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Thermal expansion in hot water systems: This article defines thermal expansion in water equipment in response to temperature, and explains the concomitant increase in system pressure. We show how to calculate hot water pressure increase in water heaters and boilers as a function of the increase in water temperature.
Required hot water expansion volume in open, closed and diaphragm tanks. Expansion tanks are required in heating, cooling or air condition system to avoid unacceptable increases of system pressures when water expands during heat-up.
Online Thermal Cubic Expansion Calculator - Expansion coefficient and Temperatures. Be aware that the expansion coefficient for some liquids - like water - may vary with temperature. The calculator below is generic and can be used for metric and imperial units as long as the use of units is consistent.
An expansion tank is used in a hydronic hot water system to accomplish three main tasks, (1) accommodate thermal expansion of the hot water, (2) maintain positive pressure at all points in the system at all times and (3) maintain net positive suction head at the hydronic hot water pump(s).
Definitions, online calculator and figures and tables with water properties like density, specific weight and thermal expansion coefficient of liquid water at temperatures ranging 0 to 360°C (32 to 680°F).
In general, liquids expand on heating, except cold water; below 4 °C it contracts, leading to a negative thermal expansion coefficient. At higher temperatures it shows more typical behavior, with a positive thermal expansion coefficient.
An expansion vessel, or expansion tank, is a device in a heating or cooling system that accommodates the extra volume of water produced when the system water is heated or cooled. As the water heats up, it expands, and without a place to go, this increase in volume can cause a dramatic rise in pressure.
