The best conventional boilers in 2026 are the Worcester Bosch Greenstar Ri Heat Only, the Viessmann Vitodens 100-W regular, the Ideal Mexico HE, the Vaillant ecoTEC regular, and the Alpha E-Tec NX Heat Only.
These five models lead the market because they pair strong, consistent hot water performance with the proven reliability that larger households with existing tanks and cylinders genuinely need.
Below, we break down each of these boilers in detail so you know exactly what you’re paying for before booking an installation.
5 Best Conventional Boilers: A Quick Look
The best conventional boilers all pair well with an existing tank and cylinder setup, but they differ noticeably on price, warranty length, and brand reputation. Here’s a quick comparison to help you narrow things down.
| Boiler | Best For | Efficiency | Boiler Cost | Installed Cost | Warranty | Which? Rating | Trustpilot Score |
| Worcester Bosch Greenstar Ri | Overall reliability and brand trust | A-rated, 94% | £950–£1,300 | £2,200–£2,900 | 7 years, extendable to 10 | Recommended provider | 4.5/5 |
| Viessmann Vitodens 100-W Regular | Long term efficiency retention | A-rated, 94% | £1,000–£1,400 | £2,300–£3,000 | 10 years | Recommended provider | 4.6/5 |
| Ideal Mexico HE | Best value for money | A-rated, 90% | £700–£950 | £1,900–£2,500 | 7–10 years | Recommended provider | 4.4/5 |
| Vaillant ecoTEC Regular | Larger homes with several bathrooms | A-rated, 92% | £1,000–£1,400 | £2,200–£2,900 | 10 years | Recommended provider | 4.5/5 |
| Alpha E-Tec NX Heat Only | Budget friendly durability | A-rated, 91% | £750–£1,000 | £1,900–£2,400 | 10 years | Not independently tested | 4.3/5 |
5 Best Conventional Boilers: Reviewed By Our Experts
The best conventional boilers each bring something slightly different to the table, whether that’s brand trust, long term efficiency, or price. Here’s our detailed breakdown of each model.
1. Worcester Bosch Greenstar Ri: Best For Overall Reliability And Brand Trust
The Worcester Bosch Greenstar Ri Heat Only has become the conventional boiler most installers reach for when replacing an older regular boiler in a home that already has a tank and cylinder setup.
Worcester Bosch has built decades of trust through solid engineering, and this model benefits from the brand’s enormous nationwide installer network and excellent spare parts availability. It’s a dependable choice for larger families who want strong hot water performance across multiple bathrooms without constant maintenance worries.
| Feature | Detail |
| Available outputs | 12kW, 15kW, 18kW, 21kW, 24kW |
| Efficiency | A-rated, 94% |
| Warranty | 7 years, extendable to 10 |
| Boiler price | £950–£1,300 |
| Installed price | £2,200–£2,900 |
Specs and features: The unit includes a compact case design, an easy to read display, and compatibility with Worcester’s own smart thermostat range for remote heating control.
Efficiency: It carries an ErP A rating with a 94% efficiency score, a genuinely strong figure for a conventional boiler, though the heat exchanger is aluminium rather than stainless steel, meaning efficiency can decline slightly over a longer ownership period.
Estimated cost of the unit: The boiler alone typically costs between £950 and £1,300 depending on the supplier and output size.
Cost with installation: Once fitted, most households pay between £2,200 and £2,900, with pricing depending on whether the existing tank and cylinder can be reused or need replacing.
Running costs: Running costs start off competitive thanks to the strong initial efficiency rating, though homeowners planning to keep the boiler for well over a decade should expect a gradual rise in gas usage as the aluminium heat exchanger ages.
Which? and Trustpilot ratings: Worcester Bosch holds Which? Recommended Provider status and a strong 4.5 out of 5 rating on Trustpilot, with reviewers consistently praising the brand’s aftercare and long term dependability.
Should You Choose The Worcester Bosch Greenstar Ri?
