Each owner of a private house always wants his home to be comfortable and cozy. The main amenities are undoubtedly sewage and water supply. The best solution to the issue of water supply of a private house is the installation of a submersible or deep pump or pump station. The installation is called an automatic pump because it supplies water to the house and itself maintains the necessary pressure in the water supply system during its operation.
Such automatic water supply stations are used both in private houses and in summer cottages, as well as in apartments. Their advantage lies in the leveling of water shocks in the water supply system, and in the event of a drop or a power outage, they themselves store the required water supply, that is, a reserve.
Wherever a pump or pump station is used, they always have adjustment sensors. With their help, pumps turn on and off. Therefore, when acquiring such equipment, it is extremely important to choose the right range, when set, the pump will work correctly. If this range is too large, then the pump will react too much to changes, and then the water pressure sensor in the pipeline will respond very often. If the adjustment is too small, then the pump will turn on more often, and this as a result will lead to its failure.
Typically, pressure switch sensors are configured in the store. But if it turned out that such settings were not made, then everyone can do it independently without much effort.
The differential pressure sensor is a critical device. It must be present in every pumping station, and when installing a pump connected to a well or well, it is simply necessary. And the pressure sensor plays an equally important role in such a set of equipment, since it is he who gives the pump the right moment to turn it on or off. Thus, the necessary pressure is maintained in the water supply system.
Only correctly set boundaries of the highest and lowest water pressures will allow the pump not to overheat and work intermittently, which means it will last much longer than if it worked continuously or rarely turned off.
Principle of operation
The water pressure switch sensor is a separate unit, hermetically sealed, in which there are springs that are responsible for the pressure limits. They are adjusted with special nuts using a wrench. The membrane transfers the force of water pressure . They either weaken the spring (at low pressure) or hold its resistance (at high pressure).
Such action of the membrane on the spring leads to the connection and opening of contacts in the pressure switch itself.
When the pressure drops to a minimum, the electric circuit automatically closes, voltage is applied to the pump motor and turns it on. The pump runs until the pressure reaches its maximum value. After that, the relay will open the circuit itself, and the voltage supply to the pump is stopped. As a result, the pump shuts off and waits for a new command. During this period, the heated pump parts cool down and it does not overheat.
As a rule, the water pressure sensor for the pump is installed in the range from 1 to 7-8 bar. The factory setting is automatically activated at 1.5 bar (this is the minimum - the pump turns on) and 2.9 bar (this is the maximum - the pump turns off).
Pressure adjustment
There is a certain direct correlation between the capacity of the accumulator, the pressure of the water supply system and the settings of the pressure sensor. Therefore, before you start setting up the relay, be sure to check the air pressure inside the accumulator.
Important: before setting, be sure to disconnect the relay from electricity.
- drain the accumulator;
- unscrew the side (or bottom) cover on the accumulator;
- using a car tire pump, check the pressure - about 1.4-1.5 atm are considered normal;
- if the obtained value is less, then pump up to the desired level with the pump;
- if the pressure is above normal, then "bleed" the excess by pressing on the tip of the nipple.
Instructions for configuring the relay sensor
It is necessary to engage in the configuration of the pressure switch sensor under pressure in a running water supply system. First, you need to turn on the pump so that the pressure in the system rises until the differential pressure sensor works and the pump turns off.
The adjustment is made by two screws, which are installed under the cover that closes the automation of the relay.
To change the limits of the relay sensor
- Check and fix the existing pressure for switching the relay off and on when the station (or pump) is running. That is, carefully read the pressure gauge.
- After that, disconnect the pump from electricity and, having unscrewed the screws, remove the top cover from the relay and loosen the nut pressing the small spring. Under it are two screws. The largest screw, which is installed at the top of the device, is responsible for the maximum pressure. It is usually denoted by the letter "P". Finding it is not difficult. The second, smaller one, is located below the large screw, and its designation is “ΔP”.
- We proceed to set the minimum pressure. To do this, release or tighten the large spring, which has the designation "P", rotating its screw in the signs "-" - decrease (counterclockwise) and "+" - increase (clockwise).
- By opening the tap, we lower the pressure and wait for the pump to turn on.
- Remembering the readings on the pressure gauge, turn off the power again and continue the adjustment, trying to achieve the optimal rate.
