Updated: 9th May, 2025
Looking for a guide to which boilers you shouldn’t buy? Look no further.
Shopping for a new boiler can seem like an impossible task, especially when there are so many different types, brands and models available on the market.
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If you haven’t already, you might want to check out our guide to the Best Boilers of 2025 to see what our top picks are but in this guide, we’ll be taking a look at the ones you should be avoiding.
In order to keep things fair, we’ve considered the following factors when compiling our list of the worst boilers of 2025:
Which? Annual boiler survey results
The brand’s overall reputation based on customer reviews
Warranty offered
The boiler cost
Awards and accolades
Which? is a UK organisation dedicated to testing and reviewing products and services in order to help consumers make more informed decisions before buying.
Each year, they put over 3,600 products to the test through their test labs, user trials and (where applicable) taste tests.
The final aggregated score is based on the following:
Reliability score
Customer score
Engineer recommendation
Build quality
Availability of parts
Ease of fixing faults
Ease of servicing
Based on the 2025 Boiler Survey, there was a clear loser: Ferroli.
Ferroli is an Italian brand based in Burton-on-Trent and received an unimpressive score of two out of five from consumers and just a single star from engineers.
Additionally, the brand got a 3 out of 5 reliability score, suggesting you can’t count on them to deliver high quality heating for a long time.
Overall, Ferolli received an aggregated score of just 35%, which is significantly lower than the majority of other boiler brands.
The Ferroli HE 27C in particular received particularly bad reviews and customers weren’t thrilled with the other models including the HE 32C and the HE38C.
Combined, these boilers were the worst rated by Which? in 2021.
So why aren’t customers- or engineers- impressed with Ferroli? Let’s find out…
Trustpilot is a digital platform that hosts reviews from existing customers to help potential customers to shop with confidence and, like Which?, make better informed decisions before buying.
The more consumers use the platform to share their experiences with brands, the richer the insights TrustPilot can offer.
On Trustpilot, the number of stars a customer gives determines whether they think the product/service was excellent (5 stars), great (4 stars), average (3 stars), poor (2 stars) or bad (1 star).
Of all the reviews based on customer’s experiences with Ferroli, just 65% gave them 5 stars whilst 22% gave just 1 star, rating the company as ‘Bad’ (true as of Jan 2025).
As a reference of how poor this score, the following scores are from some of the top boiler brands:
Viessmann - 80% Excellent, 5% Bad.
Worcester Bosch - 80% Excellent, 3% Bad.
Ideal- 87% Excellent, 3% Bad.
Alpha- Excellent 87% 7% Bad.
This comparison shows just how poor the reviews of Ferroli are. In particular, many poor and bad reviews refer to the engineers, warranty service, product failures and low quality parts.
Let’s look at these in closer detail…
Depending on the model, most Ferroli boilers come with a standard warranty of 1-5 years which covers any repairs or replacements proved to be faulty by the manufacturer.
The warranty on these parts ends when the warranty on the appliance expires.
This standard warranty period is rather short in comparison to companies such as Worcester Bosch that has a warranty of 12 years when installed by a Worcester Bosch engineer and Viessmann which has a standard warranty of 5 years with the availability to go up to 12 years when installed by a Viessmann engineer.
From the reviews, many customers complain about how difficult it is to arrange repairs under the warranty and the unwillingness to help by the aftercare team.
With so many issues and failures caused by the low quality parts, it’s no surprise most Ferroli boilers come with a one year warranty.
From the reviews, it is evident that Ferroli boilers are prone to failures and even when working, make loud clunky banging noises.
Prices for Ferroli combi boilers (excluding installation costs) range from £475 and £595, making them a budget boiler brand.
However, with so many failures and low quality parts that need replacing frequently, a boiler from Ferroli will likely end up costing you significantly more in the long run and will typically need to be replaced a lot sooner than a more expensive, yet reliable brand, such as Worcester Bosch.
