Boiler draft hoods are vital for proper boiler furnace function, and are intended to allow draft control around the area of the furnace. These hoods also function to take the fumes from the boiler away from the surrounding area, and draw them into pipes which lead to the outside air. Draft hoods protect the inhabitants of the house from being overcome by toxic fumes, and therefore provide an essential function in keeping you and your family safe while the boiler is running. On the downside, it also draws essential heat from the boiler and the room atmosphere, and so can increase your heating charges.
Different Styles of Boiler Draft Hoods
There are 2 major styles of boiler draft hoods currently in use. The first is probably the most familiar, being an inverted cone shape which lies 1 inch or so above the boiler itself. The hood points down towards the boiler, but draws fumes up and through the pipe. The second style is more like a box shape, with the draft hood gap along the edge which faces into the room. This kind of draft hood is much more common in commercial and business buildings. Some modern boilers have eliminated the need for a boiler completely by installing an exhaust system which includes a draft fan. This does not take in air from the surrounding room, and so helps to cut costs.
Using a Damper
Draft hoods can sometimes be fitted with draft dampers. These are fitted further on from the draft hood, and serve to turn off the drawing of air into the hood during periods when the boiler is not being used. These dampers, also known as vent dampers, close down after a short period when the boiler is turned off, and then re-open before the furnace begins functioning again. This helps to prevent heat loss, while still keeping the air free of toxic gases. Dampers can either be bought with the boiler, or fitted later as part of a fuel efficiency drive.
Performing a Boiler Draft Hood Test
A simple test of the boiler draft hood will tell you whether it is working well or not, although you may wish to perform it several times in order to check the consistency of your results. Performing this test is not difficult or time-consuming. The first thing you need to do is to close all doors and windows, including interior bedroom doors. Other doors, such as those on the lower floors, and the bathroom door, should be opened. Turn on exhaust fans, water heaters, and the clothes dryer. Turn on the boiler furnace, and allow a minute for the draft to become consistent. Hold an object such as an incense stick, or other smoking device, 1 or 2 inches from the draft hood opening. If the smoke is taken into the hood, the boiler furnace is working correctly. If the smoke is not drawn down, or even blown away from the hood, you may have fumes leaking from the hood. Open windows and call your gas company at once.