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Last updated: 10th May, 2024


Glow Worm Boiler Reviews

Glow Worm Boiler Reviews

Key takeaways

  • Glow Worm boilers have a reputation for being cost-effective and reliable.
  • User satisfaction and expert reviews in 2024 point towards improved performance in recent models.
  • After-sales service and maintenance are important factors influencing consumer decisions.

In 2024, Glow Worm continues to offer a broad range of boilers, each tailored to different needs.

Glow Worm boilers have gained attention for their balance of performance and value, becoming a point of consideration for homeowners in 2024. With customer satisfaction playing a core role in a buyer's guide, the latest range of Glow Worm boilers has been discussed frequently in terms of efficiency, cost-saving, and reliability. 

Consumer reviews and boiler experts have weighed in, providing a spectrum of views that help in painting a comprehensive picture of what Glow Worm offers in its 2024 suite of heaters.

While not traditionally seen as a premium brand, Glow Worm's recent models have shown a positive trend in user experience and performance metrics which align closely with more expensive options. The diversity in boiler types, paired with advanced features and technologies, cater to various household needs. 

Considerations for prospective buyers include installation specifics, after-sales service, and the practicalities of boiler maintenance. While the pricing is competitive, it's the long-term efficiency and performance that often clinch the decision for consumers exploring the market for a reliable boiler.

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Overview of Glow Worm Boilers:

Glow Worm maintains a significant presence in the UK boiler market, renowned for manufacturing affordable and efficient boilers. This Derbyshire-based boiler manufacturer is a subsidiary of the Vaillant Group, known for high-quality heating products.

Product Range: Glow Worm offers a diverse range of heating systems, focusing on three primary types:

The combi boilers blend hot water and central heating capabilities into a single unit, negating the need for additional hot water storage. Their combi range is designed to suit various domestic requirements, offering impressive efficiency levels and compact designs.

Regular boilers, often found in traditional setups, work with a separate cylinder and are suitable for homes where multiple hot water outlets are used simultaneously.

System boilers differ, with major components like the pump and expansion vessel built in, simplifying installation and maintenance tasks.

Latest Innovations: Glow Worm's 2024 range includes models with the latest technology that conforms to UK's stringent energy standards. Customers appreciate the intuitive controls that make day-to-day operation of the boilers straightforward.

Reputation: Their reputation for reliability is solidified by strong reviews and the backing of experienced engineers. Positive feedback highlights satisfactory customer experience and professional after-sales support.

Conclusion: Glow Worm boilers continue to be a competitive option, offering a balance between performance and price, suitable for varied UK households.

Types of Glow Worm Boilers 2024: an in-depth look-

In 2024, Glow Worm continues to offer a broad range of boilers, each tailored to different needs. They cater to various household sizes and priorities, prioritising energy efficiency and reliability.

Available Vaillant Combi Boilers 2024

The combi boiler is prized for its compact, all-in-one design. This year, Glow Worm's combi boilers are highlighted as follows:

  • Budget Model: Aimed at cost-conscious consumers, these boilers blend functionality with an attractive price point.

  • Premium Model: These provide advanced features, including higher efficiency and more precise control over heating and hot water.

Available Vaillant System Boilers 2024

System boilers, which require a separate cylinder, are well-suited to homes with higher hot water needs. Key offerings include:

  • Varying Capacities: From models catering to smaller homes to those designed for large properties.

  • Energy Efficiency: All system boilers now come with a high ErP rating, reducing consumption and costs.

Available Vaillant Regular (Heat-Only) Boilers 2024

For homeowners with traditional heating systems, regular, or heat-only boilers are a suitable choice:

  • Multiple Sizes: Options range from small to large to fit the scale of the property and its radiators.

  • Efficiency: Even these traditional models are engineered to maximise energy efficiency where possible.

Key Features and Technology

In the 2024 range of Glow-worm boilers, several technological advancements come into play, focusing on enhancing efficiency and user experience by incorporating sophisticated controls and robust heat exchangers.

Energy Efficiency

The latest Glow-worm boilers are designed to operate exceptionally efficiently, adhering to the high standards of the 'ErP' (Energy-related Products Directive). These boilers are marked by their ability to convert fuel to heat in the most effective manner, which often results in significant energy savings for the homeowner. Central to their operation is a Grundfos pump, a vital component renowned for its durability and efficiency.

  • Grundfos Pump: Ensures optimal energy consumption by adapting to the boiler's varying heating demands.

