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
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