Code F4 fault. Boiler not firing. Have replaced ignition transformer code 063 but still not working, believe the faulty ignition transformer may have damaged PCB. Anyone able to offer help

Kieran Daly, December 2009

i have a 2006 100 and came home to no heat .
code f4.
removed the burner which has a lot of ash and re assembled . cleaned the electrode \re assemble and no difference . reset multiple times and it re starts . i am sure it will not start again without many resets.
i will call viessman

J DARMON, April 2018

I agree with Louis and think we should all band together and sue Viessmann!
They need to compensate all of us! I'm going to contact my Lawyer.
Joel from Canada

Joel, March 2017

i have same problem. But somehow different. When i open hot water, F4 fault appears. During heating, no problem. Service cleans ignitor and gas place. The problem seems to solve. But after 2 month, it appear again. How can fix it? Anyone can advise?

Okan, November 2016

Thankyou Andy for your answer. At last I've found a post on the net that seems to relate at least partly the same as my problem. I noticed that the carpet was wet under our vitodens 100 w. Took the case off and on shining a torch up to where the condense enters through the black grommet I noticed a crack in the plastic and condense was seeping out and running down the outside of the heat exchanger. I called out a viessmann engineer who put his analyser probe into the air intake and said there was mixing present. Filled out a immediately dangerous form and capped the gas supply. I have now ordered a new boiler flue connector hoping that this comes complete with the piece of plastic that needs replacing. I was told viessmann wouldn't warrant any flue part after 3 and a half years but see this as a design fault myself. Cheers, Phil ( retired due to health issues)heating engineer of 40 plus years.

Phil, March 2016

an update to my boiler and as to why that plastic air horn deteriorated, the rep from viessman said it was because exhaust gas was recirculating from the top of the combustion chamber back to the air inlet. There is a rubber grommet that was apparently leaking exhaust gas back inside the boiler box and then back to the inlet pipe. apparently it should be replaced every once in a while, mine is three years old and causing grief hope this helps someone.

Andy, February 2016

there is a plastic air horn right inside where the air comes into the gas valve/ mixing chamber and mine had the bottom quarter missing from deterioration of the plastic and so i took a piece of aluminum heat duct tape and formed it to cover the missing plastic and put the plastic air pipe back on and the boiler fired right up. this was after a considerable amount of trying every other thing to check, including a new ignitor and a new control board that a plumber let me try out but to no avail. the combustion chamber was also very dirty so it got a good cleaning also. This is just a temporary repair until i can get a new one from viessman. Hope this helps someone else out there.

Andy, January 2016

I have a friend who has one of these boilers, he told me:

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.

Joe the plumber, January 2016

I also need to continually clean the electrode contacts.The last time I left the unit cover off, and noticed a continuing ticking sound within the boiler, about 1 time per second. This happens when there is no call for heat, and the unit is not running.
When I power off the system, the ticking stops, so I doubt it is any expansion or contraction of the components.
Does anyone know if this sound is the spark phase, and should this be happening ? Could this be the reason the electrodes wear / need frequent cleaning?

Gord, October 2015

F4 fault and red reset light flashing. Had three local plumbers to look at problem, each failed and refused to come back. Then I contacted the manufacturer who sent their own heating engineer. They offered a £200 plus VAT fix all charge. The boiler was made 10 years ago but installed about 7 years ago, this made no difference and the manufacturer was true to their word and replaced loads of parts. The engineers were great, my feeling is only use the manufacture of this boiler for repairs and service. They know first generation Vitodens 100 boilers had some problems. So ring them up and get it sorted.

Ian Birch, March 2015

If your system is a gas system either natural or propane.
If your system was not set up properly which it sounds like it was not set up properly. Should have a company go out that has a combustion analyzer & can get a hold of viessmann and get the proper settings it should not soot up any more.
Also you should have a company do a once a year maintenance that will check the system for proper operation.
These newer high-efficiency systems are not like old conventional systems that don't need once a year maintenance.
Just make sure the company you have going out can do a proper combustion analyzer test on it and have the proper information for set up

John, December 2013

radiators don't get hotter than 17c.

magmao, December 2013

Our unit was installed 3 years ago. After 1 year, boiler shuts off with F4. Reset a few times, did not worked. Called our plumber and replaced the electrode. 4 months later, F4 showing up again. Sanded the electrode, cleaned and drained the plastic trap bottle. Boiler ran another week and F4 showed up again. Replaced electrode again and lasted another 3 months. This time while replacing a reconditioned electrode, I used a wooden popsicle stick to reach through the electrode hole into the combustion chamber and was surprised to be able to scrap out a lot of black residual. After that, the boiler ran for another few months and F4 shows up again. Open the electrode hole and found a lot of garbage in the combustion chamber again. This to me is a design problem with the Vitodens. It is obvious that the boiler needs to have the electrode, trap bottle and combustion chamber serviced every 4 months. This is what we have to do since. This is totally UNACCEPTABLE. After reading all the responses, it is clear that the problem is not with the manufacturing of a specific unit, it is a Viessman design deficiency which they should own up to it and rectify this problem for all of us.

