This caused wet steam and tripping of the low water cutoff. It caused violent surges and waves inside the boiler. We had a vertical fire tube steam boiler that had flame being drawn into the rear tubes of the boiler. In most instances, the flame should stay inside the combustion chamber. Flame impingement means that the burner flame is touching the metal surfaces of the boiler that were not designed to have flame on them. It is like what happens when you keep bending a paper clip. Embrittlement is the loss of ductility of the metal. Flame impingement could also cause embrittlement of the boiler metal, lowering the life of the boiler. This could cause higher than desired levels of carbon monoxide. In addition to increased operating costs, the high draft can cause flame impingement on the boiler. Excessive draft inside a boiler can cause strange behavior. If the draft inside the chimney is excessive, the damper will open and allow air from the boiler room inside the chimney.ĭraft controls are typically used when the stack or chimney height is greater than 30 feet. The barometric damper will be set for the desired draft conditions using weights and adjustment screws. The barometric damper will be installed in the flue between the boiler and the chimney. The boiler manufacturer will inform you of the draft conditions that would like to see on their boilers. High draft will cause excessive velocity of the flue gases and this will not allow the heat to transfer into the boiler. How do you provide a buffer to handle these swings? A barometric damper is a great solution. The draft conditions inside the chimney could cause swings of ten times that amount. On older boilers, they were designed to have a draft at the outlet of the boiler to be about -0.05” w.c. The boiler requires a stable environment and the chimney is like the “wild child”. When a chimney is attached to a boiler, you can imagine the wild effects that occur inside this transition. The building owners replaced the double doors with large revolving doors in an effort to combat the building’s chimney effect. There was no report on the male witness’s emotions but a general sense of feigned outrage was felt. These powerful gusts of wind would blow up the women’s dresses, embarrassing and then angering the wearer.
It would suck air into the building causing great gusts of wind. When both sets of doors were opened simultaneously, the draft was very high. During the rush hour on a cold morning, the draft inside the building would be excessive. Here in my home town, a large building used to have a set of double doors with a vestibule in front of the main escalators to the building. This is called “Chimney Effect”Ĭhimney Effect is sometimes felt in tall buildings. In lesser conditions, it could simply pull the heat more quickly through the boiler, wasting money. In some instances, it could actually pull the flame off the burner. On cold days, the draft can be very high. The speed or velocity of the flue gases up the chimney is affected by many operating conditions such as temperature difference between the outside and the inside of the building, wind fluctuations, chimney height, burner firing rate, and barometric conditions. This flow of air from the boiler up the stack is referred to as draft. The cooler air will push the warm air up the stack. The cooler air is like a bully and will push the warmer, less dense air around. Inside a chimney, the hot air from the boiler is less dense than the cooler air outside the boiler in the boiler room.
This is what allows hot air balloons to rise and float above the earth. Hot air is less desnser than cool air and it weighs less. We all know that when air is heated, it will rise. To understand how the barometric damper operates, we need to understand what draft is. It is installed on boilers that use a Category I vent. The barometric damper is used to control the draft inside a boiler. Categories: Commercial Heating One of the most misunderstood items inside a boiler room is a barometric damper.
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