Reducer or regulator of water pressure in the water supply system for a house and apartment

Recommendation points

• Water supply performance
• Requirements for connecting plumbing and household equipment.
• Gearbox types
• Use in piping of a pumping station
• Local gearbox connection
• Setting the DHW circuit
• Installation requirements

Centralized water supply systems rarely shine with exemplary performance and stability. Water hammer, pressure surges or simply the need to limit it to acceptable values ​​- these are the main indications for installing a pressure reducer or pressure regulator.

Water supply performance

The operation of cold and hot water systems is determined by such key characteristics as pressure and head. Both of these parameters are governed by government regulations. In this case, one should distinguish between the concepts of system characteristics at the supply node to an apartment building, at the entrance to a residential building and at the point of connection of plumbing fixtures.

SNiP 2.04.02–84 defines a general calculation formula for multi-storey residential buildings. If we assume that the pressure on each floor should be at least 10 m. Water. st (1 atm), then on each floor above the first one should add 4 m. water. Art to ensure sufficient pressure at the inlet. It is obvious that the pressure in the apartment on the 1st floor can be significantly higher than on the topmost one, this is due to technological necessity. It is interesting that at the same time SNiP 2.04.01–85 sets the minimum and maximum pressure values ​​at the entrance to the apartment: no more than 4.5 bar for hot water supply and no more than 6 bar for cold water supply.

If you look at it, then without special equipment with a natural pressure drop, cold water can be supplied with up to 12 floors, hot – up to 9. And this is provided that a stable pressure is maintained at the entrance to the house not higher than the established limit. In real conditions, the pressure at the inlet to the house has to be significantly overestimated, otherwise, at peak consumption, the pressure drop will be so large that there will be no water flow at the highest points of draw-off. And if the pressure goes beyond the established norms, the effect of operational switches in the water supply system and the pressure surges caused by them will be even more destructive. In this regard, on the lower floors of buildings, it is necessary to limit and normalize the pressure at the local section of the water supply system, that is, simply install a reducer or regulator.

Requirements for connecting plumbing and household equipment.

Norms are norms, but the requirements for connecting plumbing fixtures also apply. The classic “four” household plumbing – a toilet, a washstand, a bathroom and a shower – require a minimum pressure at the connection point of at least 0.2–0.3 atm, which fully complies with current standards. In this case, the maximum pressure value is determined solely by the characteristics of the equipment and in most examples is at least 6 atm, which is also within the standard parameters.

The situation is more complicated when connecting atypical appliances and household appliances. The range of parameters is greater here: the minimum pressure for connecting a high-quality shower stall can be from 1 to 4 atm, and in the presence of a tropical shower system – from 3 to 5 atm. At the same time, in the case of installing a tropical shower, the maximum pressure is also limited, as a result, the working range turns out to be very small – about 0.6-1 atm. It is quite difficult to ensure the stable operation of devices with different requirements for water supply parameters, especially with a large branching system.

To organize a water supply network for an apartment with a large number of diverse consumers, the installation of several pressure reducers is required. One is installed at the tie-in point into the main riser, the maximum outlet pressure is determined by the permissible values ​​of the equipment that requires the highest performance. So, in the presence of a tropical shower, it will be about 4-5 Atm, in its absence – 6 Atm.

Additional gearboxes can be installed on the collector taps. For example, if the system provides for a separate water supply line to the washing machine, for which the maximum pressure is limited to 2–3 atm. If there are several draw-off points on the collector outgoing line with different pressure requirements, it is most appropriate to locally install the reducer at the equipment connection point. The ideal way of organizing water supply systems is considered to be one in which consumers of the main “four” are connected through a separate collector with a 1-1.5 atm reducer to reduce water consumption.

Gearbox types

Reducers differ in design and principle of operation for diaphragm, valve and labyrinth. Valve devices are most widely used due to their low cost, simplicity of the device and the ability to regulate the outlet pressure over a wide range..

Diaphragm reducers are more expensive, but at the same time they are not so sensitive to the presence of mechanical impurities in water and have the greatest throughput. In this case, the regulation of the pressure at their outlet is performed with a higher accuracy and, as a rule, in a larger range..

1 – valve reducer KFRD2.012-0; 2 – membrane reducer KFRD10-2.0 (SUIE.493611.008)

Labyrinth gearboxes do not have active mechanical components, they simply limit the pressure due to a system of small channels, which is why they are optimal for local installation at equipment connection points.

Reducers of all types have a set of operating parameters that determine the possibility of their use in a particular water supply system. These parameters include maximum inlet pressure, water temperature, diameter and connection type. Additional differences may relate to the control range and limiting flow rate. Also, the manufacturer may indicate some specific requirements, for example, for pre-filtration or installation site. Gearboxes can also be distinguished by their layout.

The device can have a static factory setting, that is, there is no flywheel for adjustment in its design. Also, in addition to the pressure reducing valve itself, one housing may contain:

• mechanical cleaning filter;
• stopcock;
• pressure gauge.

Usually, only a single-case version of the gearbox with a pressure gauge that facilitates the adjustment process is justified. It is advisable to install two such reducers as the main ones at the points of tie-in into the hot water and cold water supply pipes. Additional reducers installed at the manifold feed points may not have pressure gauges. If necessary, it is better to place the measuring device on the designated branch of the distributor.

