Sime boilers review

Should you buy a Sime boiler or will you spend a fortune on engineer callouts and repairs?

Our survey shows Sime owners are highly satisfied, with owners awarding the brand an 82% customer satisfaction score – a full five-star rating. 

But this is only 20% of our total score. Which? members get full access to key insights and ratings from boiler engineers, plus the results from our reliability survey – which all determine whether Sime can be awarded the accolade of a Best Buy boiler brand.

Sign up to Which? to find out the complete picture about Sime and eight other gas boiler brands.

Sime engineers' review

We heard from 198 expert engineers who scored boiler brands on several tests. We asked them to score gas boiler brands on the following:

• The ease of sourcing spare parts 
• How easy it so to change a common component (a heat exchanger)
• The ease of servicing the brand's boilers
• The build quality of the brand's boilers
• The quality of technical support provided by the manufacturer
• Whether or not engineers would recommend the brand to consumers (we filter out incentivised and brand affiliated engineers).

We aggregate all of these scores and use them to create our 'overall engineers' score' which is 40% of our total brand score.

Which? members can see how engineers rated Sime gas boilers on all of these tests by logging in, while others can sign-up to Which? to unlock our full analysis.

Sime boiler reliability

We've asked people who bought a boiler in the past six years about whether it's fault-free. When faults are reported, we measure how serious the fault was, how long it took for the first fault to happen, and we make sure it was fixed by an engineer.

Using this data, Which? members can see which brands produce boilers that are less prone to fault than others.

Boilers are major purchases you should only make once every 10 to 20 years. You can keep yours for longer if you get it regularly serviced and get faults fixed quickly. 

See our guide to boiler servicing for more details.

Where to buy Sime boilers

It's easy to rush into making a decision, especially if your boiler breaks down in winter, but we recommend getting a couple of quotes from a qualified heating engineer and comparing costs. Our Trusted Trader service can link you up with vetted boiler installers in your area.  

You could also buy a boiler yourself and hire an installer, though make sure you seek expert advice before doing so, to have your current heating system assessed and identify the type of boiler that meets your specific needs. If you buy a boiler without having an installer lined up, you could find yourself struggling to find someone willing to set it up for you. An installer may have access to trade or wholesale prices, and will be able to recommend a model based on a holistic assessment of your home and heating system.

Only a Gas Safe Registered engineer/installer can install a new boiler: it's both dangerous and illegal to do so yourself if you're not qualified.  

Where to buy a boiler – find out what your options are

Are Sime boilers efficient?

New boilers must be A-rated, but how efficiently your boiler works in practice depends on several factors, including how you use it and how well it's installed. Use a Which? Trusted Trader for your boiler installation and regular maintenance.