What is a Combi
Boiler?

Written by: Energy Efficient You

Published: 12.03.2025

Introduction

So what is a combi boiler? A combi boiler, short for combination boiler, is one of the most popular heating systems in UK homes. It provides both central heating and instant hot water without needing a separate water tank, making it an efficient and space-saving choice.

But what exactly is a combi boiler, and why is it a great option for your home? In this guide, we’ll explain how it works, its key benefits, and how you could get a free upgrade to a brand-new combi boiler through a government grant.

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How Does a Combi Boiler Work?

A combi boiler is an all-in-one heating system that provides both central heating and hot water on demand. Unlike traditional boilers, it doesn’t require a separate hot water cylinder or cold water storage tank, making it compact and efficient.

When you turn on a hot tap or shower, the combi boiler instantly heats the water directly from the mains supply using a built-in heat exchanger. This means you get unlimited hot water whenever you need it, without waiting for a storage tank to refill. At the same time, the boiler also powers your radiators, keeping your home warm.

Because it only heats water when needed, a combi boiler is highly energy-efficient—helping to lower your energy bills. Plus, if you currently have an older, less efficient system, you may be eligible for a free upgrade to a combi boiler through a government grant.

Benefits of a Combi Boiler

Switching to a combi boiler comes with several advantages, making it one of the most popular choices for homeowners. Here’s why:

  • Energy Efficient: Combi boilers only heat water when needed, which reduces energy waste. In comparison to traiditonal boilers with storage tanks, you can save money on your energy bills with an upgraded combi boiler.
  • Instant Hot Water: No waiting around for a water tank to heat up! Combi boilers provide hot water on demand, ensuring you always have a steady supply for showers, baths and sinks.
  • Space Saving: Traditional boilers take up a lot of space, as they require a separate water tank. A combi boiler is a compact, all in one unit, perfect for smaller homes or flats with limited space.
  • Lower Maintenance: Combi boilers have fewer components than traditional boilers, which means that they generally require less maintenance and don’t break down as easily.
  • Environmentally Friendly: By using less energy and reducing heat waste, combi boiler help lower your home’s carbon footprint, making them a good, eco-friendly choice.
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Why Choose a Combi Boiler Over a Traditional System?

If you’re thinking about upgrading your boiler, it’s important to understand the differences between a combi boiler and traditional heating systems. Here’s why a combi boiler is often the best choice:

  • Lower Installation Costs: Traditional heating systems require multiple components, including a hot water cylinder and sometimes also a cold water storage tank. A combi boiler is a single unit, which makes installation a simpler, quicker and cheaper process.
  • Ideal for most homes: Combi boilers are perfect for small to medium sized homes, as they don’t require extra tanks or cylinders. If you have good mains water pressure and don’t need to run multiple showers at once, a combi boiler is the best option.
  • Less Risk of Frozen Pipes: Traditional heating systems rely on water tanks in the loft, which can be at risk of freezing in the winter. Combi boilers don’t need a loft tank, reducing the risk of burst pipes in cold weather.

Who Qualifies for a Free Combi Boiler Upgrade?

If you have an old, inefficient boiler, you could be eligible for a free combi boiler upgrade through a government grant. Here’s what you need to know about the qualification criteria:

  • Type of boiler: You must have a non-condensing boiler to qualify for a boiler grant.
  • Property ownership: Boiler grants are only available to homeowners.
  • Energy efficiency of the home: Your home will need a poor energy efficiency rating to qualify for a grant to install central heating. This can be an EPC (Energy Performance Certificate) of E, F, or G.
  • Benefits: You will need to be in receipt of certain benefits such as Pension credit, child tax credit, or working tax credit to be eligible for the grant.
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How To Get A Free Combi Boiler

Getting a free combi boiler upgrade is simple, and we handle everything for you. Here’s a step-by-step breakdown of how it works:

1. Check Your Eligibility: First, you’ll need to see if you qualify for the scheme. This usually depends on your income, benefits, and the condition of your current boiler. You can do this by filling out a quick online form or speaking to our team.

2. Grant Approval & Boiler Selection: Once the assessment is complete, we’ll handle the grant application on your behalf. If approved, we’ll help you choose a new, energy-efficient combi boiler that meets your home’s needs.

3. Professional Installation – Free of Charge: Our Gas Safe registered engineers will install your new boiler at no cost to you. The installation process is quick and hassle-free, usually completed within a day.

4. Enjoy the Benefits of Your New Combi Boiler: Once installed, your new combi boiler will provide instant hot water, efficient heating, lower energy bills, and require less maintenance than older boilers.

Conclusion

Upgrading to a combi boiler is a smart choice for a more efficient, reliable, and cost-effective heating system. With instant hot water, lower energy bills, and a space-saving design, it’s no surprise that combi boilers are one of the most popular options for UK homes.

If you have an old or inefficient boiler, you could be eligible for a free combi boiler upgrade through a government grant—saving you money while making your home more energy-efficient. You can check your eligibility below. 

Don’t miss out! Check if you qualify today and start enjoying the benefits of a new combi boiler for free.

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