fault code f5 on Viessman Vitodens 100

[JohnD]

Mine had a F5 when i came back after 3 weeks hols yesterday

I pressed the Reset button and it started again.

I have a vague idea it might have done that on a previous holiday as well.

Looking at some other threads it looks like it is more prone to happen when the boiler is out of use. Obviously heating was off and very little hot water used while we were away (mine is the 100 Compact).

I like the sound of the new flap with a nobble to prevent it sticking. I am in a coastal area where sea spray helped my previous boiler to go rusty round the flue (that's why I went for the mostly-stainless Viessmann)

 

[mysteryman]

This flap was only fitted to Vitodens 100 type WB1A and 200 type WB2A boilers. There are gas safety issues in fixing it, but no new parts have to be obtained. These boilers were superseded in 2008 and 2007, and no current boilers have the flaps.

 

[JohnD]

The solution is to remove the rubber seal with a stanley knife!

is that the correct fix?

 

[Terry7556]

john that is exactly the advice given to me from the veissmann tech line guy i spoke to about the f5 fault

 

[Agile]

I dont think that Viess tech help should be giving advice on doing gas work to unregistered owners.

Was it Phil, Lee or even Hugh? Doubt Katie would have suggested that.

 

[Terry7556]

i could,nt agree more

 

[JohnD]

It happened again when I was away for a few days, won't reset now.

It is 3 years old.

It looks like a straightforward warranty claim to me. Any reason why not?

 

[simond]

Our customers all got 5 yrs warranty, so the flap has been fixed.

If yours was fitted under the two year Viessman scheme, it is of course at their discretion. I would ask them, nicely, when they are back in the office tomorrow.

Unfortunately, although it is a simple job, there is a fair bit of dismantling involved including removing the gas valve pipe and openingthe heat exchanger, making it non -DIY.

Keep the faith though, they are good boilers.

 

[JohnD]

I had the new part fitted today, f.o.c. under guarantee. I have a WB1A. I asked the installer if it was the same as the old one and he said yes. Does that mean in a few years the new one will stick?

 

[mysteryman]

This advice is for professionals only:

You can scrape away the rubber seal the flap sits on. New parts are not needed unless the hinges are broken. Check the flue duct going up from the heat exchanger housing to the flue turret. The gasket may have been displaced during installation. Check that it is not leaking flue products into the sealed casing. As Agile says, it may be a faulty air pressure switch, but that is extremely unlikely in actual fact. The main burner gasket is a good quality item, so doesn't have to be replaced each time unless it is damaged. The turning it upside down trick is for WB2A boilers only.

As I understand it, a householder may work on his own boiler if he is competent. No-one not Gas Safe registered may work on anyone else's boiler even for free. Not your Mum/Dad/bro/sis/son/daughter/uncle/aunt/nephew/niece/lover/mate/bloke-down-the-pub/anyone.

 

[JohnD]

just to check:

You mean that this fault will recur every few years because Viessmann are still manufacturing/supplying/fitting a part which is inherently defective?

 

[mysteryman]

No I do not mean that. As stated, the root cause of the problem is often a displaced gasket around the flue duct going up from the heat exchanger to the turret. They left the factory in place. They have not been used since 2007/8 for WB2A and WB1A boilers respectively.

The users of this forum would be helped better if useful advice were not countered by carping!

 

[JohnD]

I don't understand what you mean. This flap, that jams, is underneath the burner assembly, by the fan.

Is that the same thing you are talking about? Mine is a 2008 WB1A

 

[mysteryman]

Yes, the air flap is in the fan outlet. The root cause of the problem may be a leak from the gasket where the flue duct leaves the top of the heat exchanger. The problem applies only to WB1A and WB2A boilers.

 

[mickyg]

next time you get it serviced get the engineer to take it out. Its a pointless design fault and not needed.