Water pumps for motor homes and caravans
Washing your hands, cooking, washing dishes – as soon as you open a tap in your caravan water has to flow. But for this you need a water pump. Simple submersible and more complex pressure water pumps are both used in camping. They differ in terms of function, performance and price. Read here about the advantages and disadvantages of the different water pumps.
Submersible water pumps
In most caravans, submersible water pumps ensure that the water flows. These pumps are simply suspended in the water tank and, with a 12 V motor, they pump the water from the tank to the points of consumption. When you open a tap in your caravan, a micro switch starts the pump.
- Easy to install as the pump is suspended directly in the water tank
- Very few breakdowns caused by small dirt particles in the water
- Runs quietly
- Relatively inexpensive
- Won’t freeze if the water tank is emptied in good time
- Not especially durable
- The complete submersible pump has to be replaced when it no longer works
- It can take some time for water to flow from the tap, as the pressure has to build up first
How a submersible water pump works
A submersible pump consists of two chambers: the first chamber contains the electric drive motor, which drives an impeller. Centrifugal force ensures that the impeller presses the inflowing water into the second chamber. This is where the pumping pressure builds up and presses the water into the connected pressure pipe.
Power input and pumping capacity
Submersible pumps can build up a water pressure of 0.5 to 2.1 bar and pump between 10 and 25 litres of water per minute. If the pipes between the tank and points of consumption are very long, you will need a more powerful submersible water pump, for example, with two motors or a booster pump. This is integrated in the water pipes outside the tank.
Replacing a submersible water pump
Submersible pumps are designed for several hundred hours of operation. As the live parts of the water pump are welded into a waterproof plastic housing, individual parts cannot be repaired or replaced. If the pump breaks down, you need a new one. It may be worthwhile to have a spare pump just in case your pump breaks down while you are on holiday.
Tips for using a submersible pump
- Do not let it run dry by having too little water in the tank or by the pump not beeing properly suspended in the tank. To ensure this, you can install separate dry run protection. The small module detects when the pump motor draws more current when it is running dry and interrupts the power supply to the pump. This prevents damage caused by overheating.
- Regularly clean the pump pre-filters that capture suspended matter in the water.
- Before frost occurs, remove the water pump from the tank and empty the tank completely.
Pressure water pumps
Pressure water pumps are often installed in larger motor homes. A pressure pump is integrated in the water pipes outside the water tank and constantly keeps the pipes at a defined pressure. When you open the tap, the water pressure in the pipe falls. This is detected by a pressure switch in the pump, which then switches on the pump. Water flows from the tap with no long waiting times.
- Water flows immediately and evenly when the tap is opened
- Less prone to overheating than a submersible pump
- Depending on the model, can be installed several metres away from the tank
- Durable, as individual parts can be repaired or replaced
- Loud operating noise possible
- With even a small leak in the piping, the entire water tank can be pumped dry and the water floods the vehicle
- Much more expensive than a submersible pump
How a pressure water pump works
From a technical aspect, a pressure pump is a diaphragm pump. Up to five diaphragms are installed in the bottom part of the pump. Above these are the inlet and outlet valves. The 12-V electric motor moves the diaphragms back and forth very quickly. This creates a vacuum. The water is then sucked in through the inlet valve and pressed towards the outlet valve with excess pressure.
Desired pumping capacity
Pressure pumps pump up to 19 litres per minute at a pressure of about 5 bar. They are not only more powerful than submersible pumps, but also more durable. This is reflected in the price of a pressure water pump for your motor home or caravan. However individual parts, such as the diaphragm set, valves, pressure switch and pump head can be replaced easily.
Tips for using a pressure pump
- Because of the noise, make sure that you install the pressure water pump far enough away from the sleeping area.
- A pressure pump with rubber bearings does not transmit vibrations as much, which makes it quieter.
- Adjust the pressure in the pump to suit your piping.
- When you leave your vehicle, interrupt the power supply with a separate main switch for the water pump. The pump will then not start unnecessarily.
- Check regularly for leaks in the caravan piping. If the pressure drops, the pump starts: water flows from the leak and throughout the caravan interior.
- Empty the entire water system before parking your caravan or motor home for the winter, as pressure pumps can also be damaged by frost.
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