There are three forms of heat transfer. They are conduction, the transfer of heat between materials; convection, the effects of heat on air; and radiation, the heating effect from a single source. The most commonly used form of heat transfer in the home is conduction, although in many occasions, two types of transfer occur simultaneously.
The best example of conduction in the home is the cooking of good on the stove. Food in a pan is heated from the gas or electric supply underneath. The pan is made from steel, copper or iron as these are good conductors of heat--the temperature created by the gas or electricity is easily transferred to the substance in the pan. The main part of the oven also uses conduction in conjunction with convection. A ovenproof dish is a good conductor as it transfers the heat from the oven to the food in the dish, but convection inside the oven means it is hotter at the top due to warmer air rising.
A basic household radiator is another prime example of conduction, but also uses radiation to heat rooms. The heat created when a radiator is conducted into the room through the metal, which is a good conductor, but the room itself is then heated by a central point, which makes it radiation. The basic principle applies to the majority of heating in a home, be it standard metal radiators, under floor heating or any other system.
Conduction is usually referred to as how well a substance transfers heat, but it also covers materials which deliberately do not transfer heat. Fibreglass insulation, for example, is a bad conductor as it transfers heat poorly, acting as an insulator. This is why many roof spaces are lined with fibreglass or another insulating materials to stop heat escaping through the roof, reducing energy costs and carbon emissions. This concept is the same for cavity walls and double-glazed windows as the air trapped in between is also a poor conductor.
Water in homes is heated by a central boiler which uses conduction to warm the liquid. The water from the main supply enters the home through pipes and is drawn through the boiler. The boiler has a number of heating elements powered by electricity. These are normally made from copper or a similar good conductor and transfer the heat to the water which then comes out of faucets and showers.