Mistakes that can invalidate your boiler warranty Re February 10, 2022

Mistakes that can invalidate your boiler warranty

Customer and engineer in the kitchen next to boiler

Do I need a boiler warranty?  

You might’ve heard horror stories of boiler manufacturers not honouring their warranty for one reason or another. While this is not usually the case, it’s important to understand the mistakes that invalidate your boiler warranty and leave you out in the cold.

Boiler warranties are offered by the manufacturers when you buy a new boiler and can be extended for an additional cost. This warranty typically covers the repair costs, should the boiler break down during a certain period of time. This can provide peace of mind for at least a couple of years. Failing to stick to your boiler’s warranty terms and conditions could be an expensive mistake – so it’s important to fully understand it and avoid a heavy toll on your wallet or purse!

What’s a boiler warranty?

boiler warranty is the promise to repair your boiler for a certain amount of time after installation. Warranties are available in many different lengths. As standard, your new boiler will have a manufacturer’s warranty of at least 2 years (dependent on the manufacturer). Extended warranties can also be purchased for an additional cost.

Most boiler manufacturers run their own installer schemes, which are a recognition/accreditation for heating engineers who install a specific manufacturer’s boiler to a high standard. As an accredited engineer, an installer may be able to offer an extended warranty as the manufacturer knows your new boiler will have been installed by highly trained professionals, to specific standards.

What’s the difference between a warranty and a guarantee?

A boiler guarantee is nearly identical to a boiler warranty. Your new product will always come with one as standard, varies in length, and can be extended for an additional cost.

So, what’s the difference? The only difference between the two is that a boiler manufacturer’s guarantee is a promise to repair your boiler for a certain amount of time after installation, no matter what the cause is. There’s no small print that can catch you out if certain things may have caused the boiler to break down, and the manufacturer will send an engineer to your home and repair it regardless.

Worcester Bosch is one of the few manufacturers to offer a guarantee rather than a warranty. This is a major selling point and could often be the deciding factor in choosing your new boiler. Wouldn’t you opt for a guarantee, rather than a warranty for a similar price, especially given the reputation Worcester Bosch enjoy as the premium boiler brand available?

Boiler Brand

Guarantee/ WarrantyTerm
Worcester BoschGuarantee5-10 years
ViessmannWarranty5-10 years
VaillantWarranty5-10 years
IdealWarranty5-10 years
BAXIWarranty3-10 years


What should I look for in a boiler warranty?

While this is a hotly-debated topic, finding the right boiler warranty is as important as finding the right boiler. This is why it’s important to compare features before committing to a new boiler. Factors to consider should be;

  • The length of the boiler warranty 
  • If parts and labour are included
  • The parts which are covered by the warranty
  • If there are options to extend the boiler warranty
  • How the warranty could stay valid – almost all warranties will be invalidated by the below, but do read the terms and conditions to see if there aren’t any extra factors.

What could invalidate a boiler warranty?

1. Not getting the boiler installed by a Gas Safe engineer

When shopping for a new boiler, you’ll come across a handful of manufacturers that offer a longer warranty if the boiler was installed by one of their accredited installers. However, going direct to the manufacturer means you’ll miss out on the chance to compare and contrast for the best price.

In order to follow building and safety regulations, a new boiler must be installed by a Gas Safe Engineer. A Gas Safe Registered heating engineer is certified to work safely and legally on your boiler, ensuring you get the best possible install.

All of our engineers at WarmZilla are Gas Safe Registered and pass an intensive vetting process to make sure they’re up to the job. We also include with each boiler a system filter to clean out any impurities that may have got into your central heating system. For a boiler quote in 90 seconds, click here!

As a rough guide, these are the kind of prices you can expect to pay for different boiler installation types from WarmZilla, inclusive of VAT:

  • Combi to combi boiler swap – £1,489
  • System/Standard boiler to combi conversion – £2,249
  • Back boiler to combi conversion – £2,499
  • System to system – £1,995 (incl. free Hive Smart Thermostat)
  • Standard to standard – £1,649 (incl. free Hive Smart Thermostat)

2. Failing to register the warranty in time

Failing to register the boiler warranty with the manufacturer within 30 days of the installation is one of the most common traps that people fall for. This is because customers think it happens automatically (which clearly isn’t the case)!

That’s why when you buy a boiler from WarmZilla, we’ll register your guarantee or warranty with the boiler manufacturer on your behalf, for free. That’s another thing you don’t have to worry about when buying a new boiler with us!

