The journey and evolution of chimneys through ages
Chimneys are not common in Indian households yet. However, Christmas tales often describe how Santa Claus brings gifts secretly at night by sneaking into homes through chimneys. They are a common feature in western architecture and Hollywood movies too. Ever wondered when the first chimney was created? Or who made it? Let’s explore the history and evolution of chimneys through time.
Chimneys in the Medieval Europe
The origin of chimneys can be traced back to the Medieval Europe. Before the 12th century, chimneys were rare in the western culture, as people used heating fires in the centre of a room to warm it. But a few of the ancient chimneys that existed were tubular, while others featured conical tops with rain-protecting side vents. Now, fast forward to the 15th and 16th centuries. This is when tall chimneys became common, and these were often decorated with carvings, niches and inlays. During this time, many inventors and scientists were working to improve on the chimney designs and soon, a major breakthrough was achieved.
The Pennsylvanian fireplace by Benjamin Franklin
Benjamin Franklin, an American scholar, created the ‘Pennsylvanian Fireplace’ in 1742 to improve home heating efficiency. His fireplace could burn fuel effectively while emitting less smoke into the surrounding air. Like any traditional fireplace or metal stove, the Pennsylvanian fireplace could transmit heat by radiation and direct conduction. So, what was the essential feature of this chimney? It also used the principle of convection. This involves producing an air current that is heated and circulating it inside the room, creating a cosy, warm environment. However, there was still no efficient technique to direct the smoke outside the room. The resultant smoke would often get accumulated in the rooms making it difficult to breath. This problem required a solution to ensure that the smoke was directed outside the house.
The Rumford fireplace by Benjamin Thompson
Sir Benjamin Thompson, an American-born British physicist, came up with a new design of chimney that addressed the smoke accumulation problem. He was one of the early scientists to challenge the widely held belief that heat is fluid. In 1795, Rumford created a new chimney based on his concept of heat and called it the Rumford fireplace. In this chimney, he replaced the large fire area present in the existing chimneys with a shallow one, which effectively radiated heat into the room. In addition, the Rumford chimney could be incorporated into the wall rather unlike its predecessors which had a vast brick structure protruding beyond the outside wall of a house. Additionally, he repositioned the throat (opening just above the fire) of the chimney which ensured that smoke left through the chimney rather than spreading into the room. The Rumford chimney significantly impacted house designs from the early 19th century to the Victorian era. As time passed, fireplaces started to take on a more shallow structure, with chimneys often running down an interior wall and rising through the roof.
Modern chimneys
The modern chimney comprises three parts: Throat, smoke chamber and flue. The opening just above the fire is known as the throat, and it narrows to a few inches in width just below the damper, a door that may be closed when the furnace or fireplace is not in use. The smoke chamber uniformly narrows towards the top and serves as a reserve for the smoke trapped in the chimney by winds across the chimney top. The flue, which represents the length of the chimney, is typically lined with metal and made of bricks. Can you guess what diverts the air out of the room? The brick at the top of the throat, which is set into the back wall of the flue. It creates a smoke shelf at the bottom of the smoke chamber, which serves as a deflection point for air currents that may otherwise carry smoke into the room. Some industrial chimneys are more than 300 feet tall because a taller chimney produces more excellent airflow!