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The draft (draught in British English) flow rate induced by the stack effect can be calculated with the equation presented below. [12] [13] The equation applies only to buildings where air is both inside and outside the buildings. For buildings with one or two floors, h is the height of the building and A is the flow area of the openings.
Normally it is done with the help of a forced draft fan. [2] Induced draft: When air or flue gases flow under the effect of a gradually decreasing pressure below atmospheric pressure. In this case, the system is said to operate under induced draft. The stacks (or chimneys) provide sufficient natural draft to meet the low draft loss needs.
Modern industrial boilers use fans to provide forced or induced draughting of the boiler. Another major advance in the Rocket was large numbers of small-diameter firetubes (a multi-tubular boiler) instead of a single large flue. This greatly increased the surface area for heat transfer, allowing steam to be produced at a much higher rate.
As a result it can be more easily routed through walls or floors. However, the condensing furnace is more expensive initially because of the extra induced-draft fan and condensate pump required, and the extra heat exchanger in the firebox. The heat exchangers may be damaged by corrosion or metal fatigue from many heating and cooling cycles.
The third method is by simply using an induced draught fan (ID fan) which sucks flue gases out of the furnace and up the stack. Almost all induced draught furnaces have a negative pressure. Forced draught: draught is obtained by forcing air into the furnace by means of a fan (FD fan) and duct-work.
Induced draft – A mechanical draft tower with a fan at the discharge (at the top) which pulls air up through the tower. The fan induces hot moist air out the discharge. This produces low entering and high exiting air velocities, reducing the possibility of recirculation in which discharged air flows back into the air intake.
A Virginia family had an unexpected holiday visitor come down their chimney a week before Christmas. A wild barred owl flew into a home through the house's chimney, the Animal Welfare League of ...
The chimney is used for a more important duty. The mantle/wick holder has holes around the outer edges. When the lantern is lit and a chimney is attached, the thermally induced draft draws air through these holes and passes over the top of the mantle, just as a chimney in a house. This has a cooling effect and keeps the mantle from overheating.