Viessmann Fault F6

55Trucker

Hi everyone, and Happy New Year. I have a Viessmann Vitodens 100 combi boiler. This morning the heat was off and fault code F6 was displayed. I went to the Viessmann fault checker website and F6 is listed as a common code to all boilers, and it means "Fan not at standstill / plug-in connection".

Does anyone know what this means, and how to fix it?

GGross

The F6 error code does not appear on Viessmann fault code checker for the vitodens 100 boiler, checking the B1HA model book it is also not listed as an error. What is the specific model of vitodens 100, and can you take a picture of the error code? and is this boiler a US model?

On the fault code checker F6 is for a few model boilers, various errors associated, one model is a temp differential error, and several others are gas errors. Which fault code checker did you use and can you take a screenshot of what you entered?

55Trucker

Thank you for responding. This is the checker I used: https://viessmann.co.uk/en/support/fault-codes.html

Here is a picture of the fault display:



And this is the unit's data plate. I'm not sure if it answers all of your questions:

GGross

Ok that is not a fault F6 rather that is a fault 0b (zero Bee) If you look to the left of the display you will see a pressure gauge, the boiler has detected a low flow condition which is often the result of low boiler pressure, when it gets low enough, or enough air enters the system the flow will be slowed/stopped. The boiler requires a certain flow rate to fire, this is a safety. Standard residential boilers are generally filled between 12-15 PSI, 18PSI for 3 story. You may have something as simple as a slow leak that has let pressure off the system, I have seen these run in acceptable manner even while at 0 pressure on occasion, but they will eventually give you this code. The simple solutions here, make sure the pressure relief has not been blowing off, refill the boiler to the correct pressure for your system. When adding fluid there are some things to be aware of (boiler off, be careful of system water may be hot) If you are uncomfortable doing this yourself you may call for service, they will know what to do to fill the system. It is sometimes a wise move to check the charge on the expansion tank at this point as well.


0B

Vitodens 100-W, B1HA / B1KA

System behavior
Burner blocked.

Cause of problem
Low water, pump, flow switch defective.

Corrective measures
Check water pressure; Check the circulation pump, flow switch.

55Trucker

Thank you for the help. This problem actually is on my son's boiler. After providing him with this information, he found that one of the valves near the boiler was shut. I'm assuming it is the one on the boiler fill line. It turns out he had a plumber come in last week to fix a leaking Pro Press fitting on one of his radiators. When he opened the valve just now the system started working again. He says he never touched the valve himself, so my guess is that the plumber did and forgot to reopen it after the repair.

GGross

If the valve is on the fill line, I would suggest that your son close the valve once the boiler is topped up on pressure. This way he can monitor the system over the next few weeks to make sure it is not still leaking. The fill valve is a handy thing to have in place, I just personally prefer to know if my boiler is taking on makeup water, because then that means I have to find a leak!. Hopefully everything goes well, let us know if there are any other issues