In automatic domestic water heaters, the built-in flow sensor ensures that the pump switches off when no more water is being drawn off. The flow sensor consists of a small impeller, among other things. If the impeller is dirty or blocked, no more flow is detected and the impeller should be removed and cleaned.
For automatic domestic water heaters / automatic home & garden water heaters from 2015 onwards, you can find out how to remove the impeller under Cleaning the flow sensor in the operating instructions.
For automatic domestic water heaters up to 2014, proceed as described below for cleaning:
- Disconnect the mains plug
- Depressurize the pump, open the pressure side (water tap), turn the rotary switch to the "Start" position, open the drain plug (no. 6 on the drawing).
- The flow meter (impeller) is located between the carrying handle (30) and the swivel outlet.
- Place the pump in front of you with the electronic display facing you.
- In the motor housing you will find 3 Phillips screws in the top row and 2 Phillips screws (1) in the 2nd row. Please loosen these.
- Now you can carefully bend the housing halves apart at the top.
- With 2 additional screwdrivers, which you insert between the motor and the housing halves, you can fix the housing halves so that they remain open.
- Now look into the open pump from above. There is a round cover (35), which is screwed on with another 5 screws (33).
- Remove these 5 screws to open this cover.
- You can then carefully lift the cover with a small screwdriver and remove it.
- Now you can see the impeller (38), which measures the water flow rate. This must run smoothly on the stainless steel shaft.
- Please clean the impeller housing, the stainless steel axle and the impeller so that it runs smoothly again. The ring-shaped magnet in the impeller may also have lifted. This must be flush with the plastic holder. If this is not the case, you should push the magnet back in.
- The impeller must be reinstalled in the pressure switch with the magnet facing upwards (towards the cover and therefore the sensor).
For the sake of completeness, we would like to point out that such repairs to electrical parts may only be carried out by a qualified electrician. We accept no responsibility or liability for repairs not carried out by us.