Heating the house

The boiler or stove turns cold air into hot. Air enters the boiler cold and comes out hot.

What happens inside the boiler? Air is made up of tiny particles called molecules, too small for us to see, but they are continuously jumping, like balls.

When the air is cold, molecules jump slowly. When the air gets hot, molecules jump faster.

The boiler or stove makes the molecules jump faster. Cold air from a room reaches the boiler through a pipe. In the boiler there is fire. Cold air molecules collide with fire and begin to jump faster. Jumping, they walk away from the fire and go back to the room. Then they collide with you and give you a feeling of heat.

From cold to hot, from slow jumps to fast ones, continually, and again, until the air warms the whole room.

There are many types of stoves and boilers. Some burn wood; other, Coal; other, oil or gas.