Best Heat-Only (Conventional) Boilers 2025

Conventional boilers can sometimes be the best fit for a household’s heating and hot water needs, especially if you have low mains water pressure or a large home. 

These traditional systems, also known as heat-only boilers or regular boilers, have been a reliable heating solution for decades, so let’s explore their unique advantages and why they might be the ideal choice for your home. We’ll also give you our recommendations for some of the best conventional models currently available and provide insights into new boiler costs.

Our top picks

• Vaillant ecoTEC plus
• Alpha E-TEC Regular
• Viessmann Vitodens 200-W Regular
• Worcester Bosch Greenstar 8000 Life Regular
• Glow-Worm Energy

Best Conventional Boiler Models

Here are our top choices from well-known boiler brands to help you make an informed decision.

Vaillant ecoTEC plus Regular

The Vaillant ecoTEC plus open vent boiler comes in six different power outputs from 12 to 35kW, making it suitable for a wide range of homes. Small enough to fit into a kitchen cupboard, this powerhouse has achieved an ErP A rating for efficiency.

The ecoTEC plus can cleverly work out when you don’t need as much heating power. It then drops down to using just 16% of its power, providing significant savings on fuel costs and reduced carbon footprint.

Outputs (kW)	Warranty	Efficiency	Price Range
12, 15, 18, 24, 30, and 35	5-year standard guarantee, extendable up to 10 years when registered by a Valliant Advance installer	A-rated, with up to 89.2% efficiency rating	£800 to £1,500

Features

• Multi-Sensor System for optimal performance
• Compact design fits in a kitchen cupboard
• ErP A rating for efficiency
• Quiet Mark approved for low noise operation
• Flame Lift Detection for added safety
• High-quality automotive-grade aluminium heat exchanger
• Compatible with Vaillant’s vSMART controls for smart heating management
• Easy-to-use backlit display for simple operation
• Frost protection to prevent damage in cold weather

Why we like this boiler

The ecoTEC plus stands out for its intelligent power modulation, which significantly reduces fuel costs and carbon footprint. Its compact size doesn’t compromise performance, making it an excellent choice for homes with limited space.

Moreover, Vaillant’s entire range of domestic boilers has received a Which? Best Buy award, highlighting its reliability and performance.

Alpha E-TEC Regular

Part of Alpha’s well-known E-TEC range, this is a boiler with a strong emphasis on build quality and performance. Alpha back this up with an impressive seven-year warranty.

All Alpha ETEC regular boilers benefit from a stainless steel heat exchanger that resists corrosion and reduces maintenance requirements. This boiler is particularly well-suited for homes with traditional heating systems and those requiring a separate hot water cylinder.

Outputs (kW)	Warranty	Efficiency	Price Range
15, 20, 26	7-year standard warranty	A-rated, with up to 89% efficiency rating	£650 to £950

Features

• Stainless steel heat exchanger
• Lower maintenance requirements
• Zinc-plated expansion vessel to prevent corrosion
• Built-in frost protection
• Easy access for servicing with a hinged door
• Backlit LCD display for easy monitoring and control
• Compatible with Alpha’s range of smart controls
• Low NOx Class 6 rating for reduced emissions
• Compact dimensions for flexible installation options

Why We Like It

The Alpha E-TEC Regular impresses with its durability and low maintenance needs. The stainless steel heat exchanger resists corrosion, potentially saving you money on repairs in the long run.

Viessmann Vitodens 200-W Regular

The Vitodens 200-W regular powerful gas condensing boiler is an excellent choice for larger homes. Thanks to the high-efficiency MatriX cylinder burner, it achieves up to 98% fuel efficiency, making it the most efficient conventional boiler on the market.

The 200-W has an integrated Lambda Pro Control Plus combustion controller, which also contributes to that fantastic high energy efficiency while reducing maintenance costs.

