Drinking water expansion vessel - what do you need it for?

Where expansion vessels are used, how they are constructed, and their exact purpose is explained in detail here.

Pressure equalization in drinking water pipes

Water is not compressible. This poses a problem in many cases when the line pressure fluctuates within a drinking water installation. Especially in conjunction with pressure boosting systems that have to meet a complicated control task, the use of appropriately sized expansion tanks has been proven for a long time.

A pressure booster system must maintain as constant as possible line pressure despite changing water extraction. The control of the two to six pumps that make up a pressure booster has to fulfill a complex task.

If, on the other hand, a suitably dimensioned expansion tank is available, the pressure fluctuations will no longer be so extreme, and the control of the pressure booster system will have to work much less. This also protects the system and extends its service life significantly.

Another application for expansion tanks is in conjunction with water heaters. Even with boilers occur by the heating of the water pressure fluctuations that can repeatedly respond to the safety valve. With a connected expansion tank, these fluctuations are buffered and the safety valve does not need to respond as frequently.

Construction of modern expansion tanks

Today, modern equalizing tanks are practically only constructed as membrane balancing vessels. They consist of two containers separated by a membrane. In one container is the water, in another a gas. As a rule, nitrogen is used today because nitrogen is not corrosive and does not attack metal in the long run.

If the water pressure in the chamber rises, the pressure on the rubber membrane is transferred to the filling gas, which is compressed. If there is a chance of the water draining into the line, the gas expands again, pushing the water back into the line.

Tips & Tricks

When buying, you should always make sure that the entire device consists only of corrosion-resistant materials (stainless steel, galvanized steel, gunmetal or brass). Then there is no risk of rust in the drinking water that comes from the expansion vessel. In hygienic terms Legionella) but the use must be well planned.

Video Board: WHITE EXPANSION VESSELS - Drinking Water