- To adjust the shut-off pressure, release or tighten the small spring marked “Δ” by turning its screw between the “-” and “+” signs, which indicate the difference between the shut-off and switch-on pressures and most often are in the range from 1 to 1.5 bar .
- Turning on the pump, we wait for the water pressure sensor to work. If the result does not suit us, then drain the water again and continue adjusting further.
Features of adjusting the water pressure sensor
When the shutdown pressure increases, then ΔP increases. By default, the factory settings are as follows: P on = 1.6 bar, P off = 2.6 bar with Δ = 1 bar.
You can set the differential to about 1.5 bar by setting P (off) to 4-5 bar, and P (turning on) about 2.5-3.5 bar. In this case, the pump will turn on less frequently, since as the differential increases, the differential pressure of the water in the system will increase. However, taps can react negatively to water hammer.
When adjusting pressure limits, the pump capabilities should also be considered. If the product data sheet indicates a value of 3.5-4.5 bar, then you need to adjust the water pressure sensor to 3-4 bar. If you do not leave a "gap", then overload is inevitable, and the pump motor will work continuously, without shutting down. Thus, the pressure sensor significantly affects the life of the pump and therefore its condition must be constantly monitored.
If you do not change the factory settings of the sensor, then you should monitor it at least once a quarter. This will extend the life of the pump and avoid unnecessary financial costs.
Possible system malfunctions
No pump or pump station can be operated without water. This is the most common cause of their malfunction, of course, if regular power outages do not occur, which negatively affects the work of not only the pump, but also disables the water pressure sensor.
Most often, pumps use thermoplastic - plastic with increased wear resistance. Its price is low, and the benefits are obvious. However, for the system, water acts as both a lubricant and a cooler. When operating equipment without water, the parts quickly heat up and, as a result, become deformed. This leads to jamming of the motor shaft, and it burns out. In the best case, the pump continues to work, but no longer corresponds to the indicated capacity.
Most problematic use cases
- Wells and wells with a small volume of water. In this case, it is extremely important to choose a pump of the appropriate capacity and correctly configure the water pressure sensor. This is also important because in the summer period, especially on hot days, the underground water level drops noticeably in underground sources and the pump performance can be much higher than required.
- When the pump is on, the water tank must be constantly monitored in order to be able to turn it off in time.
- In dry periods, it is extremely important to monitor the pressure in the network water supply system into which the water pressure sensor is embedded in order to track the moment when the pressure completely disappears.
Types of equipment and relay protection
- Pressure sensor with protection against "dry running". In such devices, it is possible to open the contacts when the pressure drops below the set limit. Factory settings are usually in the range of 0.4 to 0.6 bar, there is no way to change them. This level drops only if there is no water in the system. After eliminating the cause, the pump can only be turned on manually. However, water pressure sensors can also be used. This type of water supply system is suitable for this model only if there is a hydraulic accumulator. The use of such a relay makes no sense without automatic pump operation. It can be used both with a borehole submersible pump and with a surface pump.
- The most inexpensive option is a float switch. It is used in systems for raising water from almost any tank. There are those that can only fill up - opening contacts to stop the pump motor prevents overflow, and those that protect against "dry running". The cable from the float is connected to one phase, and when the water level drops below the level set in the settings, the contacts open and the pump turns off. Therefore, the pump float should be fixed so that water always remains in the tank.
- In-line relay with the function of "pressure switch" ("press control"). The compact flow switch can replace the accumulator and the water pressure sensor in the apartment. It gives a signal to the pump when the pressure decreases to a threshold of 1.5-2.5 bar. If water does not flow through the relay, the pump turns off. The effect is achieved using the built-in flow sensor, which records the flow of water through the relay. As soon as the pump detects the presence of a “dry run”, it will immediately shut off. At the same time, a small delay does not affect its performance.
Relay selection
When buying a relay sensor, you need to carefully study what kind of environment it is intended for. Check the range of its settings and all additional functions, if any.
The main characteristics of the pressure switch
The following characteristics can be considered basic:
- waterproofing;
- simple adjustment;
- simple installation;
- durability and reliability;
- the contact group corresponds to the power of the motor.
The permissible pressure range and the manufacturer are also factors affecting the cost at which the water pressure sensor in the pipeline is sold.
You can purchase any brand, however, in order to properly arrange the water supply system in a private house, it is better to entrust it to specialists.