Viessmann boiler 100 fault code f4

This error is the most common out of all the other error codes, and it normally means that there is something wrong with the way that your water pump is functioning. If you have experienced this error code, it’s advised to contact a professional Viessmann engineer for help.

Some boiler faults can be diagnosed with a quick visual inspection of the boiler and its controls. Faults such as Incoming water temperature too low or Incoming air pressure too high may be identified by looking at the display and checking whether water flow is present in the incoming water gauge. With other faults, you will need to enter a diagnostic mode in two steps.

– First, turn OFF the power supply to the boiler for a few minutes

– Next, press and hold the UP button on Control Panel (first key from left) for 10 seconds

When a boiler has a fault code F4, it is usually due to a problem with the coolant level.

The coolant in the boiler is required to be at a certain level for the boiler to work. The coolant level can be checked by turning on the burner, then opening the access door and seeing where it should be. There is an error code F4 displayed if there is not enough coolant in the tank for the heat exchanger.