Choosing a new boiler isn’t exactly the most thrilling task on your to-do list, is it? It’s right up there with sorting out your taxes or untangling Christmas lights.
- [1] Choosing the Right Type of Boiler
- [2] Size Matters: Getting the Right Boiler Output
- [3] Efficiency Ratings: Save Money and the Planet
- [4] Budget and Costs: What to Expect
- [5] Brand and Reliability: Who to Trust
- [6] Warranty: Why Longer Means Better
- [7] Why Installation Quality Is Just As Important as the Boiler
- [8] Smart Features and Future-Proofing
- [9] Common Pitfalls to Avoid
But here’s the thing: a good boiler keeps your home warm, your showers hot, and your energy bills from giving you a heart attack. Get it wrong, and you’re stuck with a clunky, inefficient money pit that leaves you shivering on a Monday morning.
At Heatable, we’ve helped thousands of homeowners across the UK find their perfect boiler, and we’re here to guide you through the process.
This guide covers everything you need to know to choose the best boiler for your home, from sizing and fuel types to efficiency ratings and smart controls. We’ll even throw in a few tips to avoid common pitfalls.
Ready? Let’s dive in…
Key Takeaways at a Glance:
Choose between combi, system, or regular boilers based on your home size and water usage.
Always check the boiler’s warranty length - aim for 7+ years.
Match the boiler output (kW) to your number of bathrooms and radiators.
Don’t forget aftercare: annual servicing is required to keep warranties valid.
Consider fuel type: gas is cheapest, but electric and hydrogen-ready options are future-proof.
Top UK brands in 2025 include Worcester Bosch, Viessmann, and Ideal.
Smart thermostats and controls can cut bills by up to 15%.
Watch out for hidden costs like pipe upgrades or cylinder installation.
Use a Gas Safe engineer to protect your warranty and safety.
[1] Choosing the Right Type of Boiler
There are two key decisions to make: the boiler design (combi, system, or regular) and the fuel type (gas, oil, LPG, or electric). The right combo depends on your home size, layout, and location.
Over 80% of new boilers installed in the UK are combi boilers - thanks to their compact design and ease of installation, while around 85% of UK homes use natural gas for heating.
Oil supplies about 4%, mostly in rural areas, while LPG and electric boilers make up a smaller share but are growing due to eco-conscious buyers and off-grid needs.
Combi Boilers
These compact units heat water on demand straight from the mains - no hot water tank needed.
Best for: Flats or small to medium homes (1–3 beds, 1–2 baths)
Pros:
Instant hot water
No loft tank or cylinder
Cheaper to install
Cons:
Not ideal for homes with multiple bathrooms
Mains pressure dependent
Heatable Tip: If you’ve got a small household and decent mains water pressure, a combi is usually your best bet. Popular models like the Worcester Bosch Greenstar 4000 or Viessmann Vitodens 050-W are cracking choices.
System Boilers
They store hot water in a cylinder, but don’t need a loft tank.
Best for: Homes with higher hot water demand or multiple bathrooms
Pros:
Supports multiple taps at once
Works well with solar thermal systems
Cons:
Needs cupboard space for cylinder
Hot water is limited to stored amount
Top Pick: Ideal Logic Max System
Heatable Tip: If your family is constantly fighting over the shower, a system boiler (like the Ideal Logic Max System) paired with an unvented cylinder will keep everyone happy. Check if your airing cupboard has room for the cylinder before committing.
Regular (Heat-Only) Boilers
Traditional models with both a cylinder and loft tank. Suited to older homes or where water pressure is low.
Best for: Large or older homes with legacy heating systems
Pros:
Handles low pressure well
Compatible with older radiators
Cons:
Bulky and less efficient
Heatable Tip: If your home already has a regular boiler setup and you’re not planning a major overhaul, stick with it. Brands like Baxi and Vaillant offer reliable heat-only models. But if you’re starting fresh, combi or system boilers are usually more practical.
Prefer watching? Watch our 2025 boiler review on YouTube for expert picks and honest insights:
Gas, Oil or Electric?
Gas Boilers
Best for: Homes connected to the mains gas network (most urban and suburban areas).
Pros: Cheapest fuel type, widely available, highly efficient (modern condensing boilers hit 90 %+ efficiency).
Cons: Gas prices can fluctuate, and it’s a fossil fuel, so not the greenest option.
Popular brands: Worcester Bosch, Viessmann, Ideal, Baxi.
Oil Boilers
Best for: Rural homes off the gas grid.
Pros: Reliable heat source, modern condensing oil boilers are efficient.
Cons: Requires an oil storage tank, fuel deliveries can be a hassle, and oil is pricier than gas.
Heatable Tip: Check out the Grant Vortex range for top-notch oil boilers. Make sure you’ve got space for a tank and a supplier nearby.
LPG Boilers
Best for: Off-grid homes with no oil tank space.
