Viessmann Vitodens 200 Combi - screeching and 'F5' cutout

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I'm in a rented property with a Viessmann Vitodens 200 boiler which I think was installed in 2005 - it's driving me mad (and the landlord too!). As far as I can make out this is supposed to be a great bit of kit but it seems to have unsolvable faults.

I moved here in June, there were problems getting the boiler signed off then for the lease as it kept cutting out with an 'F5' error. I believe it was cleaned up internally and then seemed to function OK throughout the rest of the summer until, maybe October, the F5 errors returned - I think this is related to a flap valve inside getting stuck shut, the air pressure switch was replaced and it worked OK for about a week and the started cutting out again. About this time it started intermittantly emitting a high pitched screech, which to me sounds like a very loud old fashioned TV test card, bit like a 1KHz tone, if that makes sense. This noise is so loud it's waking up the neighbours.

The landlord's heating guy has looked at it, he and seems mystified (don't think he's a Viessmann expert), he's spoken to Viessmann technical who seem difficault to get hold of and vauge about what the issue might be - they suggested replacing a doughnut shaped component made of some sort of heat resistant material that fits around the burner, the existing one was coming apart which I don't think is supposed to happen. This made precisely no difference, the latest from Viessmann is that there are some modified parts for the flue which may cure it. Condensation from the flue has been mentioned as possibly being responisible for the F5 errors too.

Are any Viessmann gurus reading? The landlord is now talking of ripping it out - I want to give it a second chance as they're supposed to be top quality german engineering aren't they???
 
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cant help with the fault but ive only seen one viessmann and i wasnt impressed at all. it certainly didnt live up to its hype.

couldnt blame the landlord for ripping it out, even if you got something less reliable at least if it was a popular model there would be decent tech help and good parts availability.
 
anyone with more experience of Viessmann?

Thanks!
 
check the viessmann website for an approved engineer in your area. f5 is an easy fix if you know what your doing. the 200 is a great boiler.
 
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I also agree the 200 is an excellent boiler and it only needs a competent engineer to solve the problem.

Usually the F5 fault is just the fannyflap sticking and thats easy to deal with by convertin g it to the format of the later boilers.

Tony
 
Update - I've now had several visits from a Viessmann engineer, the F5 issue appears resolved and the engineer is adamant it won't reoccur, I guess this is down to the flap being replaced as I found the old one on top of the boiler.

But it's still deafening the neighbourhood with the high pitched screeching noise, sounds like resonance - not unlike what you get when rubbing the rim of a wine glass except head piercingly loud – can be heard three streets away. The engineer has not seen this fault before but one of his colleagues recons a descale will solve it. Unfortunately I've got to wait up to a fortnight for this guy to come and do the descale - apparently if that doesn't solve it Viessmann are going to replace it.

How likely is the descale to solve it and why would a four year old boiler need a descale?
 
Also, forgot to mention - system seems to be losing pressure quickly needing a topup from the mains to get to 1.2bar every few days. Is that likely to mean whatever internal pressure vessel the boiler has is shot too and could it have any bearing on the noise problem?
 
It sounds as if you had a nupty engineer!

Did he use a flue gas analyser to check the combustion conditions?

Thats an expensive looking instrument with tubes going towards the top of the boiler?

The first expectation is that the settings are wrong!

I presume your landlord does not have it serviced ( an Gas Safety check is NOT a service! )

Tony
 
Hi Agile,

No it has been serviced and is certified, etc. Landlord's heating guy wanted to condemn it as he couldn’t get the combustion correct. Since then the Viessmann guy (actually a sub contractor) has been at least three times - one of the things he has apparently done is update the software to correct the incorrect burning and I'm told the flue gases are now OK.

Everything works except for the noise. Landlord has just been onto Viessmann and we've got one of their own engineers coming next week as the other guy was starting to sound like he was doing deal with his mate for the descale (£350) which wasn't even guaranteed to be the solution.

I'm no boiler expert but having just had a look at it whilst it's busy deafening the neighbourhood my guess is the noise is definitely connected to the flue or fan - if I blow into the exhaust monitoring hole covered with a rubber cap the noise stops momentarily.

PS, any thoughts on the pressure loss?
 
You may think this is flue or fan!

I think its an incorrect mixture!

If you wanted to, you can access the flue then cover HALF of the outer inlet holes and see if that stops the noise by strengthening the gas/air mixture.

Whatever you do do NOT breath any of the exhaust gasses and only do this at arms length.

There could also be a faulty joint in the flue.

The actual cause is not relevant to you as a tenant as its your landlords responsibility but it seems that he may have had some less than competent/honest engineers involved.

Tony
 
Thanks Agile

Perhaps you're right - the one thing I'm sure of is I'm fed up with it! And the neighbours too. So far we've had the Landlord's guy - a bonified heating installer with all the badges but not a Viessmann expert and the Viessmann supplied contractor (as it transpired it's still in warranty) so not amateurs. I find it hard to believe that so far no one seems to have any clue what is going on - hence why I'm left to make my own best guesses!
 
You would be surprised at just how INexpert many gas people can be. Even some of the Viessmann service agents!

The payment for warrantee repairs is so poor than many of the better engineers will not do it for so little.

Try what I suggested if you feel inclined. It will make little difference to you but would help me to know if I have been able to guess what may be the problem.

Tony
 
If the Landlord does to decide to rip it out please give me a call and I will take it away for him. ;)

Tim
 
Hi Agile

Have just tried what you suggested - covering half the flue intake with a rolled up towel has no effect, however momentarily wrapping the rolled towel around the whole outer intake (leaving the central exhaust outlet uncovered) does cause the noise to pause briefly - but then I must be starving the boiler of any air so maybe not surprising. Does this fit in with your theory? Anything you think I should tell the next guy who comes out that might save us all some time? This next visit, hopefully some time this coming week will be Viessmann’s own guy.

As it's still under warranty if it gets ripped out it will be by Viessmann to replace it - no doubt they will take it away so no need for any other generous offers!!!
 
how long is the flue? did the engineer check the flue was sound? check whats been done with the flap with whoever did it, its a gas/air problem of that im sure.
 

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