When searching for a new boiler, most people focus on finding the best options. However, it’s equally important to know which brands to avoid. This guide provides a detailed look at the worst-rated boiler brands of 2024, based on factors such as reliability, efficiency, warranty, and customer satisfaction. If you’re on the market for a new boiler and want to avoid potential headaches, read on to discover which brands have failed to meet expectations.
Criteria for Identifying the Worst Boilers
To determine the worst boiler brands, we evaluated several key factors:
- Which? Annual Boiler Survey Results
- Warranty Period
- Customer Reviews
- TrustPilot Ratings
- Awards and Accolades
- Customer Service Performance
- Price Range
- Efficiency Ratings
Each of these elements helps paint a comprehensive picture of the overall performance and reliability of various boiler brands. Here’s how each factor was weighted.
Worst Boilers by Survey Results
One of the most reliable sources for identifying poor boiler performance is the Which? Annual Boiler Survey. This survey combines feedback from over 12,000 boiler owners and 166 heating engineers, making it one of the most comprehensive resources for boiler ratings.
The survey evaluates:
- Reliability
- Customer Satisfaction
- Engineer Recommendations
- Build Quality
- Availability of Parts
- Ease of Repair and Servicing
The results show a clear picture: Ferroli emerged as the worst brand, with a dismal overall score of 35%, well below the industry average. This low rating was driven by poor customer satisfaction and engineer reviews. In particular, Ferroli’s HE 27C, HE 32C, and HE 38C combi boilers consistently ranked at the bottom of the list.
Ferroli Boiler Ratings
- Reliability: 3/5
- Engineer Score: 1/5
- Consumer Score: 2/5
Worst Boilers for Efficiency
Boiler efficiency is a critical factor for both the environment and your wallet. Since the introduction of Boiler Plus legislation in 2018, all new boilers must have an efficiency rating of at least 92%. However, some boilers barely meet this minimum requirement, resulting in higher energy costs over time.
While most modern boilers now fall within an acceptable range for efficiency, older models from brands like Ferroli and Vokera are notorious for poor energy performance. Inefficient boilers waste energy and money, making them costly to run.

Boilers with the Worst Warranty Terms
A boiler’s warranty is a crucial aspect of its overall value. The length and terms of a warranty can indicate the manufacturer’s confidence in its product. In general, longer warranties reflect better reliability.
Unfortunately, many of the worst-rated boiler brands, like Ferroli and Vokera, offer short and restrictive warranties, sometimes lasting only one or two years. In contrast, leading brands like Worcester Bosch offer warranties that extend up to 10 years, providing much greater peace of mind.
What’s the Difference Between a Warranty and a Guarantee?
While many brands offer warranties, Worcester Bosch goes one step further with a guarantee. A guarantee means the manufacturer promises to repair or replace the boiler within a specified period, regardless of the cause of failure. Warranties, on the other hand, often include conditions and exclusions, meaning you may end up paying for repairs even during the warranty period.
Worst Boilers by Price
While price is always a consideration when purchasing a new boiler, opting for the cheapest model can often result in poor long-term value. Cheap boilers are often less reliable, less efficient, and come with shorter warranties. As the saying goes, “buy cheap, buy twice.”
Here are some of the worst-rated budget boilers:
- Ferroli Sky Eco: £550
- Vokera Compact 25: £600
- Heatline Capriz 24: £500
These models may seem attractive due to their low upfront costs, but their poor efficiency, reliability, and limited warranty terms make them expensive in the long run. Conversely, more expensive models from brands like Worcester Bosch and Viessmann tend to offer superior performance and longevity.

Brands with the Worst Customer Service
Even the best boiler can run into issues, and when that happens, you want a manufacturer that stands behind their product with excellent customer service. Unfortunately, many of the worst-rated boiler brands fall short in this area.
Both Ferroli and Vokera are frequently criticized for poor customer service. Common complaints include long wait times for repairs, unhelpful customer support staff, and difficulty in sourcing replacement parts. On the other hand, top-rated brands like Worcester Bosch and Vaillant consistently receive high marks for their customer service, making them a safer choice.
Conclusion: Key Takeaways
If you’re shopping for a new boiler, it’s essential to consider more than just the initial purchase price. The worst-rated boiler brands, like Ferroli and Vokera, may offer lower upfront costs but often come with hidden expenses such as higher energy bills, frequent breakdowns, and poor customer support.
Key Points to Remember:
- Avoid Ferroli and Vokera: These brands consistently receive poor ratings for reliability, efficiency, and customer service.
- Don’t Sacrifice on Warranty: A short warranty is often a sign of low quality. Look for brands that offer warranties of at least 5–10 years.
- Price Isn’t Everything: While it may be tempting to buy a cheap boiler, the long-term costs of repairs and inefficiency can outweigh the initial savings.
- Check Reviews and Ratings: Use resources like the Which? Annual Boiler Survey and TrustPilot to make an informed decision.
- Customer Service Matters: In the event of a breakdown, you want a brand with a reputation for fast and effective service.
For those looking to invest in a reliable and efficient boiler, brands like Worcester Bosch and Vaillant come highly recommended. These brands not only offer superior performance but also come with extensive warranties and excellent customer service.
Before making a final decision, make sure to consider all factors, including warranty terms, efficiency, and customer reviews. By avoiding the worst-rated brands, you can ensure that your new boiler will provide reliable and efficient heating for years to come.

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This optimized article delivers the essential information without unnecessary fluff while applying key terms and staying focused on facts that matter to consumers.