Expansion vessel sizing for POTABLE WATER

The sizing has the following assumptions: Domestic Hot Water tank is connected to expansion vessel near cold water input. Water supply has pressure regulator (operating pressure). Air precharge pressure in expansion vessel at pumping should be 0.2 bar lower than operating pressure to assure the proper expansion function. If this pressure is equal to operation pressure than pressure fluctuation and water hammer effect can occur.

Assumption 1.0 bar ambient air pressure.

Thic calculation can also be used for heating installations T < 90 °C if tank volume is replaced with system volume. For regulated heating systems this method does not work since the expansion of the water is separated into two or more loops with different temperature variations.

Program selects vessel from the following commercial sizes: liters

Operating parameters

Vessel operating pressure: bar
Vessel precharge pressure: bar
Max pressure in vessel (security valve pressure): bar

DHW tank properties

Hot water tank volume: liters
Max temperature in DHW (hot water): ° C
Water supply temperature (cold water): ° C


Select size: or input the size: liters


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Copyright © 2003; Leon Kos
Last modified: Fri May 14 09:35:37 CEST 2004