Just downloaded this.
F4- in 75% of cases is because no one has removed the burner, and cleaned the the accumulation of ash from the heat exchanger with a vacuum cleaner, and plastic brush and a few litres of good old tap water. The ash will look like coffee grounds and will slowly build up starting on day one. The ash will eventually interfere with the combustion process (this is an F4fault) Cleaning each heating season is recommended service in the operating manual. If left most boilers will eventually reach an f4 fault in year 2-4, depending how much dust the boiler sucked in during construction, and the size of house and how much domestic water is being produced for the family's needs. Fortunately this brand of boilers are super easy to clean and were designed to facilitate easy service.
Cleaning the heat exchanger takes about 45 mins tops, start to finish. Just like an oil change on your car.
If your tech isn't specifically familiar with these boilers don't hire them. Cleaning the glass on your gas fireplace will take longer.
Also change the ignitor and the ignition transformer if it's beside the ignitor electrode after a few years, they are very inexpensive, as most replaceable service parts for this boiler are.
F4- In 24% of cases the boiler is sucking in its own exhaust. This is because the vent is not installed with a proper adaptor at the top of the boiler or not piped square or plumb into the top of the boiler or perhaps a black rubber vent gasket at the top of boiler is dislodged from the stainless heat exchanger because the vent is applying pressure or force on the boiler.
Additionally, the fresh/ combustion air could be sucking in air from the boiler's exhaust vent outside the house. This problem will usually occur close to the install date, and may continue until the vent is corrected. Keep in mind the exhaust vent piping is supplied and purchased and assembled by the installer completely separate form the manufacture of the boiler, similar to the rest of the boiler room piping. Skill and understanding of gas boilers and vents seem to vary with installers. I'm pretty sure Viessmann even offers free training to any trade person the training is probably called " Academy" Why wouldn't you take free training if your a service person? I wouldn't hire a dentist who hasn't done a filing before mine.
With the exhaust gas its kind of like if you divert your car's exhaust with a pipe into the engine air intake- you would expect engine problems. (Its not rocket appliances)
F4 the last 1% - low gas pressure, flooded (water) in gas valve due to extended lack of service interval, electrical interruption while boiler is running, poor power wiring connections that arc in the connectors, extreme dust, paint spray, and finally water spilled on control console during cleaning. construction site or temporary generators that are not invertor technology
Could a home owner clean their own boiler?
Can a person change a tire or change their oil?
The car manufacturer has pretty specific info on how to jack up the car, check the manual, sometimes there are pictures too. It carries responsibility.
Most home owners are not aware of the need to have a periodic service to modern condensing boilers, and it often leads to a service call for no heat by a well meaning service person who just isn't familiar yet.
All brands of boilers need some cleaning at some point- the question is if they were designed to accommodate that service easily, if not service life will be reduced. Stay warm
