MODERN HEATING METHODS

Hawera Star, Volume LIII, 26 September 1933, Page 6

MODERN HEATING METHODS

REGULATION OF HUMIDITY.

VALUE TO CHEESE INDUSTRY

HAWERA AUDIENCE ADDRESSED

Claiming that on account of the cheese industry there was no other place in New Zealand deserving of more .study of the .subject than Taranaki, Mr' B. H. Andrew, a heating engineer of Wellington, dealt with several aspects of modern heating, humidity and ventilation in the course of an address at the Carlton Tearooms, Hawera, last night. Although he had not made a study of cheese Mr Andrew ventured that incorrectly regulated humidity was responsible for case hardening with its resultant bad effects, excessive contraction and expansion within the cheese and a bed in the cheese for green fungoid growth. Cheese must be matured at a certain temperature and some cheese rooms he had seen with their badly controlled humidity were a- long way from perfection. The address was delivered under the auspices of the Hawera 'Gas 00., Ltd., and the chairman of directors, Mr B. ! McCarthy, presided. There was a fair attendance of the public. There were certain fundamental factors to be considered in the study of heat, said the speaker, and the first was that heat wa.s always trying to find its own level of temperature. When there were hot and cold objects sale by side, the cold object attracted the heat from that which had the higher temperature. Then the air was continually breathing moisture—taking it in and dropping it when saturation point was reached. It was generally accepted that heat- was an energy and it was measured in English speaking countries by the British thermal unit the amount of heat required to raise 11b. of water through 1 degree Fahr. It was often said, continued Mr Andrew, that heat rises. That was not a matter of fact. What really happened was that cold air pushed the hot air to the higher levels. If that were not the position all the air in the tropics would rise and there would be none on the surface. Everything, with the exception of a vacuum, acted as a medium for heat. In a room the heat travelled through the air and when it reached a wall passed through to the outer atmosphere. That made it difficult to heat a room at a constant temperature. Glass allowed the most rapid flow of heat. SCIENCE OF HEATING “The heating engineer must be guided by the work of the scientist,” said the speaker when referring to the chair of heating which had been established at the Illinois University (U.S.A.) twelve years ago. To the best of his knowledge this was the only university which gave education in heating. One of the most interesting research works at the university took place m an insulated room in which were smaller rooms with walls of variout materials used in the building of houses and other buildings. The temperature of this room could be regulated and from tests it was possible to estimate the amount of heat which flowed through a square foot of a certain material in a given time. When he was estimating the heating of a shop or other building the heating engineer knew from facts what amount of heat would flow through the walls and he based his calculations accordingly. This amount of heat which would flow through the material in a given time was known as the co-effi-cient of heat loss. Having calculated the replacement of heat losses the engineer could ascertain the amount of fuel required. Dealing with heaters of to-day, Mr Andrew said there were two main tvpes—the gravity and the forced air. In the gravity type heat was generated in a sealed furnace with a vent to allow the conveyance of fumes. The furnace was contained in an air chamber which could draw air from the floor only. When the heater was set in action the specific gravity of the air was lightened and the heavier cold air forced this heated air into motion. This cold air in -turn became heated and in its turn was displaced by more cold air. When the heated air became cold again it dropped and was again heated. The process resembled a dog chasing its own tail. In the forced air type the same principle as that in the gravity heater obtained, except that a small fan in the air duct had the effect of forcing the air away and thus stimulating the current. HEAT AND COMFORT

“A temperature of 65 degrees Fahr. is the most suitable for human beings,” said the speaker as lie displayed a graph showing the constant 65 degrees and a wavy line beneath it representing the actual temperatures.on numerous days in Wellington. There could be no comfort without this constant warmth.

It had been proved that a great quantity of heated air was drawn up through the chimney, continued the speaker when referring to the fire-place system of heating. Twenty or 30 years ago this loss was replaced by heated air this loss was replaced by heated air which was drawn from around the oil or kerosene lamp suspended from the ceiling and thus warmed the back of the person who was sitting in front of the fire. With the passing of the lamp and the substitution of other forms of lighting which provided no heat, the suction of heated air up the chimney and the resultant suction of air from the other parts of the room continued, but these currents of air were not laden with heat and the person in front of the fire received a cold current on the back. The alteration of the lighting system altered the heating requirements. Air Andrew displayed a diagram which illustrated the central heating system, the cold air in the basement and the heated air being circulated throughout the rooms. Important factors in the system were that it could be easily controlled and could be stopped almost instantly. There was now a method of washing the air bv means of a spray of fine particles of water which attracted the dust and carried it away. The heaters could be thermostatically controlled and a temperature set for any hour of the day. Humidity was appreciated in U.S.A. and Canada, but not very much in New Zealand, continued the speaker. Humidity meant the vapour content of the air. This vapour content was always changing and it had to lie remembered that the atmosphere held different quantities at different times. The most advantageous degree of humidity for human beings was 50 per cent, of what moisture the atmosphere could retain. A drying room must let the boat out. concluded Mr Andrew. The atmosphere reached saturation point and would not

accept any more moisture. More air must bo let in to draw out more moisture. The speaker answered several questions from members of the audience and on the motion of Mr E. A. Pacey, seconded by Mr L. A. Taylor, was accorded a. vote of thanks for his address.