If your current boiler is a regular (or conventional) system, it likely uses a hot water cylinder and possibly a cold water tank in the loft. These systems store hot water in advance, which means you can run out and have to wait for it to heat up again. A combi boiler, on the other hand, delivers hot water instantly from the mains—no tank, no waiting. It can free up space in your home, reduce energy bills, and require less maintenance thanks to its modern, streamlined design. Unless your home has unusually high water demand, upgrading to a combi boiler could be a smarter, more efficient choice for your everyday comfort and long-term savings. A new combi boiler is typically around 90% efficient, so upgrading from an old back boiler could save you up to £380 a year on your energy bills.

Instant Hot Water, No Heat Loss
Unlike traditional boilers that heat and store water in tanks—often causing heat loss over time—Baxi combi boilers heat water only when it’s needed. This on-demand system eliminates energy waste from stored water.

Advanced Condensing Technology
Modern combi boilers such as the Baxi 800, Vaillant ecoTEC Plus, Worcester Greenstar 8000, and Ideal Logic+ use condensing technology to capture and reuse heat from flue gases (waste vapor). This boosts energy efficiency to between 90% and 98%, compared to just 70%–80% for older conventional boilers.

Real Savings on Energy Bills
Replacing an old boiler with a new A-rated combi boiler could save you up to £315 per year. Other estimates suggest savings of up to £511 annually, based on the average UK household energy bill of around £1,277. Depending on your household’s usage, a combi boiler could reduce your heating bills by 25% to 40%. Plus, you may be eligible for a free boiler grant through the ECO4 scheme with help from Heat1.

Choosing the ECO4 Scheme to install a new boiler in your home is a smart decision for both your wallet and the environment. The scheme is designed to help homeowners reduce their energy bills by providing financial support for energy-efficient heating systems. By upgrading to a new boiler through ECO4 grant, you can benefit from improved heating performance, lower carbon emissions, and increased comfort in your home. Additionally, the scheme often covers all of the installation costs, making it more affordable to switch to a greener and more efficient heating solution. This not only helps you save money in the long run but also contributes to the wider goal of reducing carbon footprints and promoting sustainable living.

To qualify for a free boiler grant under ECO4, your household typically needs to meet one or more of the following criteria:

If you’re unsure whether you qualify, it’s easy to check your eligibility with our free online tool — determine your eligibility in just 60 seconds.

Under the ECO4 scheme, eligible households can receive:

• A free combi boiler
• You’ll receive professional installation by our certified engineers
• System upgrades such as thermostatic radiator valves (TRVs), smart controls, and pipe insulation
• A full home energy assessment to identify other opportunities for improvement (e.g., insulation or heating system)

This holistic approach means that your home won’t just get a new boiler — it’ll become more energy efficient overall.

These top UK brands stand out for their energy efficiency, innovation, and customer satisfaction.

1. Worcester Bosch
   A long-trusted name since the 1960s, Worcester Bosch offers boilers with up to 94% efficiency, excellent warranties (up to 12 years), and strong aftercare. They’ve won the ‘Which? Best Buy’ award 14 years in a row and even hold a Royal Warrant.
2. Baxi
   With roots dating back to the 1860s, Baxi offers compact, energy-efficient boilers (up to 93%) that are easy to install. Features include smart controls, magnetic filters, and eco-friendly designs at competitive prices.
3. Vaillant
   This German brand is known for high-efficiency boilers and smart technology. Their quiet, ErP A-rated boilers offer quick hot water delivery and can be controlled remotely using the vSMART app.
4. Ideal Heating
   Ideal has been serving UK homes since 1906, offering compact, energy-saving boilers with Quiet Mark certification. They focus on low-carbon solutions and provide extended warranties of up to 12 years.
5. Viessmann
   A global leader in heating, Viessmann is praised for its advanced engineering and durable stainless steel parts. Their boilers reach up to 98% efficiency and support renewable energy systems.

Each of these brands offers reliable, efficient combi boilers that meet a variety of home heating needs. Plus, all these boilers are available through Heat1 with support from government grants.

Check Eligibility

See if you qualify for the ECO4 scheme based on income, property type, and your current boiler’s age or efficiency using Heatzen’s free online checker.

Apply Online

Fill out the application on Heatzen’s website with your household and heating details. Our team will review it for eligibility.

Free Home Survey

If approved, a Heatzen expert will visit to assess your heating needs and provide a quote.

Boiler Installation

Schedule a free installation. Heatzen will remove your old boiler and install the new one, connecting it to your system.

Beyond saving money on energy bills, upgrading to a boiler grant can significantly increase the value and appeal of your property. As energy efficiency becomes a top priority for UK homebuyers, installing a modern A-rated combi boiler demonstrates a long-term investment in sustainability. Potential buyers are increasingly attracted to homes with upgraded heating systems that offer lower running costs and require less maintenance. A best combi boiler installation—especially one supported by the ECO4 scheme—can boost your home’s Energy Performance Certificate (EPC) rating, making it more attractive on the property market. Whether you’re planning to sell in the near future or simply want to future-proof your home, switching to a combi boiler is a strategic upgrade that adds both financial and environmental value.

Making the switch from a regular boiler to a combi boiler is a smart investment that can lower your energy bills, save space, and improve your home’s overall efficiency. While the upfront cost can be several thousand pounds, the long-term savings and added comfort make it well worth it. Thanks to the ECO4 scheme, eligible UK households can access this upgrade with little to no upfront cost. In a time of rising energy prices and increasing climate concerns, making the switch isn’t just a smart decision — it’s a responsible one. For more details about boiler grants, you can visit the Heat1.co.uk website.