Water pump not starting or running non-stop: pressure switch, foot valve and leaks

• Switch off the MCB and unplug the appliance before checking anything.
• Make sure your hands and the floor are dry.
• Close the main water valve before opening any water connection.
• Keep water away from sockets and plugs.
• Capacitors keep an electric charge after the plug is pulled; this part is not opened at home.

Pumps are often installed next to a well or tank, where the floor is wet. The motor housing can also be hot after a long run; let it cool before you touch it.

An automatic household water pump has a pressure switch (the Sanei manual calls it the automatic switch or pressure switch) and an air or water tank. When a faucet opens, the pressure in the pipe drops, the switch turns the power on and the motor runs. When every faucet is closed and the pressure builds again, the switch cuts the power and the pump stops. The Sanei manual says the tank on an automatic pump is preset at the factory, so you do not need to refill it with air or water.

On the suction side, the end of the pipe in the well has a foot valve, which the Sanei manual also calls a thusen klep (the local trade name). This valve keeps the water from running back into the well when the pump stops, so the pump housing and the suction pipe stay full of water. On deep-well pumps, the Sanei manual says the foot valve should sit below the ejector, with the ejector under water.

With that in mind, the three main symptoms are easier to read. A pump that does not start means power is not reaching it, or a protector has shut the motor off. A pump that runs non-stop means the pressure never builds up. A pump that switches on and off by itself means pressure keeps escaping even though no faucet is open.

1. Check the power from the outside. Make sure the MCB has not tripped and the plug is in. According to the Shimizu PS-128 BIT manual, a broken or damaged power cable may only be replaced by the manufacturer, a service center or a qualified person.
2. Give the motor time to cool. The pump has a thermal protector that stops the motor when it gets too hot. The Shimizu manual says to wait until it cools down, about 20 to 30 minutes, before trying again.
3. Watch the voltage. The Shimizu manual allows plus or minus 10% of the rated voltage in the specification, and if the voltage is too low, it says to check with PLN, Indonesia's state electricity company. Lights that dim while the pump tries to start are a clue worth noting.
4. After a long time out of use. Dust and dirt from the water can harden in the pump head so the motor cannot turn. The Shimizu manual describes what to do: switch off the power, then turn the motor shaft a few times with a screwdriver or a similar tool, and the pump can then be used as normal.
5. If it still does not move. A motor that hums without turning, smells burnt or trips the MCB needs a technician. Do not keep trying to start it.

Start with leaks, because they are the most common cause and the safest to check. The Sanei manual names a leak in the outlet pipe as the first cause of a pump that keeps running even though every faucet is closed. A small leak you cannot see is enough: a dripping faucet, a tank float valve or toilet tank that keeps letting water through, or a pipe joint in the yard that is always wet.

1. Close every faucet in the house, then listen. If the pump keeps running, or starts now and then while nobody is using water, water is escaping somewhere.
2. Check the toilet tanks, the outdoor faucet and the float valve in the rooftop water tank. Shut off the lines you can close, one at a time, to narrow down where the leak is.
3. Check the suction pipe joints from the well to the pump. The Sanei manual stresses that suction pipe joints must be completely airtight, because a leak there weakens the suction or keeps the pump from drawing water at all.
4. If the pump keeps switching on and off, the Sanei manual lists several possibilities. The suction valve may be stuck or damaged, or the suction pipe may be leaking. Other causes are a tank with no air left in it, a faulty pressure switch, or a supply voltage that is too low.

In the dry season, the water level in the well can drop. The Shimizu manual says to check how deep the water is if the motor runs but no water comes out. It also says to allow for the lower dry-season water level when the pump is installed.

A surface pump needs its housing and suction pipe completely full of water before it can draw. The Shimizu manual describes the steps: open the priming plug on the pump, pour in water until the housing is completely full, put the plug back and close every faucet. Start the pump, wait until it draws water, then open a faucet partway. If no water comes out, there was probably not enough priming water, and you need to prime it again.

The Sanei manual adds that priming is only needed once. You repeat it only when the suction pipe has been removed, or when a leak at a joint or valve leaves the pump housing short of water. So a pump that has to be primed again and again is a sign of a leak or a foot valve that does not close; it is not normal.

One rule is in both manuals: never run the pump dry. The Sanei manual says this can burn out the pump's electric motor. The Shimizu manual also says not to run the pump above 40°C, to keep it out of direct sunlight and rain, and to stand it on a cement or concrete base about 10 cm high.

Contact the authorized service center for your pump's brand, or a pump technician, if:

• the motor hums without turning, smells burnt, gets too hot even with water flowing, or trips the MCB;
• the pump keeps running non-stop or cycling and you cannot find a leak in the house;
• the priming water keeps draining away, which usually means a problem with the foot valve or the suction pipe inside the well;
• water seeps from the pump housing around the motor shaft;
• the supply cable is damaged or the cable connection to the motor has to be opened.

Replacing the capacitor or the mechanical seal, repairing the motor, and adjusting or replacing the pressure switch are jobs for a technician. The switch housing and the motor terminals contain live electrical connections, and the capacitor holds a charge even after the plug is pulled. If a pipe has to be cut or rejoined, or the foot valve at the bottom of the well has to be lifted, that work is for a plumber or pump technician. The Shimizu manual also says the pump is meant to be hardwired and recommends connecting the power cable through a circuit breaker; that installation is a job for an electrician.