Chapter hvac engineering Fundamentals: Part 1 Introduction

4.5.1
Changes due to altitude
Atmospheric pressure and related air density decreases as altitude or
elevation above sea level increases. Inversely, atmospheric pressure
increases for those elevations below sea level or some other reference
point. At elevations up to 6000 ft where the altitude / density variation
is nearly linear, the rate of density change is approximately 3 to 4
percent per 1000 ft of elevation change. This corresponds to furnace
manufacturer’s counsel to derate natural draft burner equipment at 4
percent per 1000 ft elevation. Altitude effects are often ignored below
Design Procedures: Part 2
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