Heat Exchanger Design

The heat exchanger within Glow-worm boilers plays a pivotal role, as it is the primary component responsible for transferring heat from the combustion process to the water circulating in the system. Glow-worm's heat exchangers are engineered with a focus on maximising this transfer, and they do so with less susceptibility to wear and corrosion.

  • Materials: Utilise long-lasting and corrosion-resistant materials.

  • Structure: Engineered to provide a large surface area for maximum heat transfer.

Controls and Accessories

Advancements in Glow-worm's boiler controls have made it easier for users to manage their heating systems for optimal comfort and efficiency. Among these controls, the incorporation of wireless thermostats stands out. Additionally, users have access to a range of accessories that cater to their heating system's specific needs.

  • Wireless Thermostat: Allows homeowners to adjust and program their heating from anywhere.

  • Accessories: User-friendly and designed to enhance the functionality and performance of the heating system.

Installation and Fitting

When considering a new Glow Worm boiler, the installation and fitting are essential to ensure optimal performance. The process requires professional expertise, and costs can vary based on several factors.

Installation Process

Choosing the right model is just the start; the installation process of a Glow Worm Boiler must be carried out by a certified heating engineer to ensure safety and compliance with UK regulations. Initially, the heating engineer will assess the property to determine the appropriate boiler type and position. They may suggest a combi boiler for smaller homes or a system boiler for larger properties with higher hot water demand. Once the boiler type is established, the engineer prepares the area, which involves removing the old boiler if necessary and preparing the connections for water, gas, and electricity.

Installation Cost

Cost is a key consideration, with installation costs influenced by the complexity of the job. A straightforward combi boiler swap may cost around £1,595, whilst converting from a system boiler to a combi boiler is usually more involved, thus increasing the price to about £2,390. If homeowners require an entirely new fitting, with no previous boiler in place, this can rise to £2,795. Keep in mind that additional work, such as replacing pipework or radiators, can add to the overall cost.

Boiler Swap/Conversion

Average Price Range

Combi to Combi


System to Combi


New Installation


Back Boiler to Combi


System to System


Megaflo Unvented Boiler


Choosing an Installer

The selection of an installer is a process that warrants care and attention. Homeowners are advised to engage installation companies with certified engineers, ensuring the installer is registered with the Gas Safe Register. It's worthwhile seeking multiple quotes to ensure competitive pricing. Not all boiler installers offer the same level of service, so it's vital to check reviews and verify the installer's credentials and warranty offerings on their work. Proper fitting is paramount; thus, homeowners should not compromise on the installer's experience for a slight reduction in cost.

Pricing and Value for Money

Glow Worm boilers are known for their competitive pricing and value for money. In 2024, their combi boiler prices range from £550 to £1,555. These costs vary based on the model's size, kW output, and flow rate. For those looking to upgrade from a combi boiler to a newer model, prices average around £1,595.

If a homeowner is considering a system boiler to combi conversion, they can expect to pay approximately £2,390. A new boiler installation typically costs about £2,795. Transitioning from a back boiler to a combi boiler is a more extensive job, and thus more costly, with prices hovering at about £3,199.

The system boiler replacement prices stick to the realm of affordability, costing roughly £1,895. Additionally, the Megaflo unvented boiler system is available for about £2,390, providing a more sophisticated option for those who need it.

Glow Worm's pricing strategy reflects a commitment to offering products that are affordable without compromising on quality. Whether consumers need a replacement for an ageing boiler or are making the switch to a more energy-efficient system, the pricing spectrum aims to accommodate a variety of household budgets. While Glow Worm is not always the least expensive on the market, their pricing often undercuts premium brands while offering reliable and efficient heating solutions.

Boiler Efficiency and Performance

When selecting a Glow Worm boiler, efficiency and performance are paramount considerations. These attributes directly influence energy consumption and operational costs.

Energy Efficiency Rating

Glow Worm boilers exhibit a commendable ErP A-rating for energy efficiency. This rating is symbolic of the boilers' adeptness at converting fuel to heat with minimal waste. Householders can anticipate a potential reduction in their energy bills, given that an A-rated boiler operates at a minimum of 90% efficiency.

Heating Output and Capacity

The Glow Worm range includes models with varied heating outputs, suitable for different home sizes. A notable model, the Glow-worm Ultimate₃ combi boiler, has a 30kW heating output, which makes it apt for average-sized UK homes, typically encompassing 3-4 bedrooms. The high output ensures that homes receive efficient heating and hot water supply, reflecting the capacity to meet domestic requirements effectively.

