Viessman boiler

[olddiyman]

Hi Chaps

I have a problem with my 4 year old Viessman Vitodens 100 WB1A.

My boiler was not getting very hot and kept shuting down. F4 fault. I called a Viessman approved engineer out who said it was probably due to a sludge blocking the system and went through checking the pump and circuits. Did not check anything on the boiler itself.

As I have had all of the rads off in the past few years to decorate and flushed the system 2-3 times I could not see this being a big issue.

After 2 hours he left with the system running and doing OK. However during the first night when the system shut down it failed to start. F4 again.

I managed to get it going using a few points that the engineer told me. I have left it running all the time now as I know it will not start when shut down.

For a week now the boiler reaches 65deg and runs for 2-4 hours but then the flame drops and the temperature drops but struggles to start again. Sometimes it does and sometimes to does not. Plenty of clicking. When it does start thers a bit of a "bang" in the boiler as it fires up.

When its going the rads are nice and hot and boiler runs smooth with little noise.

Any idea what this might be.

 

[mickyg]

I thought F4 was an ignition fault on these?? thats got diddly squat to do with the flow..
the old ones had issues with the igniton module as well, maybe your problem.

 

[olddiyman]

Thats what I thought so I replaced the ignition unit but it made no difference.

 

[Boilerman2]

No Comment from "Mysteryman" i see!!!

 

[olddiyman]

I replaced the ignition unit with a black one as you suggested mysteryman. Read that on previous forums. OK looks like pcb which is what I was hoping it wasnt. Looks like £200 then. I think Viessman call out is £190.

 

[Agile]

There is something wrong if the Viessmann listed engineer did not know what F4 meant!

If its a black ignition unit they are unlikely to be the problem. However the first thing to check which is easy is the ignition gap between the electrodes. That should be done by a gas registered engineer but the risk is small as long as the gasket is checked to be in good condition.

Then the boiler should be checked with a gas analyser to see if the mixture is correct.

It might be the PCB but those things are simple to check first before embarking on replacing an expensive part.

There seems something wrong when a boiler company charges us as much for a PCB as they charge our customers to send their own engineers there to replace it!

Tony

 

[olddiyman]

All sorted, nice and warm house at last.

It was the pcb. My Viessman engineer called round yesterday to strip and check the boiler settings. Found electrical output from pcb very low. Not sure of the exact technical term. He obtained a quote for the pcb part but I gave him contact no for viessman spares direct and saved £40+. Arranged a next day delivery and he called in today and fitted the unit and left with it all ballanced and running smooth. Noticed straight away how it fires up so quiet without all those clicks.

Thanks for your advice and comments.

 

[simond]

Never seen a WB1A with duff ignition electrodes.

Plenty of ignition modules and a large incidence of failed PCBs giving duff ignition at around 4yrs old.

Good reason to get an installer with a 5yr warranty

 

[Agile]

I have not seen any seriously wrong ignition electrodes on that model ( on many others though. ).

However, I would always check that first to be sure. If I didn't then I could end up with an over priced PCB in stock and as I would always offer a customer the cheapest solution of getting a Viessmann fixed price repair then I would have it in stock for a long time!

I know that most others would just charge for the new PCB and then adjust or replace the ignition electrodes. I am not like that though.

Tony