As far as we can tell, Ferroli hasn’t received any UK awards in the last five years, however, back in 2016, their BlueHelix Tech 25C (The European name for the Modena HE boiler) won a few awards for being Best Boiler and Best Purchase in Italy and Spain by consumer survey magazines AltroConsumo and Compra Maestra.
Ferroli boilers have been known to break down so often that central heating engineers come out multiple times in the first two years. Normally, heating engineers are rarely - if ever, needed to service reliable boilers.
Some Ferroli boiler breakdowns have been so bad that the entire system has needed repair work, with replacement parts being delivered late.
Replacement parts are not kept in stock. When customers have breakdowns, the company has to deliver that part between four and six weeks later - and remember, no other heating engineers are allowed to complete the work instead.
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Vokèra is a boiler brand based across the UK and Ireland that is part of the Riello Group.
In the Which? Boiler Survey 2021, Vokèra came in second-to-last with an overall brand score of 50%.
Of all the reviews based on customer’s experiences with Vokèra, just 69% gave them 5 stars whilst 9% gave just 1 star, rating the company as ‘Bad’ (true as of Jan 2025).
Although this isn’t quite as bad as Ferroli’s reviews, Vokèra certainly don’t come close to the top boiler brands which have a minimum of 80% Excellent views.
When looking at the reviews, it seems that most issues are down to the complicated thermostat operation, frequent breakdowns and poor customer service.
According to one customer, the Vokèra thermostat was very difficult to operate and even their ‘techy’ daughter struggled to operate it, despite watching an online tutorial on how to use it.
With so many customers complaining about frequent breakdowns, it seems Vokèra are unable to find enough engineers available to resolve these issues as despite paying large callout fees of £125, customers had repairs cancelled and were left without heating and hot water for up to a week.
Most Vokèra boilers come with a very low 12 month warranty as standard, however, some offer an individual warranty between 2-7 years.
It’s no surprise Vokèra offers such a low standard warranty when so many of their boilers have frequent breakdowns as after a year they can wash their hands of any repair and labour costs which then fall onto the customer to cover.
Much like Ferroli, Vokèra boilers are one of the cheapest options on the market and, as the saying goes, you get what you pay for.
Although the initial prices between £499 and £650 may seem like a great offer, you could actually end up paying significantly more in the long run due to the cost of repairs and replacing your boiler sooner due to the very low warranty period.
Back in 2018, Vokèra’s Evolve boiler was nominated in the Domestic Heating Product of the Year- Boilers/Water Heaters category at the H&V News awards, however they lost to Firebird’s Enviroblue Combi HE boiler.
Some Vokera boilers simply will not ignite at all and need to be fixed urgently.
The diverter valve on Vokera boilers sometimes malfunctions when it heats up, which is common with heating systems.
These boilers can often create a range of loud sounds that occur at low pressure.
In a condensing boiler or any boiler with a condensate trap pipe, the pipe can block itself at random, thanks to unwanted debris.
Most free boiler giveaways involve an old boiler with major reliability issues or even a boiler that has broken. New boilers with modern designs are not an exception to this rule, either.
At iHeat, we only sell and install the best boilers available on the UK market and offer 10 year warranties on all of our boilers as a sign of our confidence that these models will be long lasting and reliable.
If you’re looking to get a new boiler for your home, why not get a free fixed quote on a brand new A-rated efficient boiler plus installation today with iHeat?
Always know what you want to search for, and make sure you understand the right boiler terms before you commit to anything. A conventional boiler might not be the kind of boiler you actually want, for example.
Know the dimensions and qualities of the place you want to install your boiler. Some boilers are better when placed higher up since they can use gravity to feed heated water around your home.
A rating score does not give you much information, but it can break down a company's general level of competence and product craftsmanship quite well. Three stars is far, far more of a risk than five stars usually is.
Always, always get a warranty if you can, and ideally a guarantee.
If you are stuck or do not know what to look for, get professional advice. Even advice from a friend who happens to be a plumber can be incredibly valuable.
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