Customer Satisfaction and Reviews

In 2024, assessments of Glow-worm boilers reveal a pattern of strong customer satisfaction. A review of Trustpilot testimonials shows warmth towards the brand, with mentions of efficient new boilers and a marked downturn in utility bills. Customers articulate their support, promising to recommend Glow-worm to others, advocating for the product's reliability and cost-effectiveness.

Customer scores, on average, reflect a positive reception. Data suggests that roughly 90% of Glow-worm owners find themselves content, if not very much so. A customer score, strategically calculated, places satisfaction ratings high on the scale, though recommendation levels trail slightly behind.

A comparison on a platform such as Which? suggests Glow-worm's standing is on par with industry averages for recommendation likelihood. This indicates a consistent level of trust in the brand's range.

  • Price: Across various review platforms, the value for money stands out as a frequently highlighted point.

  • Energy Efficiency: Glow-worm’s boilers, especially models like the Ultimate₃, with an ErP A-rating, demonstrate a commitment to reducing energy consumption. This aspect is often underscored in customer feedback.

  • Reliability: Historical trends and recent reviews iterate the brand's focus on building dependable products.

In summary, Glow-worm seems to maintain a reputable position in the minds of consumers, which is supported through a variety of feedback channels that illuminate the brand's dedicated service and product quality.

Warranty and After-Sales Service

Glow-worm boilers come with the assurance of a sturdy warranty period. On purchasing a boiler from their 2024 range, consumers can benefit from a 7-year warranty, which promises the repair or replacement of faulty components within this timeframe. The company's commitment to their products is further reflected in the option for consumers to extend their warranty, provided they meet certain conditions set forth by Glow-worm.

The after-sales service offered by Glow-worm is structured to provide ongoing support through their dedicated customer service team. Should a boiler issue arise, customers can reach out to the company for assistance. Moreover, homeowners who wish to ensure the longevity and efficiency of their boilers can opt for Glow-worm's annual boiler service. This preventative measure is a proactive step towards maintaining boiler health.

For the professional installer, Glow-worm has established Club Energy – a specialist scheme aimed at supporting installers in providing excellent service to their customers. This membership grants access to benefits like extended warranties and dedicated technical support lines, allowing for a seamless after-sales service experience.

Here is a brief summary of key warranty and service features:

  • Warranty Length: 7 years standard, with the option for an extension

  • Annual Service: Suggested to maintain boiler performance and warranty validity

  • Club Energy: Benefits scheme for installers, enhancing their service capability

In summary, Glow-worm’s warranty and service propositions reflect a robust support system for homeowners and installers alike, with a focus on boiler efficacy and customer satisfaction.

Common Issues and Maintenance

Glow Worm boilers generally have a reputation for being reliable, but like any machine with moving parts, they may experience issues. Periodic maintenance is crucial to ensure the longevity and efficiency of these boilers.

Servicing: It is recommended that Glow Worm boilers receive service annually by a qualified technician. Regular servicing helps to maintain reliability and can prevent common problems from occurring.

No Heating or Hot Water: A frequent issue encountered by users is the absence of heating or hot water. This may be attributed to various factors such as valve failures, thermostat problems, or pressure discrepancies. Solutions often include checking for error codes, assessing thermostat settings, or re-pressurising the system.

Error Codes: When faults arise, Glow Worm boilers display specific error codes. Reference to the manual or a quick consultation with a servicing professional can decode these errors and inform the appropriate corrective action.

Common Faults

Possible Solutions

Loss of pressure

Check for leaks, re-pressurise boiler, replace pressure relief valve if needed.

Faulty thermostat

Replace or recalibrate the thermostat.

Ignition failures

Clean the ignition electrodes, replace if necessary.

A reset might be needed in the event of a lockout, which is simply performed by pressing the reset button for a few seconds. However, persistent need for resets indicates a deeper issue that requires expert attention.

In summary, while maintenance and addressing issues as they appear can be straightforward, it's essential to use the services of professionals who are adept at handling Glow Worm boilers. They can ensure your boiler operates efficiently, potentially cutting down on utility bills and providing peace of mind regarding safety and reliability.

Comparisons with Competing Brands

When assessing Glow Worm boilers, it is essential to consider how they stack up against market leaders like Vaillant and Worcester Bosch, particularly in terms of price and build quality.

