Page 18 Advertisements Column 2

Press, Volume CVIII, Issue 31657, 18 April 1968, Page 18

COST PER UNIT OF ENERGY x ONE THERM (100,000 B.T.U.'S) x 100 B.T.U.’s contained in the unit 1 Efficiency of the Appliance An example of this would be:— Oil (Main Centres) —21 c gallon x 100,000 B.T.U.’s (Therm) x 100 161,000 B.T.U.’s 1 75 per cent Efficiency ■= 483 )15400 - 17.3 cents per USEFUL THERM. To carry this exercise to its logical conclusion the seasonal requirements for heating (expressed in “Therms”) should then be multiplied by the cost per therm to establish the total year's running costs. EXPLANATION OF A THERM: A therm is 100,000 British Thermal Units—A measurement of Heat to which all forms of energy can be related. e.g. OIL : 1 gallon - 161,000 B.T.U.’s or 1.61 Therms. ELECTRICITY : 1 Kwt - 3,412 B.T.U.'s or .034 Therms. GAS : 1000 cubic feet = 450,000 B.T U.’s or 4.5 Therms. The term USEFUL THERM means that the efficiency of the appliance has been taken into account in the calculations.