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Last updated: 4th April, 2024


Best Regular (Heat-Only) Boilers in 2024

Best Regular (Heat-Only) Boilers in 2024

Key takeaways

  • Heat only boilers are ideal for larger properties, providing reliable hot water supply
  • Best heat only boilers offer quiet operation and energy efficiency
  • Selection should consider factors like property size, budget, and installation requirements

Here at iHeat we’re experts in anything boilers, and understand at times the central heating market can be a tad confusing with lot’s of industry terms and many home heating options available.

Heat only boilers, often called conventional or regular boilers, provide an efficient solution for larger properties in the UK.

These boilers work by heating water within a hot water storage cylinder, feeding it to central heating systems and taps when needed. By having a separate hot water storage system, they can simultaneously deliver hot water to multiple outlets without a significant drop in pressure.

As the demand for energy-efficient and reliable heating solutions grows, the market has seen the emergence of various heat only boilers with impressive features and performance levels.

These boilers offer benefits such as quiet operation and superior energy efficiency. Choosing the best heat only boiler for your needs should consider property size, budget, and boiler installation requirements.

What is a Heat Only / Conventional boiler?

If you’re not one hundred percent sure about what is classified as a ‘conventional’ boiler, then let us simplify the term.

A conventional boiler, sometimes known as a ‘regular’ or ‘heat only boiler’, provides the heat for a home's central heating system and hot water cylinder.

A conventional boiler is suited to servicing larger properties with multiple bathrooms/radiators or business premises with high water demand.

Heat-only boilers require sufficient installation space within a property, using two storage tanks (feed & expansion) and the hot water cylinder. 

Although a combi is generally considered more space-saving, a modern heat-only boiler is still compact and can supply more bathrooms with hot running water than a combi can.

However, if you think your property is more suited to a combi, check out our handy guide to the best combis of 2024 right here!

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Understanding Heat Only Boilers

Definition and Working Principle of Heat-Only Boilers

Heat-only boilers, also known as conventional or regular boilers, are central heating systems that provide heat and hot water by working in conjunction with a separate hot water cylinder and cold water storage tanks.

These types of boilers heat the water in the system and transfer it to the hot water cylinder to be stored for later use. When hot water is needed, it is drawn from the cylinder and supplied to taps and showerheads.

Types of Conventional Boilers: Gas, Oil and LPG

Conventional boilers can be powered by various fuel sources, including natural gas, oil, and LPG (liquefied petroleum gas). Gas boilers are the most common, offering a convenient and cost-effective choice for many homeowners.

Oil and LPG boilers can be an alternative if the property is not connected to the main gas network. Each fuel type has its pros and cons, but ultimately, the choice depends on factors such as location, property size, and personal preferences.

Comparing Heat Only, Combi and System Boilers

Heat only boilers differ from combi and system boilers in terms of operation and installation:

  • Heat Only Boilers require separate hot water cylinders and cold water tanks, supplying stored hot water when needed. They are well-suited for larger properties with multiple bathrooms.

  • Combi Boilers provide on-demand heating and hot water. They don't need a separate hot water cylinder or cold water tanks. These are ideal for smaller homes with limited space and lower hot water demands.

  • System Boilers have a built-in hot water cylinder but don't require separate cold water tanks. They offer a compact and efficient heating solution for medium to large homes with a higher demand for hot water.

Advantages of Heat Only Boilers

Heat only boilers offer several benefits, including:

  • High Hot Water Output: They can provide a considerable amount of hot water to multiple bathrooms or appliances simultaneously.

  • Compatibility: They are compatible with older central heating systems, making them an excellent choice for retrofitting or upgrading an existing system.

  • Flexibility: Conventional boilers can be powered by a variety of fuel sources, allowing homeowners to choose the most convenient and cost-effective option.

Disadvantages of Heat Only Boilers

Despite their advantages, heat-only boilers also have some drawbacks:

  • Space Requirements: Due to their need for separate hot water cylinders and cold water storage tanks, they take up more space compared to combi or system boilers.

  • Slower Hot Water Delivery: Hot water delivery can be slower since the water has to be heated and stored in a separate cylinder.

  • Limited Hot Water Supply: The hot water supply is limited by the capacity of the hot water cylinder, meaning it can run out if there is a high demand for hot water.

Best Heat Only Boilers in 2024

Worcester Bosch Greenstar Ri Heat Only

Energy Efficiency Rating

‘A’ Rated @ 92%

kW Output


Dimensions (mm) height x width x depth

600 x 390 x 270



This powerful Worcester Bosch conventional boiler is part of the manufacturer’s hugely popular and industry recognised Greenstar’ branch.

Being compact enough to be easily wall mounted or fit into a standard kitchen cupboard, the Ri can comfortably supply between 15-20 radiators.