Best of all, you can control your heating from your phone. Whether you’re coming home early or staying out late, you can adjust your heating from anywhere to walk into a warm house. 

Viessmann also has the ViCare app, which allows you to check whether your boiler is working correctly. If it’s not, it can automatically contact the engineer to let them know that assistance is needed.

Outputs (kW)	Warranty	Efficiency	Price Range
49 to 99 kW, cascade up to 594 kW	2-year standard warranty, extendable to up to 5 years if installed by a Viessmann installer and 10 years if registered through the Viessmann InstallerPortal for 49 & 60 kW models only	A-rated, with up to 98% efficiency rating	£1,500 to £3,000+

Features

• Up to 98% fuel efficiency
• Much higher output than other regular boilers
• MatriX cylinder burner
• Integrated WiFi interface
• Lambda Pro Control Plus combustion controller
• ViCare app for remote monitoring
• Inox-Radial heat exchanger made of stainless steel for long-term reliability
• Weather compensation ready for optimal energy usage
• Modulation ratio of up to 1:17 for precise heating control
• Quiet operation with noise levels as low as 34 dB
• Compatible with solar thermal systems for increased sustainability
• 5-year comprehensive warranty extendable to 10 years

Why We Like It

The Vitodens 200-W is a tech-savvy choice with the best efficiency. We love the integrated WiFi and ViCare app, allowing you to control your heating remotely and get automatic engineer alerts if issues arise.

The entire Viessmann Vitodens 200 range is also a winner of the Which? Best Buy-award.

Worcester Bosch Greenstar 8000 Life Regular

The Worcester 8000 boiler comes with a 10-year warranty when installed by Worcester-accredited heating engineers.

Its robust design and high output make it an excellent choice for larger homes with more than one bathroom, where hot water and heating demands are high.

This range of boilers comes with an optional Intelligent Filling System, which continually monitors the boiler pressure and adjusts it automatically as needed. This means that your boiler will be operating at top levels of efficiency at all times.

Outputs (kW)	Warranty	Efficiency	Price Range
30, 35, 40, 45, and 50	8-year standard warranty, extendable to up to 10 years if installed with any Greenstar System Filter	A-rated, with up to 94% efficiency rating	£1,300 to £3,000

Features

• Optional Intelligent Filling System
• Up to 12-year warranty with accredited installation
• Stylish design with a full-colour TFT display
• Quiet Mark approved for whisper-quiet operation
• Compatible with Worcester Bosch EasyControl for smart heating management
• Quick to install and service with front and side access
• Robust brass components for increased durability
• Energy-saving Standby Mode when heating is not required
• Achieves an A+ ErP rating when installed with a weather-compensating control

Why We Like It

The Worcester 8000 Life offers peace of mind with its lengthy warranty. The optional Intelligent Filling System is a game-changer, ensuring your boiler always operates at peak efficiency without manual intervention.

Glow-Worm Energy Regular

Manufactured in the UK, the Energy regular boiler has been designed to be long-lasting, easy to maintain, and keep energy bills low.

The Energy series is particularly well-suited for homeowners looking for a straightforward, no-frills heating solution that doesn’t compromise on quality. Its range of outputs and focus on efficiency make it a versatile choice for various property sizes and heating requirements.

Outputs (kW)	Warranty	Efficiency	Price Range
12, 15, 18, 25, and 30	7-year standard warranty, extendable to up to 10 years if registered through Club Energy and installed with a Glow-worm Power Filter	A-rated, with up to 94% efficiency rating	£700 to £1,500

Features

• Energy-efficient operation
• Compact dimensions for flexible installation
• High-efficiency aluminium heat exchanger
• Compatible with Glow-Worm’s MiGo smart control
• Quiet Mark approved for low noise levels
• Built-in frost protection
• Simple LCD display for easy operation
• Modulating pump for increased efficiency
• 2-year parts and labour warranty, extendable to 7 years

Why We Like It

The Glow-Worm Energy offers great value for money. Its range of outputs means there’s likely a perfect fit for your home, regardless of its size. The focus on easy maintenance could save you time and money in the long run.