Pros: Cleaner than oil, works like a gas boiler but uses bottled propane.
Cons: LPG is expensive, and you’ll need regular bottle deliveries or a tank.
Heatable Tip: LPG boilers are niche, but Worcester Bosch and Vaillant offer solid options if this is your only choice.
Electric Boilers
Best for: Flats or small homes with no gas/oil access, or eco-conscious households.
Pros: No emissions at point of use, compact, easy to install, no flue needed.
Cons: Electricity is pricier per kWh than gas, and running costs can be high unless paired with solar panels or off-peak tariffs.
Heatable Tip: Consider the EHC Fusion Comet for a reliable electric boiler, but crunch the numbers on running costs first. If you’re eyeing a heat pump instead, we can point you in the right direction.
[2] Size Matters: Getting the Right Boiler Output
A boiler that’s too small will leave you with lukewarm radiators and chilly toes. One that’s too big will waste energy and money.
Boiler size is measured in kilowatts (kW), and the right output depends on your home’s size, insulation, and hot water needs.
How to Estimate Boiler Size
Small homes/flats (1-2 bedrooms, 1 bathroom): 24-28 kW combi boiler.
Medium homes (3-4 bedrooms, 1-2 bathrooms): 28-34 kW combi or system boiler.
Large homes (4+ bedrooms, 2+ bathrooms): 35-42 kW system or regular boiler.
Hot water demand: For combi boilers, check the flow rate (litres per minute) to ensure it meets your needs. For example, a family with two showers might need a flow rate of 12-15 L/min.
Factors to Consider
Number of radiators: Count them! A rough guide is 1.5-2 kW per radiator.
Insulation: Well-insulated homes (double glazing, cavity wall insulation) need less power.
Bathroom usage: If you love long baths or have a rainfall shower, factor in higher hot water demand.
Location: Homes in colder parts of the UK (hello, Scotland!) may need a bit more grunt.
Heatable’s Boiler Sizing Tool:
Not sure where to start? Our online boiler quoting tool takes the guesswork out. Answer a few questions about your home, and we’ll recommend the perfect boiler size and model, complete with a fixed-price quote. It takes 90 seconds, and you don’t even need to dig out your tape measure.
[3] Efficiency Ratings: Save Money and the Planet
Modern boilers are condensing, meaning they capture and reuse heat that would otherwise escape. Look for the ErP (Energy-related Products) rating - A-rated boilers are the most efficient (90%+), while G-rated ones belong in a museum.
According to the Energy Saving Trust, here’s the potential savings you could make depending on your current boiler rating and property type:
Old Boiler Rating: | Bungalow | Detached House | Flat (Mid-Floor) | Semi-Detached House | Mid Terrace House |
G (<70% efficient) | £345 | £640 | £150 | £385 | £320 |
F (70-74% efficient) | £245 | £460 | £100 | £275 | £225 |
E (74-78% efficient) | £195 | £370 | £80 | £220 | £180 |
D (78-82% efficient) | £150 | £295 | £60 | £170 | £140 |
Why Efficiency Matters:
Lower bills: An A-rated boiler could save you £100-£300 a year compared to an old G-rated model.
Eco-friendly: Less fuel burned = lower carbon emissions.
Future-proofing: New UK regulations are phasing out inefficient boilers, so go for A-rated to stay compliant.
Heatable’s Top Picks for Efficiency
Worcester Bosch Greenstar 4000: A-rated, quiet, and built to last.
Viessmann Vitodens 100-W: Super-efficient with smart controls included.
Ideal Logic Max Combi: Great value with a long warranty.
Boost Efficiency with Smart Controls:
Pair your boiler with a smart thermostat (like Nest, Hive, or Tado) or load-compensating controls to fine-tune your heating.
These adjust the boiler’s output based on your home’s temperature, saving up to 15% on fuel. Some boilers, like the Viessmann Vitodens range, come with built-in smart tech for even easier savings.
[4] Budget and Costs: What to Expect
Boiler costs vary based on type, size, brand, and installation complexity. Here’s a rough guide (including VAT and standard installation):
Combi boiler: £1,800-£3,500
System boiler: £2,000-£4,000 (plus cylinder costs)
Regular boiler: £2,200-£4,500 (plus tank/cylinder costs)
Electric boiler: £1,500-£3,000
Oil/LPG boiler: £2,500-£5,000 (plus tank costs)
Hidden Costs to Watch For:
Pipework upgrades: Older systems may need new pipes or a power flush (£300-£600).
Radiator replacements: Budget £100-£200 per radiator if they’re outdated.
Smart controls: £150-£400 for a smart thermostat.
Warranty extensions: Some brands offer 10+ year warranties for an extra fee.
Heatable’s Fixed-Price Promise:
With Heatable, what you see is what you pay. Our online quotes include everything - boiler, installation, VAT, and even a free filter to protect your system. No nasty surprises, just a warm home and a happy wallet.