Use in piping of a pumping station

Usually, when the water supply system is powered by an autonomous pumping station, the installation of a reducer is not required. It is considered that the pressure regulator from the pump automation group maintains the system operation within the set parameters, avoiding critical drops and surges. However, as with any rule, there are exceptions..

Some borehole pumps can cause sudden pressure surges during operation. It happens so that there is a certain time delay between the opening of the water draw-off, the activation of the switch-on relay and the output to full power. In this case, in the final section of the system, the pressure drops sharply, while near the source, on the contrary, its growth is observed. As a result, a front of a kind of shock wave is formed, which follows from the initial to the final point of the system. Given the fact that, in the general case, the water supply system is not designed for a dynamic change in the main parameters, such processes cannot have a beneficial effect on the durability of the equipment..

Another special case is the operation of a pump without a hydraulic accumulator under the control of an electronic pressure regulator. This principle of operation is most typical for systems that include storage heaters. The air pocket in the upper part of the tank acts as a damper, however, the boiler cannot be called a full replacement for the accumulator. It is possible to avoid constant pressure surges when the station is turned on and during operation by installing a pressure reducer immediately after the pump check valve, thereby protecting the rest of the system components from the destructive effect of water hammer.

Finally, a wide range of equipment and technology with different pressure requirements in the water supply system can be connected to the water supply system of a private house, just as in an apartment. Even if the pumping station is configured correctly, equalization of pressure in different branches of the system can only be handled by installing several pressure reducers with an appropriate setting of the outlet pressure.

Local gearbox connection

Washing machines and dishwashers, as well as showers, often cannot be installed on individual construction sites, simply for the reason that the water supply system does not have a sufficiently high pressure. In the utilities sector, the situation is exactly the opposite. This kind of equipment is the most vulnerable part of the water supply system, an excess of pressure even by 10-20% above the limit values ​​set by the manufacturer can lead to breakdown of the inlet valve or the internal piping system.

Labyrinth-type gearboxes reliably protect household appliances from high pressure. And although their cost is in principle comparable to valve and diaphragm devices, there is a big economic difference in the location of the gearbox. Inserting a pressure regulator into the mainline involves removing a part of the pipeline and installing connecting fittings, which often cannot be done without special equipment and appropriate qualifications. The installation of the gearbox directly at the point of draw-off requires only an adjustable wrench and a roll of sealing tape.

The gearbox must be installed immediately after the shut-off valves for replacement and service. Labyrinth reducers are most sensitive to the presence of mechanical impurities in the water, therefore, if the water supply system does not have a filtration unit, a filter must be installed at the gearbox inlet. For this, it is most rational to use compact mechanical cleaning filters. Installation of a filter with a built-in pressure reducer is also justified..

Setting the DHW circuit

If we compare the pressure in the nozzles for connecting the mixer, it will always be lower at the hot water outlet. At the same time, there is no difference in whether the hot water supply is carried out centrally, or the heating device is part of the local water treatment system. In both cases, the hot water supply network has an additional node, due to which its hydrodynamic resistance is higher, and accordingly, the pressure drop is greater. Due to this difference, incorrect operation of the mixers is possible: inability to accurately adjust the temperature, setting failure from time to time, etc..

For correct operation, it is required that the pressure in the hot water and cold water pipelines be the same with an allowable difference of up to 0.1–0.2 atm. Please note that with the main supply of hot water, the pressure regulators are installed at the entrance to the apartment. As already mentioned, the presence of built-in pressure gauges is optimal to increase the convenience of simultaneous adjustment of both devices..

If the water heating unit is part of the apartment water supply system, the reducer for the hot water supply must be installed already at the boiler outlet. If such an arrangement is inconvenient, adjustment can also be made on the power supply branch of the heating device, however, in this case, it is required to install a control pressure gauge on the DHW branch, for example, on the distribution manifold.

Installation requirements

Most reducers for domestic water supply systems are designed for threaded connections with a diameter of up to 50 mm, for larger pipelines, a connection on flanges is used. The installation process itself is extremely simple, here it can be performed as a rigid package using a Teflon sealing tape, or threaded union nuts with O-rings.

The situation is somewhat different with the choice of the installation site. If the reducer is located immediately after the inlet tap, all other elements of the water supply network will operate under stable pressure, which may seem the most optimal option. However, in this case, coordination with the local water utility and sealing of the unit after installation is required. This will complicate subsequent replacement or maintenance of the device..

By the way, a coarse mechanical filter and a water meter normally tolerate pressure surges, so the reducer can be installed immediately after the check valve behind the metering unit. It is desirable that the usual strainer be replaced by a compact flask with a 100 μm cell. It is imperative to follow the correct direction of movement of the liquid, which is indicated by the arrow on the body of the device. If the gearbox has a built-in pressure gauge, the latter must point upwards during installation.

The gearbox is adjusted when there is no flow at all. After the adjustment is made, it is necessary to cut through a few liters and make sure that the pressure is still correct or make a new, more accurate adjustment. Subject to the installation standards, the water pressure regulator does not need maintenance; it may only require periodic flushing of the built-in filter.