Viessmann Boiler 0b Fault Code
The Viessmann fault code 0b relates to the burner switching and here we have Q & A or require an engineer for an emergency boiler repair.
The Viessmann Boiler Fault Code 0b Error Common Q & A
Just below, we have a list of common questions relating to the 0b fault code on the Viessmann Boiler.
- What does the 0b fault code mean on my Viessmann boiler?
- What are the likely causes of the 0b fault code being displayed?
- Can the 0b fault code be fixed on a DIY basis?
- Would a reset help to fix the problem with my Viessmann boiler?
- How does a burner get blocked, and how can this affect the boiler?
- Can a burner’s jet be unblocked, or will it need to be replaced?
- If my burner needs to be replaced, how much will this cost?
- How can water circulation affect my boiler and cause the 0b fault code to be displayed?
- What does my boiler engineer need to check on the pump?
- My boiler pump needs to be replaced, how much is this going to cost?
- Is there anything else that can affect water circulation?
- How can air locks be removed?
- How can heating sludge be removed?
What does the 0b fault code mean on my Viessmann boiler
If your Viessmann boiler is showing the 0b fault code, it’s due to the burner switching to lockout mode.
Your boiler will lockout when it thinks there is a problem that could either cause the appliance to be dangerous, or, cause damage to internal components. The printed circuit board (PCB) notices there’s a problem, locks out the boiler, and displays the 0b fault code.
What are the likely causes of the 0b fault code being displayed
Your repair company will need to check your Viessmann boiler to determine the exact fault. They’ll check the:
- Burner for blockages
- Water circulation
Can the 0b fault code be fixed on a DIY basis
Fixing the 0b fault code on Viessmann boilers is going to require the boiler to be taken apart. If you don’t have Gas Safe accreditation, you shouldn’t be taking apart gas boilers. Instead, you’ll need to call a Gas Safe boiler repair company that has had experience fixing Viessmann boilers.
Would a reset help to fix the problem with my Viessmann boiler
You shouldn’t reset your boiler to try and fix the 0b fault code. The reset function should only be used after the problem has been fixed, it shouldn’t be used to try and fix your boiler.
A Gas Safe heating engineer will diagnose and fix the problem. Once they’re confident the problem has been fixed, they’ll reset your appliance and that will clear the 0b fault code from the display panel.
How does a burner get blocked, and how can this affect the boiler
Your burner needs to produce a steady flame to heat hot water. Any blockage, regardless of how small, is going to affect the burner’s ability to produce a flame, and therefore, heat.
In older boilers, it’s common for carbon build-up to affect the burner’s efficiency. In extreme cases, the build-up is enough to block the burner to a point where it can no longer operate.
However, it’s more likely that the jet in the burner is the cause of the blockage. The jet is what supplies the burner with a steady flow of gas, and they’re extremely small and fragile.
Unlike the burner, it doesn’t take much to block the jet. And once blocked, the jet isn’t going to be supplying the burner with the gas it needs.
Can a burner’s jet be unblocked, or will it need to be replaced
If a blocked jet is causing the 0b fault code to be displayed, it can be unblocked, rather than replaced. And, that’s going to keep repair bills to a minimum.
However, you’ll want to get your Gas Safe boiler repair company to inspect the overall condition of the burner, to ensure it’s not a faulty burner that’s causing the issue.
If my burner needs to be replaced, how much will this cost
A burner replacement in your Viessmann boiler is likely to cost around £275. And, although the job only takes a day, it’s unlikely to be fixed on the same day as the call out.
Burners are usually “order in” items from local plumbing merchants. Including delivery time for parts, expect your boiler to be up and running within 2-3 days.
How can water circulation affect my boiler and cause the 0b fault code to be displayed
If the burner and jet aren’t the culprits, the next thing your boiler engineer will need to focus on, is water circulation. This means checking the pump, as well as checking there are no blockages or air locks in the heating system.
Your PCB wants to recognise that there’s a steady flow of water at the right times. That indicates that the pump isn’t just operating but is operating correctly.
When there are blockages, air locks, or problems with the pump, circulation of water around your heating system is going to be hindered. Your PCB will notice this thanks to various water sensors, and it will then lockout your boiler until the problem has been fixed.
What does my boiler engineer need to check on the pump
Starting with the basics, your engineer will want to see that the pump is running. And if it is, they’ll want to make sure it’s not too hot. If it is, this is a sure sign that the pump is blocked and is failing to circulate water at all.
If they need to take apart the pump, it’s likely they’ll bleed air from the component using the specifically designed bleed screw. And, if there are signs of heating sludge, they’ll want to remove this manually. Either of these obstructions are going to cause the pump to lack in ability when it comes to water circulation.
They’ll also want to check the speed setting on the pump is correct for your heating system. If it’s too low, water won’t travel around your system fast enough, will lose too much temperature, and mean that your heating system is incredibly inefficient.
If none of these checks bring up any issues, your engineer will want to test the pump using a multi-meter. They’ll check wires, connections and the pump unit to determine if there are any signs of weak or no power.
My boiler pump needs to be replaced, how much is this going to cost
On some occasions, the source of the fault could be the pump, and the only fix is a replacement. If that’s the case with your Viessmann boiler, you should expect a replacement pump to cost in the region of £250 and take one working day to be fitted.
Is there anything else that can affect water circulation
Air locks and heating sludge are both things that are going to hinder the pump’s ability to circulate water around your heating system, as well as to taps and showers.
How can air locks be removed
Your heating engineer will have already removed air locks from the pump using the bleed screw. But, most air locks occur in radiators and towel rails. And, these can be removed by using a specifically designed radiator key.
They’ll use this on the bleed valve of the radiator, to remove any air.
Once all air has been removed, it’s likely that the pressure in the system will have dropped. So, before resetting your boiler to clear the 0b fault code, they’ll need to top up the system with water via the filling loop.
How can heating sludge be removed
The most common form of blockage in a modern central heating system, comes from heating sludge. This consists of small rust particles that break off radiators, towel rails and even copper pipe work. As they work their way around your heating system, they form dirty heating water.
But, some large pieces of rust can easily lodge themselves in radiators, valves, towel rails and even boiler parts like the heat exchanger and pump. This can cause a blockage, and therefore, a circulation fault.
Your heating engineer can run a hot flush, using specifically designed cleaning chemicals. This will get rid of most heating sludge in your heating system.
However, over time more sludge will appear, so you’ll want to put in place some preventative measures. The most common preventative measure used today, is a combination of central heating inhibitor, and a magnetic system filter installation.
The inhibitor will sit in your heating system breaking down sludge into manageable chunks. As the sludge passes through your magnetic system filter, the filter catches these pieces of sludge and removes them from circulation.
All that’s left to do then, is to ensure the filter is cleaned with every annual boiler service.
Other Viessmann boiler issues
For more boiler issues regarding the Viessmann Boiler then please visit the Ideal Boiler Problems And Cures page.