The principle behind heating and cooling systems is that heat always moves from a warm object to a cooler object. Modern heating and cooling systems use a thermostat to control the air temperature. It does this by sensing the system’s temperature and maintaining it near the desired set point. A thermostat regulates both the heating and cooling system by promptly switching the device ON or OFF to maintain the system’s desired temperature.
The chemical that helps in the process of heating and cooling, by undergoing phase transitions from liquid to gas and vice versa is called refrigerant. These refrigerants are present within the coils without which the climate control systems would not work. They absorb heat in their liquid state, transforming into a gas. They are then forced to return to liquid form, expelling the heat they absorbed and thus made ready to absorb heat once again. The two commonly used refrigerants are R-22 and the newer R-410A, both of which are chemically known as hydro chlorofluorocarbons, or HCFCs.
The heating/cooling systems also need an air distribution system (a means of distributing the air to the rooms that has to be heated /cooled). Air is distributed either by forced air, gravity or radiant system. A forced air system uses a blower to force the heated/cooled air through the system to the living spaces. Gravity system do not use blowers but uses the concept of convection currents (hot air rising and cold air sinking). The radiant heat distribution system circulates hot air through pipes embedded in the wall, floor or ceiling. Both gravity and radiant systems cannot be used to distribute cool air.
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