Water Tank Pump Maintenance: Dry-Run Protection, Pressure Settings and Noises

In most Saudi homes at least one pump works between the ground tank and the rooftop tank, and many villas add a booster pump to raise pressure in the bathrooms and kitchen. In summer that pump starts hundreds of times a day, and any problem in the tank itself, such as low water or too much sand, lands directly on it. Simple regular maintenance is enough to avoid most costly failures.

What types of household tank pump are there?

Which type you own decides where to look first. A surface pump lives or dies by its suction side, a booster by its pressure switch and air charge, and a submersible by how well it is protected from running dry.

Why is dry running the most dangerous pump fault?

Grundfos, in its explanation of dry-running protection, says the mechanical seal and bearings can be damaged if booster pumps run without water, and it recommends fitting dry-run protection on all booster sets. The water inside a pump does not only get pushed along: it cools and lubricates the seal, so when it is missing the temperature rises within a short time.

The company lists three ways to protect a pump: a pressure switch on the suction line, an electric float or electrode probe in the supply tank; measuring inlet pressure with an analogue transmitter; or measuring the tank level with a level transmitter. In some submersible pumps the protection is built in. Grundfos explains that the control unit in its SQ models detects the drop in power consumption when water runs short, stops the pump, then tries again later.

At home, the electric float in the ground tank is the simplest protection: it cuts the pump when the water falls to a set level. Make sure one is fitted, that its cable is sound, and that the cut-off level is above the suction opening by a good margin. A continuous level sensor with alerts adds an earlier warning, and float settings are covered in our guide to float valve maintenance.

How do you set the pressure switch and pressure tank?

In booster pumps the pressure switch works with a small pressure tank containing a diaphragm and compressed air. The tank holds a small amount of pressurised water so the pump does not start every time a tap is opened slightly. If the tank loses its air, the pump starts and stops rapidly and repeatedly, which technicians call short cycling, and it strains the motor and the switch.

Grundfos, in the manual of one of its household pumps, recommends setting the pressure tank pre-charge at 70% of the required operating pressure and not exceeding it. With a 3 bar operating pressure, the pre-charge would be about 2.1 bar, checked at installation and then yearly. It adds that incorrect setting causes noisy operation, pressure fluctuation, and greater risk of damage and energy use. Always refer to your own pump's manual, because values differ between models.

1. 1

   Disconnect the power

   Switch the pump off at the breaker, not only at its own switch, and make sure it cannot start during the check.

2. 2

   Release the pressure

   Close the supply valve and open a nearby tap until the water stops and the pressure reads zero.

3. 3

   Measure the air pressure

   Use a tyre gauge on the air valve at the top of the pressure tank and compare the reading with the pump manual's recommendation.

4. 4

   Add or release air

   Use a pump to reach the required value. If water comes out of the air valve, the diaphragm is probably punctured and needs replacing.

5. 5

   Restart and observe

   Open the valve, start the pump, and check that the gap between starting and stopping is now longer and the pressure is steady.

What do pump noises and vibration mean?

Noise alone is not enough for an exact diagnosis, but it points you in the right direction. Any work on electrical panels or dismantling the motor must be done by a qualified technician, and a check of the pipework and pump can be requested as part of plumbing services.

Pump maintenance and tank cleanliness are two sides of one job

Sediment and sand on the ground tank floor are drawn into the pump, where they block the strainer, scratch the impeller and speed up wear on the seal. Grains of sand can also lodge in the non-return valve, so the line loses its prime and the pump starts drawing air. That is why tank pump maintenance is never complete without a clean tank. During tank cleaning and disinfection, it is worth checking the height of the suction opening above the floor, because a suction point right on the floor draws sediment directly.

In summer in particular, when demand rises in hot cities such as Riyadh and Al-Ahsa, the pump runs longer hours and its enclosure gets hotter. Make sure the pump room is ventilated and shaded from direct sun, and do not cover it with a closed box that has no openings. A pump installed on a roof needs a shelter that protects it from sun and rain while leaving space for air to circulate around the motor.