Best Cheap Combi Boilers 2026

For those who have tried to apply for boiler grants and been unsuccessful, you may be in the market for an affordable, dare we say it, budget-friendly combi boiler.

Before we proceed with affordable combi boilers in the UK, let’s define what we mean by ‘cheap boilers’.

What Does A Cheap Boiler Mean In The UK Market?

The term “cheap” can mean different things to different people.

However, there is a price range that many will accept as inexpensive.

Generally speaking, a cheap combi boiler, without installation, can cost between £600 and £1,000.

According to Checkatrade, the average cost for installing a combi boiler is between £1,000 and £2,000.

The wide variation between installation costs can be attributed to several factors, such as:

Property-Related Factors

If you want a simple replacement, installation costs will remain low. However, if you’re planning on:

• Relocating your boiler;
• Needing to upgrade your gas pipework;
• Have to install a booster pump to increase water pressure;
• Or live in a large property.

These factors will start to increase your installation costs.

Additional System Accessory

For homeowners who haven’t upgraded their boiler system in some years, you may need to install some new accessories, which include:

• Condensate pipework;
• Smart controls;
• New thermostats;
• Filters;
• And perhaps have the old system’s cylinder removed.

Labour And Compliance Factors

It shouldn’t come as a surprise, but expertise comes at a price.

Additionally, labour rates can vary depending on where you live.

Other contributing factors that will increase labour costs include:

• Complexity of the task and the time required;
• New building regulations that need to be met;
• If the work requires access to scaffolding;
• And if the Gas Safe registered engineer needs to dispose of the old boiler and associated waste.

Now that we know what could potentially drive up the costs of installing a cheap boiler, what should you be looking for when choosing one?

What Factors Should I Look At When Buying A Cheap Combi Boiler?

When purchasing a less expensive boiler, it’s arguably more important to conduct thorough research.

After all, even cheaper combi boilers can last up to 10 to 15 years with the correct usage and care.

Here are a few factors to research when buying a new cheap combi boiler:

Boiler Size And Output (kW)

It’s essential to select a boiler that is the correct size and has the right power output in kilowatts (kW) to ensure optimal performance.

Generally, you can match your boiler size needs to your home:

• 24 and 28 kW are great for a flat with a single bathroom.
• 28 and 35 kW are ideal for small to medium-sized homes with two bathrooms.
• 35 and 42 kW are perfect for larger homes with two or more bathrooms.

While going for an affordable unit is a good idea, going too cheap and undersizing means you’ll be living with a weak hot water flow, and oversizing wastes money and fuel.

Efficiency And Running Costs

All new boilers must be A-rated (with an efficiency of 92% or higher) under the ErP regulations.

While these new systems are incredibly efficient, finding a model that’s a bit more expensive but an efficient boiler can save you between £100 and £300 a year on gas bills versus a budget unit that’s less efficient over time.

Warranty & Support

Cheap boilers often come with shorter warranties (2–5 years).

Look for a unit with at least a 5-year warranty, which can ideally be extended to 7–10 years if installed by an approved engineer.

A short warranty may mean a higher risk of expensive repairs later.

Now that we’ve gone over what to look for, let’s talk about the best cheap combi boiler in the UK.

Best Cheap Combi Boilers In The UK

Using the criteria mentioned above, let’s list our top choices for the best cheap combi boiler in the UK:

Baxi 600 Combi 2

The Baxi 600 Combi 2 is a really solid mid-range choice.

As you’d expect, the Baxi 600 comes in different sizes, from 24 kW up to 36 kW, and the combi version in particular stands out as one of the best boilers you can get for under £1,000.

Despite being compact enough to fit neatly into most kitchen cupboards, it still delivers strong hot water flow rates.

You also receive a seven-year warranty as standard, which provides ample peace of mind for the price.

It’s well-suited to small and medium-sized homes where you want dependable performance without breaking the bank.

Additionally, it features Baxi’s EasyFill top-up system, which makes topping it up easy, as well as being compatible with the brand’s uSense smart thermostat system.

For homes with smaller spaces, you can opt for the Baxi 400, which is more compact than the larger 600 model.

Alpha E-Tec Series

Another name that frequently appears in the “affordable but reliable” category is Alpha, specifically their E-tec Series.

The E-tec range includes models with outputs of 28 kW, 33 kW, and even a more powerful 38 kW, allowing you to match the output to your home’s specific needs.

The 28 kW model, in particular, is very competitively priced, typically costing around £750 (excluding installation) for the unit, and still comes with a stainless-steel heat exchanger, front-facing service access, and a 7-10 year warranty.

The hot water flow is also impressive for the price, making it a great all-around option for small to medium-sized homes.

Navien NCB

The Navien NCB 300, which tends to fly under the radar in the UK, is worth a look.

It offers higher output options of 28, 30, 37 and 41kW.

With such a wide variety of kW options, it’s excellent for medium-sized homes where hot water demand is more intense.

Navien builds in good modulation ratios and stainless-steel components, and it’s known for excellent flow rates compared to many rivals at the same price point.

If you want something that balances affordability with more power, the NCB 300 could be a smart buy.

However, it needs to be mentioned that saving some pennies now could mean paying for it later.

Why “Cheap” Can Cost More Later

Before you decide to go with a cheaper combi boiler, let’s review some downsides:

Running Costs

A less efficient, cheaper boiler may cost more in fuel over its lifespan.

While it is only a few efficiency percentage points off higher-priced models, over time, it can quickly add up.

Maintenance And Repairs

We’ve mentioned the importance of a good warranty.

However, shorter warranties can mean that the boiler has components with planned obsolescence or parts designed to fail over time.

Additionally, cheaper components can result in higher repair or replacement costs.

Suitability

An underpowered boiler will result in poor hot water flow or frequent cycling, which shortens its lifespan and reduces efficiency.

If you are keen to install a more expensive boiler, you can always spread the cost with a flexible finance plan.

Don’t Break The Bank Finance

Investing in a more advanced boiler doesn’t have to mean draining your savings all at once.

Instead of paying a large lump sum upfront, you can spread the cost into manageable monthly instalments.

This approach makes it easier to upgrade to a premium, energy-efficient boiler that delivers long-term savings on your energy bills while keeping your home reliably warm.

WarmZilla offers a wide choice of finance packages that include:

• Affordable monthly repayments
• Instant online quotes
• Fixed rates for peace of mind
• Flexible terms to suit your budget
• Installation by a trusted Gas Safe registered engineer

If you’re considering making the switch to a more efficient boiler, take our quick boiler survey today.