Possible cause 1: It is mounted pressure reducing valve, water meter or tight setbackvalve on the main water intake of the residence. Alternatively, the cold water pressure is in the home too high during the day.
Solution: Install AX expansion tank which takes up expansion during heating and mounting / adjusting pressure reducing valve for stable water pressure into the home. Pressure reducing valve adjusted in relation to the expansion vessel preprint  (usally 5 bar). Contact authorized installer.

Possible cause 2: The heaters safty valvel is worn or there are particles between membrane and valve seat due to unclean water.
Solution: try to flush through the savfty valve with water. Open the valve for about 1 minute. If the valve is stil dripping after closing the valve must be replaced. Contact authorized installer.

Possible cause 3: leakage by electric heating element.

Vertify by:

1. Break electrical supply
2. Unscrew the lid in front of the electrical exchange
3. Visually check if the leak comes from the heating element.

Solution if YES: change gasket / heater. Contact authorized installer.

1. Possible cause 1: The power supply to the water heater is broken.
   Solution: Vertify by:

   1. The fuse is in the fuse box
   2. Plug from the heater is plugged into the wall socket
   3. Including plug (earth) has not broken out in the fuse box

   Possible cause 2: The electrical thermostat has turned out for security function.
   Solution: Press the “RESET” button on the safety thermostat.

   1. Disconnect power
   2. Disassemble the electric lid with a screwdriver.
   3. Press the red “RESET” button.

   Possible cause 3: The thermostat DHW is defective.
   Solution: Replace heating element. Contact authorized installer.

   Possible cause 4: Leakage on hot water pipes in the property

   Veritfy by: 

   1. Shut off mixing valve
   2. Wait 3 hours while the heater warms water.
   3. Touch the mixing valve to see if it is hot

   If YES, there is leakage on hot water pipes or other leaks.
   Solution: contact authorized installer.

Probable cause is that there is a lot of consumption of hot water in the home. (If the heater is the problem, it is not the hotwater).

Solution 1: Adjust the temperature on the thermostat to 80°C.

1. Disconnect the power supply
2. Disassemble the electrical lid with a screwdriver.
3. Mount the electrical lid before connecting the power supply.

Solution 2: Change to a larger OSO hotwater heater. Contact authorized installer.

Possible cause 1: The mixing valve on the heater is set to low temperature.
Solution: adjust the temperature on the mixing valve:

1. Twist the adjustable wheel completly against“+”
2. Then, twist the wheel against “–” until wished temperature (see the products installation instructions)

Possible cause 2: The electrical thermostat is set to low temperature.
Solution: adjust the temperature on the thermostat to 80 °C.

1. Disconnect the power supply
2. Dissemble the electrical lid with a screwdriver
3. Adjust the temerature on the thermostat with a screwdriver.
4. Mount the electrical lid before re connecting the power supply.

Possible cause 3: There are estimates in the crane (s) from cold water to hot water (suddenly cold or hot water in the crane).
Solution: contact authorized installer.

Possible cause is incorrect on the heaters’s electrical system.

Verify by:

1. Break electrical supply

2. Unscrew the electric lid in front of the electrical central

3. Check visual electrical connections in the box for any problems

If YES, contact OSO or authorized electrician for inspection or remediation. Fit the electric lid.

Often this occurs because there are long pipes (distance) from the hotwater heater to the drainage point. 

Solution: Mount a hotwater circulation cord or an electrical heatcabel on the hotwater pipe. Alternatively a heater (for example OSO NANO) can be mounted by the drainage point. Contact authorized installer.

The “hammering” comes from a sudden pressure increase when the tap closes quickly and is completely normal.

Solution: Mount an expansion vessel if the problem persists. Contact authorized installer.