Louis C, October 2012

second house we built using the system, not happy!!! 5000 sqft with 3 zones and runs our domestic water as well. Were using a good plumbing company to bad about their product . Same problem with both units f4 fault, had to completely replace the last unit . Dont know about this one yet. LAST TIME I BUY A VISEMANN!!!!

SUCKERED, April 2011

Thanks Chris for the pointer to frozen condensate pipes. Just had an F4 message, got out the towels and hot-water, and had it working again in a few minutes. Could hear lots of water and ice falling away down the pipe as it melted.

Alan, December 2010

I've had this problem this morning.

After reading these posts I went to the viessman website and found some articles about frozen condensate pipes. This is relevant for me as it was -12`C last night.

I found these two articles which may be of use to others getting an F4 error when it's so unusally cold:

http://www.viessmann.co.uk/etc/medialib/internet_uk/technical_updates.Par.84685.File.File.tmp/INDUSTRY%20GUIDANCE%20FOR%20HOUSEHOLDERS%20ON%20FROZEN%20CONDENSATE%20PIPES.pdf

http://www.viessmann.co.uk/etc/medialib/internet_uk/images/Press_releases/press_releases.Par.41402.File.File.tmp/Frozen%20condensate%20pipes.pdf

Chris, Yorkshire, UK, December 2010

had my viessmann 100 for 3 years now nothing but problems,f4 the main one, new pcb the only way to fix,had 4 NOW,something should be done.

TERRY, December 2010

In our three year old brand new house in Edmonton Canada we've had a lot of problems with the F4 coming on. We found out we have to keep cleaning the P-trap plastic bottle in the back of the unit as it gets very rusty from the moisture that comes from the combustion chamber. Also we have to sand paper the ionisation electrodes fairly often to keep the F4 from shutting down the system. Once we do both above it works for a few months.

George Williams, July 2010

had simmilair problem with unit,having to set rest but on f5 fault.
talked to sales rep and manufacture and have been given a replacement flapper in boiler unit.
Original flapper was getting stuck,this flapper stays partly open all the time.Part of purge blower system but inside boiler unit. We have also had trouble with falty ignitors.Takes some proding from manufacture to get componsation.Units are 2 years old and have been doing this since first heating season. Easy to install
This was on a gas boiler vitoden 100

Tom, May 2010

inI my manual it says fault is: Check ionisation electrode & leads, measure the ionisation current, check the gas combination valve, ingnition module and condensation drian.then press reset. aslo in service it says check burner gasket & burner gauze for damage,also the iginition ionisation electrodes. but to fit them they ned to tightened to a torque setting 2.5Nm. approx. and the gasket set too 3.5Nm. what ever this means. Hope this helps

steve, February 2010

I seem to be having the F4 problem too. I press the reset button only to find it cuts back off after a minute or two. I have not called Viessmann but really need to as I can’t keep this up having no heating or hot water at times. I’m wasting a hefty amount of water waiting for the temperature to rise, which is not a good sign when on a meter!

Can anyone advise me on how much its cost you for a PCB board before I ring Viessmann to get it sorted?

Cerys, February 2010

I have the same problem with the PCB giving up and am contacting Veissman again tomorrow to see what there answer is?

James, January 2010

Has anyone managed to find a number for Viessmann that is answered out hours and at the weekend?
I've been trying to get my supplier EON to come out but they just say that Viessmann aren't taking calls and I'm a bit fed up of looking at a condensing boiler (Vitodens 100) displaying F4.
So much for the 5 year warranty and promisses of 365 day coverage.

Within a few months of mine being installed it had to be repaired by Viessmann, new PCB, controller and wiring looms but the problem returns every time the exterior temperature drops. :-(

Camster, January 2010

Got mine installed less than 2 months ago..F4 keeps popping up, I hit reset only for it to fire up and within 2 mins F4 appears again! Im cold, no hot water.

N Turner, January 2010

I have the same problem with mine which is only 2.5 years old and have replaced the ignition module with a new black unit (mine was the old green one) but it has got pregressively worse and I have been told it now needs a complete new PCB board. Plumber coming out today to sort a price and get it ordered as its getting pretty chilly in the house and very annoying !!

Dave Youngs, January 2010