Viessmann Vitodens WB1B Fd fault

[LL]

Hello hopefully someone can help with our boiler problem.

We have a recurrent Fd fault with a Viessmann Vitodens (WB1B 100-W) boiler. Context of our system below:

We are living in a 7 year old house which previously had a faulty glow worm boiler that failed on day 1 of moving in.

Last November we had a new Viessmann Vitodens (WB1B 100-W compact 19kw regular boiler open vent) fitted by a local Gas Safe registered engineer. We have a closed system, micro-bore plastic piping, S plan system, unvented cylinder, grundfos pump. A magnaclean filter was fitted when the boiler was installed and is not picking up much gunk.

After the boiler was fitted unfortunately the timer, thermostat and CH pump all died. We had a BG hive system and new grundfos Alpha pump fitted. We also had a sticking motorised valve replaced.

Over the last 3 weeks we have had 7 or so engineers visit. 5 from British Gas as part of our maintenance contract and 2 from Viessmann.

A faulty Hive thermostat was changed, and the system reset. Hive is now working fully.

The boiler after running for a while will shut down and have a flashing Fd sign on the display. It will not reset and will only switch on again after being off for a few hours.

This is linked in the manual to faulty electrodes - these have been tested - or to a faulty main board. Viessmann have changed this twice.

British gas have been fantastic at trying to diagnose the issue. The latest senior engineer fitted a different bypass valve as he suspected the boiler was overheating - this has improved the problem but it is still an ongoing issue, particularly on a Sunday night after it has been used more over the weekend.

The condensate pipe appears fine, we have checked for blockages and freezing problems. It is draining out ok.

We are totally unsure of which direction to turn. Viessmann are being no further help and British Gas are trying to keep pushing them (they are being fantastic) to help find a resolution. We have taken so many days off work and spent hours e-mailing and calling to try to get to the bottom of this.

Has anyone else seen this Fd issue on this type of boiler? When I switch it off/on it says on display 171, then 117 deg then Fd flashes. It takes a few hours of being off before it will successfully fire up again as normal.

I am considering a power flush or a powder flush in case this is a flow issue. From research I have seen that power flushes do not work as well with micro bore plumbing - is this correct? Has anyone heard of powder flushing being successful? Could there be crud in the heat exchanger causing an issue?

I am also considering changing the magnaclean for a
FERNOX TOTAL TF1 COMPACT 22mm which will trap more than the magnaclean which is magnetic only. Any thoughts?

Many thanks

 

[Dan Robinson]

I am also considering changing the magnaclean for a
FERNOX TOTAL TF1 COMPACT 22mm which will trap more than the magnaclean which is magnetic only. Any thoughts?

TF1's are a total pile of leaky warnk.

I'm not allowed to comment of PowDerflushing here .

The boiler is still under warranty so keep going on a Viessmann until they get it sorted. However, having a filter on the system doesn't negate the requirement for the system water to be clean in the first place.

These heat exchangers are relatively easy to clean without the need for snake oil.



Ahem.

 

[LL]

Hi - thanks for your reply

Could you suggest a different magnetic cleaner that might be better than the magnaclean?

If there is crud in the heat exchanger how could I get that cleaned?

Have you seen this kind of error before?

Thanks

 

[Agile]

Although you have described the problems quite well there is no substitute for actually being there at the boiler.

I had better not comment on Powder Flushes or I might end up like Dan!

As he says, keep on at Viessmann and get them to diagnose the fault after all its their boiler and they should be able to work it out!

Even if its not caused by the boiler, they should be able to work it out so you can get BG to sort it out.

Having said that, microbore is NOT the best system for modern boylers.

Have no one questioned or even changed the flow temperature sensor? Or even the ignition module?

Tony Glazier

 

[Dan Robinson]

Magnaclean is about the best.

Guardian and BoilerMag are respectable alternatives.

Not seen this error, but largely because I don't have to work on many 100 series Veissmanns. Thankfully.

Seems a delightfully vague error code doesn't it.

 

[Agile]

First time I have seen "boilers" spelt "boylers" !

Most of the magnetic filters are somewhat OK. Thats not the cause of your problem.

The boiler does not know what kind of filter you have!

Tony

 

[Plumbkinobi]

Try a higher rated pump at a guess you've a 15.50 installed try a 15.60 or even an 8 meteter head pump, there are a lot of restrictions in a microbore system, how old is the system?

 

[Plumbkinobi]

Fitting a filter will not help you, will only clean magnetic particles in the water, that does not sound like your problem

 

[LL]

Thanks guys
I currently have viessmann pointing finger at system issue and saying nothing further they think is wrong with boiler
BG saying system appears fine given changes boiler shouldn't be showing error. They are being very supportive and pushing Viessmann

Boiler was installed Nov 14 system is 7 yrs old from when house built.

 

[LL]

Normally the boiler will fire up when I reset in morning (presumably once it is cool again if it is overheating). This morning it would not come off this code.

Turning hot water and Ch on/off it sounds like the motorised valves are moving, tried giving them a giggle, pump is not switching on,

At end of my tether with this

 

[muggles]

With all those electrical issues I'd be inclined to get an electrician in to do a full check your wiring - that's quite a lot of things going wrong in a short space of time

As for filters, stick with what you have - Magnacleans are far superior to TF1s. I've got a boiler engineer friend who had a TF1 and a Magnaclean fitted in series for a while - TF1 first, Mag second. The Magnaclean still caught more muck despite the system water passing through the TF1 before it hit the Mag.

 

[Agile]

A good boiler engineer will fully understand electrical problems.

Problem is that you are stuck with BG as your contract is with them.

Just keep pushing them! They took it on contract and its up to them to sort it.

They have the skills across their staff but getting the right person there is another problem and particularly if they will not admit its a boiler problem ( which I think it is! ).

Tony

 

[D_Hailsham]

This is linked in the manual to faulty electrodes - these have been tested - or to a faulty main board. Viessmann have changed this twice.

The fault is also linked, in the manual, to electrical interference.

How close is the Hive receiver to the boiler?

It might be worth temporarily disconnecting the Hive and using a wired thermostat to control the boiler. This will eliminate the Hive as the cause.

 

[Agile]

Yes, it could always be the bees in the Hive are causing the problem!

 

[LL]

Thanks all - actually BG engineers have been really good and one of the Viessmann engineers (sub-contracted) was helpful too.. but Viessmann customer services is a bit disappointing. BG are trying to arrange an appointment for both engineers to attend at the same time but Viessmann are not being great about getting back to them...

As the boiler was registering 115 deg C this morning when it couldn't have been, they think it could be a faulty flow temp sensor in the boiler... we will see...