This draft regulator will alter the draft velocity using weights, for instance, if the draft is excessive it will open and allow air to flow from the boiler to the ventilation. The barometric damper is typically installed in between the furnace flue and the main ventilation (typically the chimney). The real issue with high-velocity drafts is that they can result in flue gases being removed too quickly and also negatively impact heat transfer from the boiler to the environment, which is, of course, the ultimate goal of any heating appliance. In order for this change to be evened out so no dramatic changes result, a draft regulator or barometric damper is the solution to the problem. This is due to a disparity of draft velocity between the heating unit and the ventilation caused by the chimney effect. The furnace requires a constant, stable temperature and environment, while the ventilation’s environment can change dramatically. When ventilation is attached to a furnace there is a significant difference between the two in terms of drafts. On chilly winter days, the draft can be so strong that it is able to remove the flame completely away from the burner, or alternatively, it could result in heat being pulled away, resulting in fuel wastage. These conditions fluctuate and as a result, so does the draft velocity. The speed at which this draft travels is dependent on many variable factors such as temperature, wind, and ventilation height which influence the air buoyancy. This cool air causes the hot air to be forced up the ventilation or chimney.

the furnace is less dense than the air outside in the external environment. Inside ventilation systems, the hot air produced by the heating appliance e.g.

The movement of air through a building, chimney or a flue pipe that is dependent on air buoyancy is what is known as the chimney effect. This results in the movement of air which we know as draft. Now, cool air is a bit of a bully and likes throwing its weight around and it naturally wants to go where the hot air is, pushing the hot air further away. Cool air is a lot denser than hot air, and it’s heavier, meaning that it has the weight to push hot air around. What is Draft?Īs air is heated it rises, this is a common principle in atmospheric pressure that most of us know. In order to explain how they function, it is important to know how draftworks and what the chimney effectis. Barometric dampers are used in a wide range of heating appliances including furnaces, boilers, fireplaces, and stoves.Įven though they are commonly used, they are quite misunderstood and many people don’t realize what they are for, or how they operate. Barometric dampers are a device installed into the flue between the heating appliance and the chimney to control draft.

6 barometric draft control damper