How Much Do Conventional Boilers Cost

Conventional boiler prices typically range from £600 to £2,500 for the unit alone. Boiler installation costs are separate and usually range from £500 to £1,500, depending on the complexity of the installation. 

While we’ve provided specific prices for the models we’ve highlighted earlier, it’s important to note that boiler costs can vary based on several factors:

• Boiler output
• Brand reputation
• Energy efficiency
• Additional features
• Installation complexity

You can also check out our New Boiler Cost Guide 2025 for more pricing information & boiler deals.

How To Choose The Right Conventional Boiler For Your Needs

Selecting the right conventional boiler is an important decision for any homeowner. This guide will walk you through the key factors to consider when going through your options.

Home Size and Hot Water Demand

Consider your home’s size and how much hot water you use. Larger homes with multiple bathrooms need more powerful boilers. Choose a boiler that can handle your peak demand without struggling.

Energy Efficiency Rating

Look for boilers with high energy efficiency ratings. More efficient models may cost more upfront but can lead to significant savings on energy bills over time.

Fuel Type

Consider the fuel type available in your area. Common options include natural gas, oil, and LPG. Choose a boiler compatible with your preferred or available fuel source.

Brand Reputation and Warranty

Opt for reputable brands known for reliability and good customer service. Check the warranty terms, as longer warranties often indicate the manufacturer’s confidence in their product.

Price

While price is important, it shouldn’t be the only factor. Balance the initial cost with long-term efficiency and reliability. Remember, a cheaper boiler might lead to higher running costs or more frequent repairs.

FAQs

What is a conventional boiler?

A conventional boiler, also called a heat-only boiler or regular boiler, is the oldest type of boiler that works with two tanks—one in your loft for cold water and a cylinder elsewhere for hot water. The cold water flows down from the tank to the boiler, where it’s heated. This hot water is then stored in the cylinder until you need it for your taps or radiators.

Conventional boilers come in two types: sealed and open-vent. Sealed systems are closed to the atmosphere and don’t require a feed and expansion tank.

Meanwhile, open-vented systems need a feed and expansion tank to manage the water loss from leakage or evaporation.

What size conventional boiler do I need? 

The size depends on your home’s heating and hot water demands, including the number of radiators and bathrooms and how well your home is insulated. As a rough guide:

• 2-3 bedrooms: 15-24kW
• 3-4 bedrooms: 24-30kW
• 4+ bedrooms: 30-40kW 

An oversized boiler wastes energy, while an undersized one won’t meet your needs, so we recommend getting a professional assessment to choose the most accurate size. 

What’s the typical lifespan of a conventional boiler? 

A well-maintained conventional boiler typically lasts 10-15 years, though some can last up to 20 years with excellent care. The actual lifespan of your boiler will depend on usage (frequent use causes more wear), maintenance (regular servicing extends life), and water quality in your area (limescale buildup in hard water areas can reduce efficiency).

Summary

Conventional boilers are a great option for larger homes that use a lot of hot water. Need multiple showers running while the dishwasher is on? A conventional boiler can handle it.

Is a conventional boiler better than a combi boiler or system boiler? Potentially yes, but they are all specific to your home’s needs.

If you’re not happy with your current system or combi boiler, there’s a conventional replacement boiler out there that can cope. But if you’d rather have no water tank, take a look at the best combi boilers for 2025. You can switch from a conventional boiler to a different type if you prefer.

A conventional boiler to combi boiler conversion will cost around £2,800, but it could save you money on your energy bills all year round, as combi boilers only heat water as and when required.

Prices vary significantly between different brands. For an accurate quote based on your needs, try our fixed price quotation service. Just provide us with some information about your heating needs and we’ll recommend the best boilers for your home.