[5] Brand and Reliability: Who to Trust
Not all boilers are created equal. Stick to reputable brands with strong warranties and good aftercare.
Choosing a boiler with real-world recognition is a smart move. Here’s what to look for:
Independent Awards:
Which? Best Buy: Worcester Bosch, Viessmann, and Vaillant often rank highest for reliability and customer satisfaction.
Energy Saving Trust endorsements: Indicates proven energy efficiency and emissions reductions.
Real Customer Reviews:
Don’t just rely on star ratings - dig into Trustpilot, Google Reviews, and MoneySavingExpert forums to see how brands treat customers after installation.
Look for feedback on service response times, not just performance out of the box.
Pro tip: A boiler is only as good as the company backing it. Choose a brand that won’t ghost you when you need support.
Heatable Tip: Check Warranty Fine Print:
Some warranties require annual servicing to stay valid, so factor in £80-£150 per year for maintenance. Also, choose a Gas Safe registered installer (like our Heatable pros) to ensure your warranty isn’t voided.
[6] Warranty: Why Longer Means Better
A boiler is a big investment, so make sure it’s covered.
Look for warranties of 7–12 years. These aren’t just marketing numbers; they’re a signal of manufacturer confidence and build quality.
Brands like Worcester Bosch, Ideal, and Viessmann all offer extended warranties when installed by accredited partners.
Annual servicing is usually required to maintain cover - budget £80–£150 per year.
Why it matters:
A longer warranty saves you hundreds (if not thousands) on potential repairs. And if you’re selling your home, a boiler still under warranty can add buyer confidence and resale value.
[7] Why Installation Quality Is Just As Important as the Boiler
Even the best boiler will underperform if it’s installed incorrectly. Poor pressure balancing, faulty flue angles, or rushed fittings can all wreck efficiency - or worse, invalidate your warranty.
Here’s what to insist on:
A Gas Safe Registered engineer (legally required for all gas installations in the UK)
Full commissioning paperwork and benchmark certification
Proof of manufacturer accreditation, if required for extended warranties
How Heatable Takes the Stress Out of Installation
We don’t just sell boilers - we deliver peace of mind.
Every installer we use is Gas Safe registered, fully vetted, and rated for customer service.
We’re a Which? Trusted Trader, so you know you’re getting a verified, reliable tradesperson.
We offer a 12-month workmanship warranty on all installs - so if anything’s not perfect, we’ll put it right.
No calls. No hassle. No nonsense. Just a warm home and a boiler you can count on.
[8] Smart Features and Future-Proofing
Boilers aren’t just about heat anymore - they’re getting smarter. Look for these features to future-proof your investment:
Smart connectivity: Control your heating via an app, saving energy when you’re out.
Weather compensation: Adjusts boiler output based on outdoor temperature.
Hydrogen-ready boilers: Some models (e.g., Worcester Bosch Greenstar 4000) can switch to hydrogen blends, aligning with the UK’s net-zero goals.
Compatibility with renewables: System boilers can pair with solar thermal or heat pumps for greener heating.
[9] Common Pitfalls to Avoid
Buying based on price alone: A cheap boiler might cost more in repairs or inefficiency.
Ignoring your home’s needs: Don’t slap a combi in a mansion or a regular boiler in a tiny flat.
Skipping professional advice: A Gas Safe engineer can spot issues (like pipework or pressure problems) before installation.
Forgetting about servicing: Regular maintenance keeps your boiler efficient and extends its lifespan (12-15 years on average).
Final Thoughts
Choosing a boiler doesn’t have to be a headache. By understanding your home’s needs, picking the right type and size, and sticking with a trusted brand, you’ll be sorted for years of cosy winters.
At Heatable, we’re here to take the stress out of the process with transparent pricing, expert advice, and next-day installations.
Next Steps For Your New Boiler Journey:
When planning to install a new boiler for your home, there are several important factors to consider. Make sure to refer to the following guides to help you make informed decisions:
To dive deeper into these topics, head over to our advice section or check out our YouTube channel to learn more.
Get a Quote for a New Boiler Today
If you’re aiming to get the best deal on a new boiler, consider getting a quote from us. Here’s why:
Gas Safe installation within 24 hours.
Thousands of satisfied customers with an average score of 4.9 on Trustpilot, surpassing the market leader.
Which? Trusted Trader: Heatable is proudly recognised as a Which? Trusted Trader.
Price match guarantee: We will match any like-for-like cheaper quote.
Flexible payment options, including interest-free finance*.
Up to a 12-year guarantee on selected boilers.
Fixed price guarantee: No hidden costs.
Save your quote and decide later.
Get an instant fixed price on a new boiler here.
To learn more about boilers, visit our advice section, check out our YouTube channel, or read customer testimonials here.
Heat Happy.