3. Skipping an annual boiler service

There’s a misconception that if your boiler is brand new you don’t need to book an annual service, this is not only untrue but if you fall into the trap of not getting your boiler serviced by a gas safe engineer, you could end up with a massive bill for fixing faults that you thought would’ve been covered under warranty.

If you haven’t been on top of booking your boiler in for regular services, the manufacturer sees it as if you haven’t taken the appropriate steps to reduce the risk which can invalidate your warranty/ guarantee.

Think of an annual boiler service in the same way that a car has to pass an MOT to keep it roadworthy. Boiler service is a safety check to make sure it’s all working properly and by getting it checked regularly you can catch small issues before they turn into major issues. While a service might not fix your issues, they could prevent them from happening in the first place. This could save you money on costly repairs or even replacement but it also gives you peace of mind that your boiler is safe.

To give you an idea, the main things that are carried out on a boiler service are:

  • Visual inspection
  • Checking for corrosion and leaks
  • Ensuring boiler seals are in good condition
  • Checking gas/oil pressure
  • Testing the appliance to ensure the rate that the gas/oil is being burned is safe
  • Combustion analysis
  • Ensuring correct operation of components and controls by the customer

A service certificate is then issued detailing what has been done and any remedial works (if applicable).

Servicing your boiler can also save you money as it could be operating inefficiently – it might only need a few tweaks here and there to correct it and put it back to how it should be, saving you money on utility bills. 

The cost of annual boiler servicing will vary, depending on who carries it out and what kind of boiler you have – but on average the cost will be between £75 – £150 for a local heating company.

Boiler warranty myths

When it comes to keeping our homes warm in winter, it seems everyone’s got an opinion. There are plenty of misconceptions out there when it comes to heating systems and boiler warranties in particular. 

One of the most common boiler warranty myths is that your boiler is covered under your home insurance so you don’t have to worry about getting a boiler warranty or boiler cover plan.

This is untrue because home insurers simply don’t usually include the boiler within the policy. Although you might be able to add the boiler to a separate policy (in some cases) or have it covered by your home emergency cover on some occasions, we advise reading your home insurance policy terms carefully before making any assumptions that can lead to having to fork out a huge sum on boiler repairs.

Who do I call to claim on my warranty?

In the unlikely event that your boiler needs some extra TLC during the warranty period, the best thing to do is to call the boiler manufacturer directly. Here, we’ve collated some of the manufacturers’ boiler warranty lines so you can give them a ring if you need to.

  • Worcester Bosch 0330 123 9339
  • Viessmann 01952 675000
  • Vaillant 0330 100 3150
  • Ideal boilers 01482 498660
  • BAXI 0330 678 0917

Boiler brands such as Worcester Bosch, Vaillant and Ideal are well known for their superb aftercare services, so be sure to read up on the best boiler brand aftercare.

Is my smart thermostat covered?

Smart thermostats are rapidly becoming a popular trend for those of us who like to keep our home up-to-date with the latest gadgets, but they can also be a nifty way to save yourself some cash on your heating bills!

The question we get asked a lot here at WarmZilla is “Is my smart thermostat covered under my boiler warranty?”. To answer this, only manufacturers’ own thermostats such as the Bosch EasyControl will be covered by the manufacturer warranty, and only if they were installed and registered at the same time as the boiler.

On the other hand, smart thermostats such as Google nestHive Active Heating and Neomitis Wireless Digital Room thermostats will have their own warranties, so you’ll need to reach out to them directly.

Takeaways - key points to remember for your warranty/guarantee:

  • Ensure that your boiler has been registered with the manufacturer. This can either be done by the installer or yourself.
  • Complete the Benchmark form and keep it with your boiler manual.
  • Make sure your new boiler is registered with the manufacturer within 30 days of installation, many installers will do this – but make sure you check.
  • Check what the warranty/guarantee covers – Repairs, replacement parts etc.
  • You must have your boiler serviced by a GasSafe registered engineer on an annual basis.
  • Enquire about an extended warranty if available.


It is the promise to repair your boiler for a certain amount of time after installation.

A boiler guarantee is almost identical to a boiler warranty. There is only one difference between the two, and that is that a boiler manufacturer’s guarantee is a promise to repair your boiler for a certain amount of time after installation, no matter what the cause.

You must keep the following in mind when looking at a boiler warranty; the length of the warranty, if parts and labour are included, which parts are covered by the warranty, the possibility of extending a warranty and the warranty’s T&Cs to stay valid.

The three major things that could invalidate a boiler warranty are; not getting the boiler installed by a Gas Safe engineer, failing to register the warranty in time and skipping an annual service.

To claim on your boiler warranty, we advise you to call the boiler manufacturer directly.