The heating value of gas in winter will not be any lower than in summer, because the heating value is increased 1 per cent for each 5º of decrease in temperature of the gas, and will actually be higher during the low temperature of the gas, and will actually be higher during the low temperature period in winter than it is in summer. However, the starting temperature of the food and water that must be heated in cooking will be much lower in winter than in summer; therefore, a larger quantity of heat will be needed to bring the food or water to the boiling point. The radiating loss from the cooking vessel and burner, because of the low temperature of the surrounding air, will also be much higher in winter than in summer, and thus will increase the gas consumption.



Rusting of ovens can almost be eliminated by opening the oven door slightly for a few minutes after the burners are lighted. This permits escape of the greater part of the moisture, which is produced by combustion, and prevents too rapid condensation.

Oven linings and burners are best protected from rust by the application of oil or grease, free from salt. This should be done while the oven or burner is warm, as often as may be necessary.



a. The gas must be burned with perfect combustion. However, this is merely the first step.

b. The combustion products must be made to deliver the most of their heat into the air or water that is to be heated, and before leaving the heating device and going into the flue should be cooled to within 100º of the air or water that is heated. This requires adequate heat-radiating surface, a feature lacking in many appliances. Failure to appreciate the importance of this second step, rather than merely obtaining perfect combustion, is responsible for the gross waste of gas in so many heating devices.

c. The radiant-fire heater works on the same principle as the incandescent mantle lamp; the coarse or heavy radiant element replaces the fragile mantle. However, the radiant-fire heater should never be operated so the radiants glow more than three-quarters of the distance from the bottom to the top. When this rate is exceeded, carbon monoxide is liberated in more or less dangerous quantities.

d. With hot-air furnaces or steam or hot-water boilers, the use of a thermostat for controlling the gas will give more uniform and better temperature conditions in the living rooms and also save gas.

 



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