Adjusting the pressure switch on the Metabo pump station

How to set up a pumping station for the house

Before setting up, make sure that this is really necessary. The equipment, which is supplied as a complete set, is already set to standard operating parameters. The pressure in the tank is usually 1.5 to 1.8 bar. However, in some cases additional adjustments are required.

Important! It is not recommended to change the factory settings unless absolutely necessary. If you do not know how to adjust the pumping station for the house, and are not sure you can do it right, it is better to trust the professionals. Otherwise it is possible to set the pressure incorrectly, and the station will not start or, on the contrary, will function without interruption.

The adjustment concerns the tank pressure and the relay. Let’s start with the first one. To adjust the air pressure inside the tank, make sure there is no water in it. Then through the nipple in the body with a pump with a manometer pump air, controlling the indicators on the manometer. It is important that the pressure is 90 100% of the required pressure to start up the station.

Now let’s move on to the pressure switch. Each unit has a value for turning the motor on and off. Before starting the adjustment, disconnect the station from the mains and remove the cover from the relay. Inside you will see two springs: the large spring is responsible for the upper pressure level at which the pump turns off, the small spring is responsible for the range between on and off. At the end of the large spring there is a metal bar with a screw. By turning the screw clockwise with a screwdriver you can increase the cut off pressure. For example to increase from 3 bar to 3,5 bar. In this case the range between turning on and off will remain the same. If this also needs to be changed, use a ring spanner to turn the screw on the small spring. To increase the setting range turn clockwise, to decrease the range in the opposite direction.

Remember: the upper indicator of the working pressure of the system should not exceed 95% of the maximum allowable output value, which is specified in the passport of the equipment. Otherwise, the station will work without shutdowns and will soon fail.

If there is not enough water, the pressure is increased. As for the range, increasing it, we risk getting uneven pressure on and off. It is more comfortable for the user when the range is smaller. But too small a range leads to frequent switching on and off the station, which is not very good for the operation of the pump. Therefore, if you change the factory settings pumping station, do not overdo it on the basis of what mode it is comfortable to get water, but avoid too frequent switching on the motor.

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Again, the control of the set parameters is carried out on the manometer. Turn the station on and check if you are satisfied with its operation. If not, unplug it and adjust the pressure values.

It is important to remember! Before beginning the adjustment procedure, the water must be drained from the pump unit and the accumulator. When testing, fill the pump with water to avoid dry running.

How to adjust the water pressure switch with a hydroaccumulator: setting and installation

In systems that are supplied with water from an autonomous source, there must be an accumulating tank, whose function is to ensure the stable operation of the pump and reduce the number of turns on. This would be impossible without a small, but so necessary element, such as a relay, whose duty is to control the head of the water flow. In this publication, we will look at what this device is, and how to adjust the water pressure switch with a hydroaccumulator.


So, let’s understand how to adjust the water pressure in the pumping station. After getting acquainted with the design of the relay and the circuit of its operation, the way of its adjustment becomes quite obvious:

  • By increasing or decreasing the compression of the large spring by turning the nut holding it in place, the user respectively increases or decreases by the same amount both P1 and P2 pressure.
  • When adjusting the small spring compression pressure P1 will remain unchanged and P2 will vary. In other words, the operating pressure range depends on the tension of the small spring and its lower limit is fixed.

Features of operation and maintenance

Like most Metabo power units, the German brand is delivered ready for installation. Even inexperienced craftsmen do not have any difficulty with its installation and connection. For more reliable operation of the equipment, it is recommended to immediately install a coarse strainer on the inlet hose.

Reliable automation ensures reliable operation of the system so that you don’t have to dismantle it every year. The system regulates on/off cycles by itself. The manufacturer recommends avoiding the freezing of the unit. Therefore, it is better to build a special caisson under it, if it is supposed to operate the station in winter.

If you use the equipment only in summer, in the off-season it needs to be disassembled, drained, lubricated and stored in a dry room.

Peculiarities of adjustment “from scratch” and mistakes at adjustment

To tune the pressure switch of a pump station with your own hands from scratch is much more difficult. This procedure is required if the equipment is assembled by parts and not purchased in a store. There are several parameters to consider in such a situation:

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The lack of air in the tank will cause the membrane to fill immediately with water and gradually stretch until it bursts. The maximum pressure at shutdown should be the sum of water pressure and air pressure in the tank. For example, the relay is set to 3 bar. Of these, 2 bars are for water, 1 for air.

