Showing posts from July, 2018

Watt the BTU . . . ?

When deciding whether to buy or hire a portable air conditioning unit, you may come across the term ‘BTU’ or alternatively Kilowatts.     BTU stands for British Thermal Unit and in the world of HVAC  is the amount of heat that an air conditioner can remove from a room.  If an air conditioner’s capacity is measure in Kilowatts then one Kilowatt is equivalent to 3,412 BTUs.  For the science-minded among us, One BTU is the amount of energy needed to raise 1 pound of water 1°F at sea level. Why are BTUs or Kilowatts important when choosing an air conditioner?   Having the correct number of BTUs for the space you need to cool means that the room will be cooled efficiently.   It should also be borne in mind that as the BTU rating increases so does the weight, size and cost of the air conditioner. Too high a BTU means that although the room will cool quickly, the unit will cycle   on and off once the temperature is   reached and to keep it   at that temperature, overworking the

Air conditioning – a condensed history

The first air conditioning systems were in use as early as 1902, but they were not for the comfort of people! According to Tim Hartford of the BBC World Service [1] , Sackett & Wilhelms Lithographing and Printing Company in New York found that varying humidity levels affected the quality of their printing.   The paper had to be printed up to four times in four colours and changing humidity made the paper expand or contract slightly, misaligning the print.   The company approached a heating company, Buffalo Forge, to devise a system to control the humidity.   Engineer Wills Carrier invented the first modern type of air conditioning in which air circulated over coils chilled by compressed ammonia which kept the humidity at a constant 55%. Carrier’s invention soon proved popular in industries where excessive humidity was a problem – such as flour mills and the Gillette Corporation, where excessive moisture would cause the razor blades to rust. The benefits for workers