Common Viessmann Boiler Problems & Repair Advice

Common Viessmann Boiler Problems & Repair Advice

Viessmann Boiler Problems and repair advice

Providing heating and hot water to our homes every single day is a big job and it’s all left up to our faithful boilers. They don’t even ask for much attention, tucked out of the way in a cupboard or under a kitchen worktop.

That is until you get up for your warm morning shower and the hot water never arrives. Rather than stare blankly at the cold water running out of the tap, reminiscing about the hot water you had just yesterday, there are some common boiler problems that can be solved relatively quickly without even needing an engineer.

If you have a Viessmann boiler, this handy guide will take you through some of the most common problems their boilers experience. Taking you from identifying a fault right through to fixing it, or knowing that you’ll need an engineer. Should the need for engineer arise, and if in doubt always contact one, use our free service to get quotes from reliable engineers near you.

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Who are Viessmann?

Viessmann is a family-owned company, that was founded in 1917 and since then has grown to have over 12,000 employees all around the world. They’re committed to the highest standard of manufacturing which has seen then become one of the leading international manufacturers of systems for heating, industrial energy and cooling. You can find out even more about them on the Viessmann page.

Top 5 Viessmann Boiler Problems

  1. Frozen condensate pipe

    With new condensing boilers, the small amount of waste gas that boilers naturally produce and turn to water as it cools is drained outside by the condensate pipe. In the UK we’re usually experiencing cold conditions, which means that it’s common for the water to freeze and cause a blockage in the condensate pipe.

  2. Low boiler pressure

    When your boiler has low boiler pressure, it can lead to your central heating system failing to function properly. Checking the pressure of a boiler couldn’t be simpler, simply take a look at the built-in pressure gauge, if you see anything below 1 then you may have an issue. Get to know even more with our guide to low boiler pressure.

  3. Boiler leaking

    Even the smallest of leaks can be a serious boiler issue. A leak could happen for one of many reasons but it tends to indicate that an internal component has broken, normally a seal or valve. This can lead to corrosion, rust or cause electrical components within the boiler to short circuit. Don’t try to repair the fault yourself, instead contact a Gas Safe registered engineer as soon as possible.

  4. Hearing strange noises

    If your boiler is making strange rumbling noises then that suggests limescale or sludge has built-up on your boiler’s heat exchanger, something known as kettling. Having the build-up, can restrict the flow of water within the heat exchanger which then overheats the water, causing it to steam and boil.

  5. Radiators not heating up

    Your radiators not heating up can be caused by a number of things, but most commonly it’s as a result of sludge or air build-up in the system. If the bottom of your radiator is getting hot but not the top, you may need to bleed it. Unless you’d like an engineer to carry this out, you can bleed the radiators yourself which our guide to bleeding radiators can take you through.

Which Boiler Issues Need an Engineer?

If in doubt about any boiler issues, always contact a Gas Safe registered engineer, but there are some common faults you’ll be able to resolve yourself. Use our table below to recognise any faults you might be experiencing with your boiler.

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Problem Possible Cause Do you need an engineer?
No heat or hot water Can be caused by several things including broken diaphragms and airlocks, failure of motorised valves, issues with the thermostat or low water levels Yes
Leaking and dripping Most likely to be a broken internal component but it will depend where the water is leaking from Yes
Banging, whistling or gurgling noises Air in the system could be causing this, otherwise it could be that the water pressure is too low Yes
Pilot light goes out The thermocouple could be broken which is in turn stopping the gas supply Yes
Losing pressure Could be a water leak in the system, the pressure relief valve needs replacing or due to recently bleeding radiators Only if there’s a leak
Frozen condensate pipe This fault should be displayed on your boiler as an error code or warning notification Yes
Thermostat issues Thermostat could be turned off or not set to the correct settings (time etc.) Consider replacing
Kettling Limescale or sludge building up on the heat exchanger Yes
Radiators not getting hot Sludge or air building up in the system or an unequal distribution of heat Your radiators will need to be bled which doesn’t require an engineer but if you don’t feel like carrying out the task yourself
Boiler keeps switching itself off Could be low water pressure, a problem with the thermostat or a lack of water flow due to a closed valve, air or the pump not circulating the water in the system properly Yes

Error Codes

When there’s a fault with your Viessmann boiler, it will make you aware by displaying an error code on the display screen. If you’re not sure what it means, consult our list of Viessmann error codes.

Should You Replace Your Viessmann Boiler Instead?

When your boiler has been providing heating and hot water to your home for a fairly long period of time, you might be thinking about replacing it. Those of you that live in a detached home could be making potential savings of as much as £305* a year. Take a look at the table below to see how much you could be saving depending on your current boiler rating and property.

House Type G (<70%) F (70-74%) E (74-78%) D (78-82%)
Semi-Detached £200 £140 £120 £120
Detached £305 £210 £180 £180
Detached Bungalow £155 £105 £90 £90
Mid terrace house £175 £120 £105 £105
Mid terrace house £95 £65 £55 £55

Who Should You Choose to Replace a Viessmann Boiler?

If you’re convinced that a new boiler is for you, then you’ll need to to think about who will do the installation.

Any installation should be carried out by a Gas Safe registered engineer, that’s the simple part. The big decision you’ll have to make, comes down to a local engineer or a national company.

With national companies, you’ll not only be getting your boiler replaced but be offered extra services like ongoing boiler cover and big brand protection, always a plus.

Local engineers, can offer extremely competitive rates and you’re likely to get a personal service throughout the installation from the first phone call to the last.

When it comes to getting quotes, we recommend getting up to 3, rather than just 1, so that you know you’re getting the best deal for you.

Boiler Insurance and Ongoing Cover

If your Viessmann boiler warranty has expired, then boiler insurance is something you might want to consider. Keep an eye out for any insurance that offers an annual service and safety inspections. You can take out insurance with your energy supplier but you’re absolutely no obligation to do so.

Viessmann Boiler Warranty

The majority of Viessmann boilers come with a 5 warranty as standard that covers parts and labour. Use our guide to Viessmann warranties for more information.

Once the warranty has begun, an annual service of your Viessmann boiler by a Gas Safe engineer will need to be arranged to keep the warranty valid for the entire duration. In addition to keeping the warranty valid, a service will help to keep the boiler running safely and efficiently for as long as possible.

To find trusted engineers near you, use our service to receive free quotes for a new boiler installation.

*According to the latest figures from the Energy Saving Trust

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