Space heaters

Whenever unvented combustion occurs iadoors or when venting systems attached to combustion units malfunction, a variety of combustion products win be released to the iadoor environment. Iadoor combustioa units include nonelectric stoves and ovens, furnaces, hot water heaters, space heaters, and wood-burning fireplaces or stoves. Products of combustion include CO, NO, NO2, fine particles, aldehydes, polynuclear aromatics, and other organic compounds. Especially dangerous sources are unvented gas and kerosene [8008-20-6] space heaters which discharge pollutants directly into the living space. The best way to prevent the accumulation of combustion products indoors is to make sure all units are properly vented and properly maintained. 

Occurrence. Carbon monoxide is a product of incomplete combustion and is not likely to result where a flame bums in an abundant air supply, yet may result when a flame touches a cooler surface than the ignition temperature of the gas. Gas or coal heaters in the home and gas space heaters in industry have been frequent sources of carbon monoxide poisoning when not provided with effective vents. Gas heaters, though properly adjusted when installed, may become hazardous sources of carbon monoxide if maintained improperly. Automobile exhaust gas is perhaps the most familiar source of carbon monoxide exposure. The manufacture and use of synthesis gas, calcium carbide manufacture, distillation of coal or wood, combustion operations, heat treatment of metals, fire fighting, mining, and cigarette smoking represent additional sources of carbon monoxide exposure (105—107). 

It is recommended that the motor should have separate terminal boxes for the main supply and for the accessories such as space heaters, embedded teinpertiture detectors, bearing temperature indicators and moisture detector terminals, etc. In LT motors, however, if it is not possible to provide a separate terminal box for these accessories, the main terminal box may be adequately spaced to segregate the.se terminals from the main terminals within the box. 

Space heaters motors above 30 kW must be provided with anti-condensation space heaters suitable for 240 V 50 Hz (or 60 Hz), a.c. supply. The space heaters must switch ON automatically when the motor is out of. service. Motors of 30 kW and below must be suitable for connection to a 240 V. 50 Hz (or 60 Hz) a.c. supply. Here also the windings must be connected automatically to the 240 V supply when the motor is out of service. 

In HT motors the terminal box for space heaters and embedded temperature detectors must be separate from the main terminal box. 

In certain cases, where the motor is too large and it is idle for a long period before it is installed and electrically connected (the space heaters are therefore OFF) even these heaters may not be sufficient to absorb moisture which might have condensed deep in the slots, unless, of course, the heaters are kept ON for a considerably long period. In such cases, it is advisable to heat the motor by methods 1 and 2 in addition to using the built-in heaters, until the insulation level of the windings reaches the required level. Once the motor has been installed, these space heaters, when provided in the windings, are switched ON automatically as soon as the motor is idle, and thus eliminate deep moisture condensation. 

Detection of moisture condensation in the windings (by space heaters) 12/307... 

Motor space heaters above 30 kW control bus voltage generally... 

The interpanel control wiring tor interlocking between feeders, space heaters and panel illumination will also run through this wireway or control bus chamber,... 

Figure 13.34 Rear view of a typical MCC showing space heaters at the bottom of each cable alley and shrouding of the live parts...

Reversitig DOL starter Star-delta starter Auto transformer starter Primary resistance starter Dual-speed starter Three stage stator-rotor starter Schematic for panel space heater and internal illutnination Schematic for instrutnent wiritig... 

Figure 13.61 Schematic for panel space heater and internal illumination...

All ihe circuits may carry current based on the diversity i actor. The loads may be substituted by space heaters. 

Locations having low ambient temperature or high humidity may adversely affect the insulation level of the bus system. In this case an ordinary space heater may not be adequate and a separate anti-condensation arrangement may become imperative to dry the condensate and to maintain a high dielectric strength. This may be achieved by ... 

Inspection of electrical wiring if there is any (such as for space heaters, cold or hot air blowing, enclosure pressurizing or any other protective circuit)... 

Combustion gases—CO, NO Combustion—furnace, cooking stove, space heater, etc. 

Provision is necessary for adequate venting of the steam space. Heaters should have pressure gauges fitted at the steam inlet. In order to achieve effi-... 

Plate-type design (space heaters) Type of heat exchanger characterized by a substantial proportion of its heat output being by way of radiant energy. 

A motor used in standby operation mode should be equipped with a space heater to keep the motor windings dry. In classified areas these space heaters must meet the surface temperature requirement of the specific hazardous area. 

Space heaters, particularly in electrical motors and generators which may be idle for significant periods of time, can also help prevent the accumulation of moisture. Space heaters installed in classified areas must operate at temperatures below high temperature devices. 

Unvented kerosene and gas space heaters leaking chimneys and furnaces back-drafting from furnaces, gas water heaters, woodstoves, and fireplaces automobile exhaust from attached garages environmental tobacco smoke. Humans are normally the main indoor source of carbon dioxide. Unvented or imperfectly vented combustion appliances can also increase indoor COj concentrations. 

Furnaces and boilers sold today must by law have annual fuel utilization efficiency of at least 78 to 80 percent. Gas water heaters operating this way as space heaters are equivalent to the efficiency of pre-1992 furnaces and boilers which had space heating efficiencies typically in the mid-60 percent range. However, the combined efficiency for space and... 

At the end of the nineteenth century, virtually all of the gasoline produced (around 6 million barrels) was used as a solvent by industry, including chemical and metallurgical plants and dry cleaning establishments, and as kerosene for domestic stoves and space heaters. But by 1919, when the United States produced S7.5 million barrels of gasoline, S5 percent was consumed by the internal combustion engine (in automobiles, trucks, tractors, and motorboats). 

I. Space Heaters. A resistive heating device installed in the motor to prevent condensation when the motor is not operating. This requires a special control system. 

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