Need to adjust the water pressure switch for the pump

Adjustment of the relay, by yourself or with the help of qualified specialists, is required in any case when assembling the pumping station from separate parts. It is possible that the setting of the water pressure switch is required even if the ready-made pumping station is purchased in a specialized store.

This is explained by the fact that each plumbing system is characterized by individual features and the needs of the occupants are also different. The level of water pressure in a house with a shower, sink and bathtub is significantly different from a spacious country house with a Jacuzzi and whirlpool bath. In this case, you need to adjust the water pressure in the water supply system and adjust the equipment individually for each case.

When deciding how to connect the water pressure switch, you should remember that in addition to the initial setting, which is performed during installation of the pumping equipment, in the process of operation it is necessary to monitor and make adjustments to the equipment.

In addition, in the event of replacement or repair of a single element of the pumping station also requires additional adjustment of the water pressure regulator relay. It is worth saying that the process of adjusting the equipment is similar to the procedure of its adjustment.

Design and principle of operation of the relay

Pump station prices

The pumping station is quite compact and has a simple design. The relay itself consists of several elements.

Table. Components of pressure switches.

Factory installations do not always meet the wishes of consumers, which is why very often it is necessary to do self-installation of parameters.

How to configure the recommended parameters

Before setting up the water supply station it is necessary to measure and record the actual values, for which you need to use a manometer. Turn on the pump and record the pressure readings when it is turned on and off. According to the results determine whether to increase or decrease values in deciding how to adjust the deep well pump.

The pump station pressure is adjusted as follows:

  • Disconnect the pump from the power supply, drain it and use a wrench to remove the relay cover.
  • To adjust the trigger pressure, you have to turn the nut that holds the large spring. By turning it clockwise the spring is compressed and the correct cut-in pressure is obtained. Different models can have a pumping station operating pressure in the range of 1.1-2.2 bar.
  • Turning the small spring nut clockwise increases the difference between the on- and off-pressure value. In most cases this difference is equal to the value of 1 bar. This is important to know before you raise the pressure in the pumping station. As a result, the cut-off pressure is fixed to a value located in the range of 2.2-3.3 bar.
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It is very important to understand that by adjusting the small spring it is not possible to set the cut-off threshold. Although many DIY enthusiasts insist on this version. With the help of a small spring, the difference between the switch-on pressure value and the switch-off pressure value of the station is set. When the spring is fully relieved, the difference will be zero and the on and off values will be the same. When the spring is tightened, the delta between the values gradually increases.

To check if the water pressure switch is properly adjusted with your own hands, you need to make a pressure measurement with a manometer. If the recommended values are not obtained after checking, continue the adjustment.

Common mistakes

Relay adjustment does not always go smoothly. These are the situations that happen most often:

The small spring is overtightened

The result is that the cut-off pressure has exceeded the maximum pump head.

In this case, the pump simply will not shut off.

  • energize the pump and start it up;
  • As soon as the pressure on the pressure gauge stops rising, the station must be turned off;
  • by opening any of the taps, drain a small amount of water;
  • Having made sure that the equipment is completely disconnected from the mains, remove the cover from the relay and loosen the small spring until the contacts open with a characteristic click;

You can now put the lid back on and switch on the pump.

Pressure Poff is more than 80% of the maximum allowable pressure for this relay model

Relays in most pumping stations are designed for a pressure of 5. 5.5 atm. This parameter is given in the passport of the product or on the packaging.


Consequently, the pressure Poff for such a device must not exceed 4 4,4 atm.

If this is not enough for a comfortable water supply, you have to install a relay with a higher limiting pressure.

The Pon pressure is set so high (large spring is overtightened) that the pump cannot overcome it and “get” to the operating range

Once again the pump will not switch off.

What to do: Before starting the adjustment procedure, check the data sheet of the pump and find the maximum value of the flow rate. This is normally given in metres of water column (m.в.st.). To convert it into atmospheres, the value given must be divided by 10.34. In all conditions the Pon and Poff values must be less than the highest head that the pump can produce.