This is not a minor annoyance: every start wears the motor and the pressure switch, and the pump fails much sooner. The most common cause is a pressure tank without air, but it can also be a leak, a faulty non-return valve or a wrongly set pressure switch. Below is what you can safely check yourself and what we do in Riga and the Riga region.
Why the pump starts switching on too often
- There is no air in the pressure tank. Air slowly escapes through the membrane and the valve, and over time the pre-charge drops. Then the pressure tank no longer stores water, and the pump switches on after every glass of water.
- A burst membrane. Water gets into the air side, and topping up the pre-charge helps for only a few days.
- A leak. A leaking toilet cistern valve, a tap, an irrigation system or a crack in a buried pipe: the pump tops up the pressure even at night.
- A faulty non-return valve. Water from the system flows back into the spike well or the borehole, the pressure drops with no water use, and the pump switches on by itself.
- The pressure switch or the pressure tank does not suit the pump. The gap between the cut-in and cut-out pressure is too narrow, or the pressure tank is too small for a powerful pump.
What you can safely check yourself
- Pressure gauge Write down the pressure at which the pump switches on and the pressure at which it switches off. The difference is usually about 1.5 bar. If it is much smaller or the pump runs for only a few seconds, the fault is most likely in the pressure tank or the pressure switch.
- Pressure drop test Once the pump has switched off, disconnect it from the power, close all taps and look at the pressure gauge an hour later. If the pressure has dropped, water is escaping somewhere. If there is a shut-off valve after the pressure tank, close it: if the pressure still drops, the fault is in the non-return valve or the joints before the valve.
- Air in the pressure tank Disconnect the pump from the power and open a tap until water stops running and the gauge shows zero. Measure the pressure at the pressure tank's air valve with a tyre gauge. It should be about 0.2–0.3 bar below the pump's cut-in pressure.
- Membrane Press the valve core for a moment. If air comes out, the membrane is most likely intact. If water comes out, it has burst and must be replaced.
- Topping up the air If there is too little air, you can top it up in the emptied pressure tank with a car or bicycle pump with a gauge. If the air is gone again after a few days, the membrane or the valve is leaking.
Do not open the pressure switch cover while the pump is connected to the power: there is 230 V inside. Leave adjusting the switch to us or an electrician if you do not know which screw changes what.
How we fix it
On site we measure the pre-charge, check the membrane, the pressure switch and the non-return valve, and repeat the pressure drop test. Depending on the cause, we:
- set the correct pressure tank pre-charge and pressure switch limits;
- replace the membrane if the pressure tank has a flange, or the whole pressure tank if the vessel has rusted;
- replace the non-return valve: for a spike well at the pump or in the suction pipe, for a borehole above the pump in the borehole;
- if the pump is too powerful for the pressure tank, fit a larger pressure tank or recommend a variable frequency drive;
- look for a leak in the pipe to the house if the pressure drops even when the taps in the house are closed.
If frequent starts have already damaged the pump, we compare repair with replacement: water pump repair. How to choose the pressure tank size: water pump installation.
Why you should not put it off
Pump manufacturers state how many times an hour a pump may start, and every start heats the motor and burns the pressure switch contacts. Frequent starts also cause pressure surges in pipes and joints. If the pump is in a borehole, replacing it costs much more than servicing the pressure tank, so this sign is worth fixing in good time: borehole pump replacement.
How much does fixing frequent starts cost
The price depends on the cause. Setting the pre-charge and adjusting the pressure switch is a short job. Replacing a membrane or a pressure tank adds the cost of the part. Replacing the non-return valve in a borehole means lifting the pump, which is a bigger job. We name the price once we know the cause from your request or our check. If the borehole pump has to be replaced, installation costs from €200 (pump extra): prices.