Against Vaillant and Worcester Bosch

Glow Worm boilers, often regarded for their cost-effectiveness, find themselves in stiff competition with the likes of Vaillant and Worcester Bosch. Vaillant boilers are acknowledged for their efficiency and connectivity features, offering a range of smart controls that appeal to a modern audience. Worcester Bosch, an established name in the heating industry, is synonymous with reliability and customer satisfaction. Their commitment to after-sales support and service is noteworthy. Comparatively, Glow Worm boilers may not carry the same brand prestige, but they hold their own by offering a satisfactory blend of performance and affordability.

Price and Build Quality

The pricing strategy of Glow Worm targets a more budget-conscious segment of the market without compromising significantly on build quality.

  • Price Points (Approximations):

    • Glow Worm: The Ultimate 3 30kW system around £800 (boiler only).

    • Worcester Bosch: Comparable Greenstar 4000 combi boiler approximately £1,200.

Glow Worm’s competitive pricing undercuts the expense associated with Worcester Bosch systems, sometimes by considerable margins. Reflecting on build quality, while Glow Worm may not be as expensive as its counterparts, it manages a commendable level of build integrity and durability. However, it's important to note both Vaillant and Worcester Bosch have options that might be more expensive, but also tout additional features and, in some cases, longer warranty periods which align with their higher price points. Thus, consumers make their choices depending on both their budgetary constraints and their expectations for quality and additional benefits.

Installation Specifics for Different Boiler Models

Glow-worm boilers are known for their robust performance and versatile range. Each model has specific installation requirements that adapt to various home settings. The Ultimate 3 system is one model that stands out for its compact design, making it ideal for placement within a standard kitchen cupboard. This allows for a discreet and space-efficient installation, maintaining the aesthetic of the kitchen space.

Installation procedure varies depending on whether one is opting for a direct replacement boiler or system conversion. Alike boilers are swapped with relative ease. For instance, a combi boiler can be directly replaced with a new combi boiler from Glow-worm within the same day, minimising disruption.

Boiler Model

Installation Complexity

Special Considerations



Space for compact fit



Existing pipework adjustments



Space for hot water tank

Further, the system boilers, such as the Ultimate 3 System, are designed to be flexible in their installation. When converting from a system boiler to a combi, more extensive work may be necessary. Modifications could involve changing the pipework layout or removing any existing tanks.

Another key feature of Glow-worm boilers is their quiet operation. This facilitates installation in living areas without fear of disturbance. Installers often recommend these boilers for family homes because they balance efficiency with noise reduction effectively.

In conclusion, the precise installation details can be influenced by factors like the type of existing boiler, the desired model replacement, and the intended boiler location. It's essential to have a clear and well-planned installation strategy, and consulting with a certified heating technician will ensure that the chosen Glow-worm boiler is fitted to meet the household's heating needs with maximum efficiency.

iHeat New Boiler Costs

Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.

Effectively, new boiler cost can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer. 

Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.

Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type. Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat (guide only).

Installation Type

Price (inc VAT)

Combi to combi swap


Get a quote

System to combi conversion


Get a quote

New boiler install


Get a quote

Back boiler to a combi


Get a quote

System to system


Get a quote

Frequently Asked Questions

Are Glow-worm good boilers?

Glow-worm boilers are generally considered good, reliable heating solutions. With a high satisfaction rate among users, they offer a suitable option for residential heating needs. However, preferences and experiences may vary based on individual requirements and use cases.

Are Glow-worm and Vaillant boilers the same?

Although both brands are part of the Vaillant Group, Glow-worm and Vaillant boilers are not the same. Vaillant is typically positioned as the premium brand, while Glow-worm attracts those looking for budget-friendly yet efficient options.

How efficient is a Glow-worm boiler?

Glow-worm boilers often come with an ErP A-rating, indicating high levels of energy efficiency. They are designed to reduce energy consumption, benefiting the environment and the user's utility bills.

Is Glow-worm a budget boiler?

Yes, Glow-worm is considered to be in the budget category of boilers. It is positioned as an affordable choice, offering competitive installation costs without compromising on quality.

Are Glow-worm boilers noisy?

Glow-worm boilers are designed to operate quietly. The level of noise is usually within a comfortable range and shouldn't be a cause for concern for most users.

What is the most economical temperature for my Glow-worm boiler?

The most economical temperature for your Glow-worm boiler will depend on your specific model and household requirements. However, setting the thermostat to an optimal range, often around 18-21 degrees Celsius for living spaces, can ensure efficiency while maintaining comfort.

What is the number 1 boiler in the UK?

Identification of the number 1 boiler can be subjective, based on criteria such as reliability, efficiency, and customer satisfaction. Glow-worm boilers are highly regarded for their value for money, though they may not be classified as the top premium brand in the UK.

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Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.