![]() ![]() It is similar to what happens when you keep bending a paper clip. Embrittlement is the loss of ductility of the metal. This could develop higher than desired levels of carbon monoxide.įlame impingement also could cause embrittlement of the boiler metal, lowering the life of the boiler. ![]() In addition to increased operating costs, the high draft can cause flame impingement on the boiler. Excessive draft inside a boiler can cause other strange behaviors. If the draft inside the chimney is greater than the setpoint, the damper will open and allow air from the boiler room inside the chimney, rather than stealing heat from the boiler.ĭraft controls are typically used when the stack or chimney height is greater than 30 ft. It is set for the desired draft conditions using weights and adjustment screws. The barometric damper is installed in the flue between the boiler and the chimney. High draft will pull the flue gases too quickly through a boiler, not allowing the heat to be transferred into the boiler. How do you provide a buffer to handle these erratic swings?Ī barometric damper is a great solution. The draft conditions inside the chimney could cause swings of 10, 20 or even 100 times that amount. The boiler requires a stable environment and the chimney is like the “wild child.” Most older boilers were designed to have a draft at the outlet of the boiler to be about -0.05 in. When a tall chimney is attached to a boiler, the draft readings will vary greatly. When both sets of doors were opened simultaneously, the wind would whip into the building at high velocities. During the rush hour on a cold morning, the negative conditions inside the building would be very high. The main entrance to the building used to have a set of double doors with a small vestibule, which was directly in front of the main escalators for the building. ![]() Here, in my hometown, a large commercial building once had some real issues from the excessive chimney effect in the building. During cold startups, the cold stack may allow spillage of the flue gases into the boiler room until the stack warms enough to sustain draft.Ĭhimney effect is sometimes experienced in tall buildings. This wastes money as the heat does not have time to transfer to the boiler. In lesser conditions, it could simply pull the heat more quickly than desired through the boiler. In some instances, excessive draft could actually pull the flame off the burner. On cold days, the draft may be very high. ![]()
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