Information on automatic domestic water pumps
In contrast to garden pumps, automatic domestic water pumps have a built-in pressure switch that switches the pump off after water is drawn off and switches it on again when water is drawn off.
A garden pump does not have this function. Some garden pumps have a safe-pump function, which automatically switches the pump off if there is no water flow, but does not switch it on again when water is drawn off again.
Definition of pump terms
The following illustration shows important terms relating to pumps.
Good to know: the pressure side starts in the pump and ends at each valve or shut-off device (tap) in your installation.
Possible causes of faults
If the automatic domestic hot water system does not switch off, this may depend on various causes. Observe the behavior of the automatic domestic water system using the symptoms listed below:
1. the automatic domestic hot water system switches on again and again briefly without drawing water: there is then a leak on the pressure side. The following section describes how you can locate and rectify the cause.
2. the machine does not switch off after you have finished drawing water? There may be a leak on the suction side or a defect in the pressure switch.
a. You can usually detect a defective pressure switch yourself on automatic domestic water dispensers that have an LCD display: The pressure should rise to the "MAX" value after water withdrawal has ended. If no pressure or only "MIN" is displayed, there is probably a defect in the pressure sensor. In this case, you should send the automatic water heater to us for repair. You can find more information on repair returns below.
b. If there is a leak on the suction side, the automatic domestic water system does not reach the switch-off pressure. Measure: Check all connection points and screw connections on the suction side and seal them particularly carefully.
Possible faults in the installation
Possible sources of faults in the installation are valves whose tightness is not obvious, e.g:
- Water inlet valves of toilet cisterns
- Inlet valves of washing machines
- Valves installed in pipes
If possible, disconnect these consumers from the water supply to the automatic water heater. If the automatic water heater then no longer switches on without you drawing water, the fault lies with this valve or one of these valves.
A shut-off valve installed on the pressure side immediately downstream of the automatic domestic hot water system is helpful here in order to be able to disconnect the entire installation from the water supply.
- If the non-return valve in the automatic domestic water system is responsible for the fault, you can remove it as described.
- If the non-return valve is not responsible for the fault, you must check every valve in your installation for leaks in order to eliminate the fault.
Possible causes, valid for the following automatic domestic water heaters:
4000/4i - item no. 1481
4000/4ep - item no. 1481
4000/5i - item no. 1483
4000/5ep - item no. 1483
5000/4i - item no. 1485
5000/5 Inox i - item no. 1487
4000/4 LCD - item no. 1763
4000/5 LCD - item no. 1765
5000/5 LCD - item no. 1767
6000/5LCD - item no. 1769
The non-return valve of these automatic domestic water heaters has a built-in spring. This spring closes the valve when no more water is drawn off.
Contamination such as sand / limescale can cause this valve to leak. A defective or missing sealing ring (O-ring) can also be responsible for the leakage.
Instructions for removing the built-in non-return valve.
Set or leave the rotary switch to RUN.
- Pull out the mains plug
- Make sure that the pressure side is depressurized, e.g. by opening the tapping point!
- Close any existing shut-off devices on the suction and pressure side.
- Loosen the screws counter-clockwise until you can slide the holder upwards and backwards into the bearing groove.
- Remove the cover of the integrated non-return valve by turning it counterclockwise.
- Remove the valve body and clean it under running water.
- After cleaning, insert the valve body in the correct position and centered (cone tip pointing downwards).
- Screw the cover back on as far as it will go.
- Push the holder forwards and position it in its original position. Then tighten the screw clockwise.
Possible causes, valid for the following automatic domestic water heater:
3500/4E - item no. 1757
A non-return valve with built-in spring is used in this automatic domestic water heater. The valve is also closed by the spring when no more water is being drawn off.
The valve can become leaky due to contamination such as sand or limescale. A defective or missing sealing ring (O-ring) may also be responsible for the leakage.
Instructions for removing the built-in non-return valve
1. switch switch (11) to O.
2. unplug the mains plug.
3 If necessary, close all valves on the suction side.
4. open all tapping points so that the pressure side is depressurized. Then close the tapping points again to prevent the connected pipes from running empty via the automatic domestic water system.
5 Unscrew the cover (14) of the non-return valve using a suitable tool.
6. remove the valve body (15) and clean under running water.
7. refit the non-return valve in reverse order.
8. restart the automatic domestic water system.
Possible fault after a long period of non-use
Before commissioning after a long period of non-use, pull the piston (k) on the non-return valve several times.
Possible causes, valid for the following automatic domestic water heaters:
4000/5E - item no. 1758
5000/5E - item no. 1759
6000/6E - item no. 1760
smart automatic water heater 5000/5 Art. no. 19080
There is no spring in the non-return valve of these automatic domestic water valves. The valve closes automatically when no more water is drawn off. The non-return valve can remain open if it is dirty. When removing and reinstalling, check whether the non-return valve closes automatically. The cone of the non-return valve must fall slightly to the valve seat of the pump. The valve can also become leaky due to contamination such as sand or limescale. A defective or missing sealing ring (O-ring) may also be responsible for the leakage.
Instructions for removing the built-in non-return valve.
1. switch switch (11) to O.
2. unplug the mains plug.
3 If necessary, close all valves on the suction side.
4. close all tapping points again to prevent the connected pipes from running empty via the automatic domestic water system.
5 Unscrew the cover (14) of the non-return valve using a suitable tool.
6. remove the valve body (15) and clean under running water.
7. refit the non-return valve in reverse order
8. restart the automatic domestic water system.