The Worcester Bosch Greenstar Ri is also compatible with Worcester Greenskies solar panels for a reduction in energy usage and emissions, as well as ongoing costs for the homeowner.  

Worcester Bosch Greenstar 27 Ri cost (inc. installation) from -

£2,730 Get a quote

Alpha E-Tec NX 28kW - Value

Alpha E-Tec Regular Heat Only

Energy Efficiency Rating

‘A’ Rated @ 88%

kW Output

15, 20, 25

Dimensions (mm) height x width x depth

600 x 390 x 305



Alpha’s E-Tec regular has been designed with the same attention to detail as their bestselling E-tec combi range and features many of the same innovative hallmarks.

A robust stainless steel heat exchanger encased within a compact shell means the E-Tec regular is built for enduring service, eradicating any worries concerning performance or longevity.

Easy access dry change NTC’s, and a new backlit display ensures usability is an implemented priority.

Alpha E-Tec Regular cost (inc. installation, NORTH ONLY) from -

£2,095 (15kW)Get a quote

£2,145 (20kW)Get a quote

£2,245 (25kW)Get a quote

Viessmann Vitodens 100-W 30kw

Viessmann Vitodens 100-W Heat Only

Energy Efficiency Rating

‘A’ Rated @ 92%

kW Output


Dimensions (mm) height x width x depth

600 x 375 x 285



The Viessmann vitodens 100-W represents a premium conventional boiler, utilising cutting edge components such as a Lambda pro matriX-Plus burner for high efficiency and control.

An Inox-Radial stainless steel heat exchanger only enhances the boiler's durability, while WiFi connectivity with Viessmann’s ViCare app enables premium temperature control and adjustment.

Viessmann Vitodens 100-W cost  (inc. installations) from -

£2,510 Get a quote

Worcester Bosch 8000 Life 30kW

Worcester Bosch Greenstar 8000 Life Heat Only

Energy Efficiency Rating

‘A’ Rated @ 92%

kW Output


Dimensions (mm) height x width x depth

780 x 440 x 365



Another one of Worcester Bosch’s elite Greenstar lineup, the 8000 Life is an extremely efficient heat-only boiler that can easily fit into a regular-sized kitchen cupboard while simultaneously serving a multi-bathroom property.

The 8000 Life is fully compatible with the Bosch EasyControl smart thermostat and boasts an improved display screen with simple button functionality.

Worcester Bosch Greenstar 8000 Life cost (inc.installation) from -

£2,895 Get a quote

Selecting the Best Heat Only Boiler

Considering Property Size and Hot Water Demand

When choosing the best heat only boiler for your home, it's essential to take into account the property size and hot water demand.

The efficiency of a boiler depends on both factors, so it's crucial to match your boiler size and capability with your home's requirements.

Bear in mind the number of inhabitants, hot water usage habits, and the presence of multiple bathrooms, as these aspects will impact your decision.

Tips for Sizing a Boiler

To adequately size a boiler, it's essential to assess the total heat output required to meet your home's hot water demands. Here are a few suggestions:

  • Consider the number of radiators in your home.

  • Calculate the total heat output needed for all the radiators combined.

  • Factor in additional hot water requirements, such as showers and baths, to ensure sufficient hot water capacity.

These calculations will help you select a boiler that is neither too powerful nor insufficient for your home's needs, ensuring efficient performance and avoiding unnecessary energy consumption.

Dealing with Multiple Bathrooms and Large Homes

Multiple bathrooms and large homes have different hot water needs compared to smaller properties. For instance, you may need more hot water storage or a higher heat output capacity. Flat or three-bedroom house residents may be less concerned about these issues.

It's crucial to opt for a boiler with enough capacity to cope with the demands of multiple bathrooms, radiators, and other hot water uses.

Higher output boilers are generally recommended for large homes with multiple bathrooms or increased hot water consumption.

Understanding ERP Efficiency

The European Union's Energy-related Products (ERP) Directive is a regulation for measuring and rating the efficiency of heating appliances, including boilers.

This information is useful when selecting a heat only boiler for your home, as a higher ERP efficiency rating indicates better energy utilization and potential savings on energy bills.

Ensure the boiler you choose has a good ERP efficiency rating, keeping in mind that a well-sized and efficient heat only boiler provides continuous and reliable hot water without wasting energy or causing significant wear and tear on components.

By considering property size, hot water demand, boiler sizing, and ERP efficiency, you'll be well-equipped to select the best heat only boiler for your home, ensuring efficient performance, energy savings, and the ideal comfort level for everyone under your roof.

Cost of Installation

The cost of installing a heat only boiler in a UK property can fluctuate depending on several factors, as outlined below:

  • Boiler model: Different manufacturers offer varying prices for their conventional boiler units. It's important to research and select a model within your budget while still maintaining quality and efficiency.

