Connection diagram of the expansion vessel

The connection scheme of an expansion vessel depends on the function assigned to it. Below are the most common installation schemes for expansion vessels in water supply systems.

In the booster pump station connection scheme

Booster pump stations are installed in facilities with significant water consumption, and usually one of the pumps operates continuously. An expansion vessel for a booster pump station is used to smooth out pressure surges when additional pumps are turned on and to compensate for minor water withdrawals.

In addition, a similar expansion vessel connection scheme is used in water supply systems with frequent power outages, where the absence of water during power outages is not allowed. In this case, the stored water volume in the expansion vessel serves as a reserve that is used during power outages. If the expansion vessel is installed as a buffer tank, its volume will be greater, the greater the necessary water reserve and the smaller the difference between the pump's turn-on and turn-off pressure.

Expansion vessel for a submersible pump

The optimal switching frequency for a submersible pump capable of guaranteeing its long and uninterrupted operation usually ranges from 5 to 20 switchings per hour and is indicated in the technical characteristics of this pump. The pressure switch turns on the pump when the water pressure in the water supply system drops to a minimum value and turns it off when it reaches a maximum value. Water is an incompressible fluid, so even minor water consumption or leakage, especially in small water supply systems, will lower the water pressure to a minimum level and cause the pump to turn on, and within a few seconds, a signal will be received to turn it off again, as there is no water consumption and the pump's leakage compensates for it instantly.

Such an operating mode is not favorable for a submersible pump and can lead to its rapid failure. The water volume stored in the expansion vessel compensates for minor leaks and small water consumption, thereby reducing the frequency of the pump turning on. In addition, an expansion vessel in a scheme with a pump allows smoothing out the instantaneous increase in water pressure at the moment of its turn-on.

The volume of the expansion vessel depends on the optimal switching frequency of the pump, its power, hourly water consumption, and the height of the tank installation.

In a scheme with an accumulator water heater

The expansion vessel in the scheme of connecting a storage water heater performs the function of an expansion tank. When heated, water expands, and the larger the volume of water in the hot water supply system, the greater the volume increase will be. As is known, water is a nearly incompressible fluid, and even a slight increase in volume in a closed circuit will lead to an increase in pressure and the destruction of system components.

The volume of the expansion vessel tank will be greater, the larger the volume of water in the water supply system and storage water heater, the higher the temperature to which the water is heated, and the lower the maximum allowable pressure in the water supply system.

Installing an expansion vessel on the suction side of the booster pump

The scheme of connecting the expansion vessel in front of the booster pumps in the direction of water flow is used to smooth out a sharp drop in pressure in the external water supply network during the switching on of the pumps.

The volume of the vessel will be larger, the greater the water flow and the smaller the difference between the minimum and maximum pressure in the water supply system before the booster pump.

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