halogen cycle, halogen lamps operate at higher internal temperatures, producing more lumens per watt and brighter light than ordinary incandescent; lamp life is also extended. Halogen lamps include A, MB, T, PAR and MR types.


Heat exchanger

A piece of equipment built for efficient heat transfer from one medium to another and are widely used in space heating, refrigeration, air conditioning. A common example of a heat exchanger is a car radiator where the engine-cooling fluid transfers heat to air flowing through the radiator.  



Hydronics Institute, Division of the Gas Appliance Manufacturers Association

Hydronics Institute Division of GAMA
PO Box 218
Berkeley Heights, NJ 07922

tel: 908-464-8200
fax: 908-464-7818


High-intensity discharge (HID) lamps include the types of electrical lights: mercury vapor, metal halide, high-pressure sodium and other less common types. The light-producing element of these lamp types is a well-stabilized arc discharge contained within a refractory envelope (arc tube).


Compared to fluorescent and incandescent lamps, HID lamps produce a much larger quantity of light in a relatively small package.


High Pressure Sodium

High pressure sodium (HPS) lamps are smaller and contain additional elements such as mercury, and produce a dark pink glow when first struck, and a pinkish orange light when warmed. Some bulbs also briefly produce a pure to bluish white light in between. This is  probably from the mercury glowing before the sodium is completely warmed. The sodium D-line is the main source of light from the HPS lamp, and it is extremely pressure broadened by the  high sodium pressures in the lamp; due to this broadening and the emissions from mercury, colors of objects under these lamps can be distinguished. This leads them to be used in areas where good color rendering is important, or desired. Thus, its new model name SON is the variant for "Sun" (a name used primarily in Europe and the UK). HPS Lamps are favoured by indoor-growers for general growing because of the wide colour-temperature spectrum produced and the relatively efficient cost of running the lights.   High Pressure Sodium


High pressure sodium lamps are quite efficient—about 100 lm/W—when measured for photopic lighting conditions. They have been widely used for outdoor lighting such as streetlights and security lighting.


Acronym:  Heating, Ventalation, Air Conditioning, Refridgeration and Lighting