  • Labour: The process of installing a conventional boiler usually necessitates hiring certified professionals. Installation costs can vary depending on the labour charges in your area and the complexity of the project.

  • Additional materials: Alongside the boiler unit, other materials such as pipework, fittings, and controls may be required for the installation. These additional costs can influence the overall expenditure.

  • Location: The cost of installation may be impacted by the property's location, with prices potentially being higher in urban areas compared to rural regions.

While the cost of installing a heat only boiler may seem significant at first, it is crucial to consider the long-term efficiency and lifecycle of the system.

Many modern conventional boilers are built to last for years and can provide effective heating solutions for larger properties with higher hot water needs.

Frequently Asked Questions

What are the top heat only boilers in the UK?

There are several popular heat only boilers available in the UK market. Notably, the Viessmann Vitodens 100-W is an excellent choice, offering a range of sizes and high efficiency. Other reputable heat only boiler models include products from manufacturers such as Worcester Bosch, Vaillant, and Ideal. It is important to research well to find the best fit for your property.

Which heat only boilers have the best efficiency?

Efficiency ratings of heat only boilers vary and can be influenced by factors like age, model, and brand. Newer models typically have higher efficiency ratings, with leading brands like Viessmann, Worcester Bosch, and Vaillant usually offering products with excellent efficiency levels. Don't forget, though, efficiency is not the sole parameter to consider; performance also plays a crucial role.

Are there new conventional boilers available in the market?

Yes, new conventional boilers are continuously entering the market as manufacturers innovate their product lines. Keep an eye on well-established boiler brands like Viessmann, Worcester Bosch, and Ideal, to name a few, as they frequently introduce new models and improvements to their existing offerings.

How do popular conventional boilers compare in terms of cost?

Conventional boiler prices vary greatly – from around £480 for a small, entry-level model to £1,600 for a premium unit. Your choice will depend on factors like size, budget, and property requirements. It's wise to obtain multiple quotes from reputable suppliers and installers to ensure you find a cost-effective solution tailored to your specific needs.

What are the most reliable conventional boiler brands?

Reliability is an essential aspect when selecting a conventional boiler. Among the top brands with a reputation for producing reliable boilers are Viessmann, Worcester Bosch, Vaillant, and Ideal. Keep in mind, though, that proper maintenance and servicing can also impact the longevity and performance of any boiler, regardless of how reputable the brand.

Which heat only boilers are recommended by experts?

Experts tend to recommend heat only boilers from renowned brands like Viessmann, Worcester Bosch, and Vaillant. However, their recommendations often vary depending on factors like property size, location, and budget. It is always wise to consult with heating professionals to discuss your individual requirements, and ensure you get the best possible conventional boiler for your home.

Are heat only boilers good?

Heat only boilers, also known as traditional, regular, or conventional boilers, are a suitable choice for many homes. They work with a hot water cylinder and are particularly effective for properties with multiple bathrooms, where hot water demand is higher. Heat only boilers are compatible with older radiators and pipework, making them an ideal option for retrofitting in older properties.

Is a system boiler better than a heat only boiler?

The choice between a system boiler and a heat only boiler depends on the specific requirements of your property and household. System boilers combine the boiler and hot water cylinder into a single unit, making them great for homes with limited space. They also provide a constant supply of hot water and tend to be more energy-efficient. However, if you have an older property with an open vented system or multiple bathrooms, a heat only boiler may be a more suitable option.

How much does it cost to fit a heat only boiler?

The cost of fitting a heat only boiler varies depending on the model and the complexity of the installation. Generally, prices range from £500 to £2,000 for the boiler itself, plus additional costs for installation, which can vary between £500 and £1,500. Factors affecting the cost of installation include the location of the boiler, the need for new pipework, and any required modifications to the existing heating system.

How many radiators can a heat only boiler run?

The number of radiators a heat only boiler can run depends on its size and output capacity. As a rough guide, small boilers with an output of up to 18 kW can typically run 1-10 radiators, while larger boilers with outputs between 18 kW and 30 kW can handle around 10-20 radiators. However, it is essential to consult a heating expert to determine the ideal boiler size for your property and the number of radiators it has.

Which heat only boilers have the highest customer satisfaction?

Customer satisfaction with heat only boilers often depends on factors such as reliability, energy efficiency, and ease of installation. Popular and reputable brands that consistently receive positive customer reviews include Viessmann, Worcester Bosch, and Baxi. It is important to research each brand and their specific models to determine which heat only boiler best meets your needs.

How long do heat only boilers last?

Heat only boilers, also known as conventional, regular or traditional boilers, are known for their durability and longevity. On average, these boilers can last between 10 to 15 years, if well-maintained. However, the exact lifespan depends on various factors, such as the brand, model, usage, and maintenance history.

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