Why is a water supply system with a frequency controlled pump speed better than a relay?

Everyone who lives in their country house is familiar with the classic water supply scheme. Simplified, it can be depicted as follows: a submersible pump in a well, a hydraulic accumulator with a pressure switch, a filter:

We open the tap with water, the pressure in the system decreases, the pressure switch reacts to this and turns on the pump. To prevent the pump from turning on often, a hydraulic accumulator is used (a container with a rubber bulb inside). The larger the capacity, the less often the pump will turn on.

There are water supply schemes where water from a well is drawn into a cubic capacity, and then it is distributed from it around the house. But the essence is the same.

There are plenty of disadvantages to such a system. After the pressure drops below the set pressure, the pump turns on at full capacity. These are increased starting currents, water hammer in the system when starting the pump. The pump itself wears out faster with frequent start-up. And if the room for the equipment is small, then the accumulator tank occupies a large area:

In the large capacity of the accumulator, water stagnates with rare use and acquires a rubbery smell. And if you install a pear for drinking water, you will have to significantly overpay, since it is more expensive than usual. And how many examples are there when house owners cannot adjust the system and it is impossible to take a shower normally (there is hot or cold water when the pump is turned on and off).

It turns out that these shortcomings can be easily eliminated by using a device for frequency regulation of the pump motor speed (its smooth start and such shutdown). One of the available models is the Russian frequency regulator Ermangizer (Ermanjiser).

It allows at the stage of installation of the water supply system to abandon a huge accumulator for 50 l and replace it with just volume 5-8 liters. What else does the frequency regulator give? By maintaining the speed of the pump motor, it keeps the pressure in the system always constant. For example, they opened one tap - the pump starts smoothly and works at a third of its capacity. We opened three mixers - the frequency converter raises the speed of the pump motor, its pressure increases and no one will feel the sudden drop in pressure. The one who takes a shower will not burn himself or, on the contrary, he will not be doused with cold water.

Variable speed controller prolongs the life of the pump. Saves energy. Some models have a leakage control (indication). Shutdown of the pump if there is no water in the system. The system excludes water hammer and failure of valves and leakage of seals.

A good overview of the private converter Ermangizer with a demonstration of its work made in this video:

The manufacturer has two modifications for borehole pumps: ER-G-220-02 and ER-G-220-03 (up to 1.2 kW and 2.2 kW, respectively). The plant is set to maintain a pressure of 3 atmospheres. The pressure setting can be changed independently in increments of 0.1.

There are frequency converters on the market for pumping equipment and other brands. But they are imported. An analogue from Grundfos with the SQE system (with a special submersible pump) costs several times more.

In general, I saw some advantages in this device, and I seriously thought about purchasing it, when I get my hands on the arrangement of my own water supply system. This is what I decided to share with the readers. Hope for comments with your experience in installing and operating various pump control systems.

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