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Chimney Calculator

The Excel™ spreadsheet offers a means of determining the required height of a chimney when provided with the mass flow of flue gas, its temperature, the number of 90° bends, the horizontal length, and the internal diameter of the flue. By adjusting the various parameters the calculations can be quickly made for a number of boilers and flue sizes. This system is specifically designed to suit the KÖB Viessmann ranges of biomass boilers.
The intention is to produce this program as a Java Desk-top application together with the D1 calculation which is often required at the same time. They will be provided as separate programs later in the year.


We have produced a new programme based on the LAQM-TG-09 document which attempts to indicate the effective chimney height for any biomass boiler. The minimum information required is the maximum output (kW), efficiency (%), internal chimney diameter (mm), NOx emission (g/GJ), and PM10 emission (g/GJ).

This is in the development stage so your feedback would be very much appreciated. It is available on the download page.

Thank you for your interest,
George Fletcher

updated 31/07/2012

George Fletcher