How to deal with unstable water pressure in the pipeline with a WILLO station

In MKD the station of increase of pressure of cold water WILLO is installed. The pumps are assembled in cascade system. However, the water pressure in the pipeline is not stable. Fluctuations are up to two bars, and during hours of maximum analysis and more. Is it possible to solve this problem by installing an expansion tank, if so, how to calculate it correctly.

Sergey Viktorovich

Expert Answer

Hello, Sergey Viktorovich.

In order to avoid problems with cold water productivity, pumping stations (systems that consist of several pumps, and a unit with a hydraulic accumulator not familiar to owners of country houses) designed to equip apartment buildings should be equipped with several types of automatic control and protection devices. As a rule, they solve problems:

• maintaining the set pressure when the flow rate changes;

• monitoring the voltage in the network and restarting the system after a power outage;

• switching between individual units in the event of failure of one of them, and also in order to ensure equal wear of all equipment in the system;

• automatic load redistribution when the flow rate changes;

• automatic diagnosis of equipment malfunctions (with sound and visual alerts).

In systems with cascade control, the flow rate is controlled by the inclusion of one or another number of pumps connected in parallel. As a rule, the more units are included in the pump station, the softer, more efficient and more economical it works.

Another way to control performance is frequency regulation, which consists in changing the speed of rotation of the impellers of the pumps by means of an electronic frequency converter. Due to this, it becomes possible to smoothly adjust the performance, it is possible to eliminate water hammer and increase the reliability and durability of the equipment.

And finally, the most “advanced” method combines the combination of cascade and frequency regulation. Such automated pumping stations have all the advantages of the first two and can reduce electricity consumption by half.

Unfortunately, you did not provide accurate information about your engineering system, so we will try to give some recommendations. Perhaps one of them will be useful for your case.

1. When using a modern frequency cascade system, it is necessary to check the correct operation of the PLC (programmable logic controller) and the health of the sensors of the state of the units and pressure. After identifying the "weak link" the problem will be solved by the repair or replacement of the faulty unit.

2. If the pumping station operates according to a simplified scheme, then it is possible to increase productivity and achieve pressure stability by connecting one or two additional units.

3. Perhaps the problems arose due to the long-term operation of the equipment without maintenance or repair? You should not lose sight of the fact of wear of parts and the associated reduction in performance.

As for the installation of a hydraulic accumulator, in apartment buildings this method is not practiced. Judge for yourself: when calculating the expansion tank for one apartment, there must be at least 50 liters of water tank volume. The cost of the accumulator, designed for 1000 or more liters, is prohibitive, so it will be much easier to repair or upgrade the available pump system.