A chimney cowl is a hood-shaped covering to prevent backflow in a chimney. Most of the time, this part of the chimney is made out of galvanized iron fitted to kitchen areas or fireplaces to prevent wind from pushing back the smoke into the house. According to history, chimney cowls were named from the cowls worn by monks because of the shape and design of the garment. Cowls for chimneys have been in use for hundreds of years now and even today, there are still many homes that use it. Many however are baffled on how the whole thing works.
The main idea for a chimney cowl comes with a scientific explanation –warm air rises. When using open fire to generate heat inside a room, warm air rises up to the house’s chimney and out to the chimney pot located on the roof. This is true under normal conditions; however, in times when there are very strong winds, the smoke might be pushed in reverse making it come back into the house. If this happens, smoke will fill the room and can even cause fire. Apart from the risk of your house catching fire, this can also pose as a health risk and may cause discomfort to the whole family. It would even entail cleaning up the whole house if the air is pushed back in. This is where the cowl serves its purpose, it prevents air from reverting back to your home.
Another function of this overdraft is to prevent birds and other small animals from getting through the chimney or nesting right on the hole. The cowl is also used to protect your chimney pot from rain. Sometimes, metal wire is added to the cowl to function as a spark arrestor to keep the home safe when there is a storm.
