How To Fix Common Viessmann Boiler Problems

how to fix comon viessmann boiler problems

Common Viessmann boiler problems & how to fix them

Viessmann is well known for the high quality of its heating systems. They even claim on their website that they produce the ‘UK’s most reliable boilers’.

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Viessmann recently celebrated one hundred years in business, and they have sales offices in eleven different countries.

So, while Viessmann boiler problems may not happen often, there will be times when a fault develops that needs attention after the boiler installation

In this article, we’ll take about which problems are most common. Then we’ll look at which issues you can fix yourself and which need a visit from a Gas Safe engineer.

Whether you have Viessmann Vitodens 200 problems or need help with Viessmann Vitodens 100 troubleshooting, we can help!

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What Are The Most Common Viessmann Boiler Problems?

Many of the common problems are quick and easy to identify. Radiators not warming up and having to take a cold shower are likely to be spotted pretty quickly!

Some problems, though, start small and get bigger over time, especially with cheap boilers. That tiny leak from the radiator will become a bigger issue if not quickly fixed. Fixing it is much better than paying what a new boiler cost.

Some of the most common boiler problems include:

  • Burner blockage

How To Fix A Leaking Viessmann Boiler

A leaking boiler is usually a sign of a serious problem. It can lead to other components rusting or the shorting of electrical components in the boiler. This is something that needs immediate attention.

Boiler Pressure Valve Fault

When the pressure valve is the source of the leak, first check if the boiler pressure is too high.

If the gauge on the boiler is in the red, then you can bleed the boiler to reduce it.

Sometimes this can be caused by sludge or an obstruction in the system. In that instance, you’ll need to call out a Gas Safe engineer.

Leaking Pipe Fittings

If the boiler leak is coming from pipe fittings, a ¼ turn of the fitment might do the trick. If that doesn’t work, then an engineer will need to check the PTFE tape inside of the Fitting.

Seals in The Boiler Pump

Over time, the rubber seals can become damaged, which is a common cause of leaks in older types of boilers. Often the level of corrosion means that it makes more sense to get a replacement boiler than attempt repairs.

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Q What kind of fuel does your boiler use?

Fixing Viessmann Boiler Problems Yourself

If you’re having problems with your Viessmann boiler, troubleshooting may mean that you can sort out simple issues yourself & stop you needing to pay the boiler replacement cost.

Our fault-finding tips help you to fix three common problems.

Frozen Condensate Pipe

The condensate pipe drains the small amount of wastewater produced by condensing boilers. In cold spells, the water freezes and blocks the pipe.

To sort out this one just pour hot water over the blocked area until the ice has melted.

Low Boiler Pressure

If your boiler has low boiler pressure, then your central heating system won’t work correctly.

1. Switch the boiler off at the mains

2. Now, wait for the system to cool down.

3. Locate the filling loop and if not already attached, secure it tightly.

4. Open the valves of the filling loop, and you’ll hear the water entering the boiler.

5. Once the pressure gauge reaches 1, turn off the valves and release the filling Loop.

Radiators not Heating Up

The most common reason for a radiator not heating up is trapped air.

1. To release the air, use a radiator key to open the bleed screw.

2. When you hear a hissing sound and water starts coming out, close the screw.

3. The radiators should now start to warm up.

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Which Viessmann Boiler Problems Require An Engineer

Some boiler problems, especially those related to a gas boiler, are strictly the territory of an engineer. These include:

Burner Blockage

The burner supplies the correct amount of fuel and air to generate heat. If it gets blocked, the boiler won’t function.

Pilot Light Goes Out

If the gas supply to the boiler is being interrupted, it might be caused by a broken thermocouple. This safety device turns off the gas supply when the pilot light goes out.

Once replaced, the seals on the system need to be checked to ensure the system is safe.

Viessmann Boiler Warranty – Which Problems Are Covered?

The length of the warranty will vary with the new boiler model chosen. However, while in force, it will cover your system against manufacturing and material defects.

Usually, both parts and labour are covered. Full details of the warranty available on each model can be found here.

Do be aware that problems associated with installation are not covered. There are several other exclusions so do check you’re covered before you request a Viessmann engineer.

How Do I Reset My Viessmann Boiler?

If there’s a fault code displayed or there’s a risk from operating your boiler, it will lockdown. Once repaired, you then need to reset your boiler for it to work again.

To reset the boiler, push the reset button for ten seconds. Then wait a few minutes for the boiler to light.

The location of the reset button varies between models. If it’s not obvious, check your manual or contact Viessmann Customer Service.

Do be aware that calls to the Viessmann technical team are routed to a call handling service out of hours. So we recommend getting in touch between 08.30 and 17.00.

Maintaining Your Viessmann Boiler

The Viessmann boiler service is the most important part of keeping a maintained system.

The engineer will ensure that your boiler is operating safely and check all parts for wear and tear. If you’re installing the best system boiler you want to ensure you look after it.

Maintenance tasks to keep your boiler working throughout the year include:

  • Keeping air grilles clean and unobstructed.
  • Keep the boiler pressure between 1.2 and 1.5 bars.
  • Bleed radiators to get rid of trapped air.

When To Replace Your Viessmann Boiler

Most boilers have a lifespan of 10-15 years. But if you have to call out an engineer on a regular basis, then it may be better to opt for a new boiler.

Other signs which suggest a replacement is needed are noisy boilers or radiators, and leaks. Even the best combi boiler has to give in one day.

Energy bills are higher for older, less efficient, boilers so a replacement may not cost too much more over its lifespan.


Regular boiler servicing is the best option to avoid problems. It also reduces the risk of a carbon monoxide leak or finding yourself without heat and hot water.

If the time has come to find a new boiler, our fixed price service means you get the boiler you need with the risk of unexpected costs. check out the fantastic Viessmann 050 combi now!

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