Choose the Worcester Bosch Greenstar Ri if…
- You want a well known, trusted brand backed by a huge installer network
- Your home already has a functioning cold water tank and hot water cylinder
- You’re comfortable extending your warranty through a qualifying installation
- You have two or more bathrooms with regular simultaneous use
Do not choose the Worcester Bosch Greenstar Ri if…
- Your home doesn’t have loft space for a cold water tank
- You want a heat exchanger that resists efficiency loss over time
- You’re set on the longest standard warranty without any extension conditions
2. Viessmann Vitodens 100-W Regular: Best For Long Term Efficiency Retention
The Viessmann Vitodens 100-W regular consistently ranks among the best conventional boilers because it delivers premium build quality that genuinely holds its efficiency over time.
Viessmann uses a patented stainless steel Inox-Radial heat exchanger across its range, which resists corrosion far better than the aluminium alternatives found in many rival boilers and helps the unit maintain its performance for well over a decade. This model carries one of the longest standard warranties available on a conventional boiler.
| Feature | Detail |
| Available outputs | 12kW, 15kW, 19kW, 26kW |
| Efficiency | A-rated, 94% |
| Warranty | 10 years |
| Boiler price | £1,000–£1,400 |
| Installed price | £2,300–£3,000 |
Specs and features: The boiler includes a backlit display, built in wifi for fault monitoring and remote control, a wide modulation range for smooth output adjustment, and notably quiet operation.
Efficiency: It carries an A-rated efficiency of 94%, among the strongest figures in the conventional boiler category, with the added benefit of retaining that efficiency more consistently thanks to the stainless steel heat exchanger.
Estimated cost of the unit: Pricing for the boiler alone generally sits between £1,000 and £1,400.
Cost with installation: Installed costs typically range from £2,300 to £3,000, depending on cylinder condition and property layout.
Running costs: Running costs stay consistently competitive year after year thanks to the corrosion resistant heat exchanger, which avoids the gradual efficiency drop seen in boilers using cheaper materials.
Which? and Trustpilot ratings: Viessmann holds Which? Recommended Provider status and an excellent 4.6 out of 5 on Trustpilot, with customers regularly highlighting quiet operation and long term reliability as standout points.
Should You Choose The Viessmann Vitodens 100-W Regular?
Choose the Viessmann Vitodens 100-W Regular if…
- You want the longest standard warranty available in this category
- You plan to keep your boiler for well over a decade
- Quiet operation matters because your boiler sits near living space
- You value engineering quality that holds up over time
Do not choose the Viessmann Vitodens 100-W Regular if…
- You want the biggest, most recognised UK household brand name
- You need same day parts from every local plumbing merchant
- You’re prioritising the lowest unit price above all else
3. Ideal Mexico HE: Best Value For Money
The Ideal Mexico HE has earned a strong reputation as the conventional boiler that delivers genuinely solid performance without the premium price tag attached to some rival brands. It’s a particularly popular choice among landlords managing multiple rental properties with existing tank and cylinder setups who need dependable heating without overspending.
| Feature | Detail |
| Available outputs | 15kW, 18kW, 21kW, 25kW |
| Efficiency | A-rated, 90% |
| Warranty | 7–10 years |
| Boiler price | £700–£950 |
| Installed price | £1,900–£2,500 |
Specs and features: The boiler includes a simple, easy to use control panel, reliable modulation, and a compact case design that suits most standard airing cupboard installations.
Efficiency: It carries an A-rated efficiency of around 90%, slightly behind the premium brands but still comfortably above the minimum standard required under current UK regulations for new gas boiler installations.
Estimated cost of the unit: Pricing typically falls between £700 and £950, making it noticeably more affordable than the premium options on this list.
Cost with installation: Installed costs generally range from £1,900 to £2,500, which explains why it’s such a popular pick for budget conscious homeowners and landlords alike.
Running costs: With slightly lower efficiency than the top tier brands, running costs may be marginally higher over a full year, though the difference tends to be modest for most typical households.
Which? and Trustpilot ratings: Ideal holds Which? Recommended Provider status and scores 4.4 out of 5 on Trustpilot, with reviewers frequently highlighting good value for money as a key strength.
Should You Choose The Ideal Mexico HE?
Choose the Ideal Mexico HE if…
- You want strong performance without paying premium brand prices
- You’re a landlord managing several rental properties on a budget
- Your existing tank and cylinder are still in good working condition
- You value a solid warranty at a lower price point
Do not choose the Ideal Mexico HE if…
- You want the absolute highest efficiency figure available
- You’re set on a premium European engineering brand
- Quiet operation is your single biggest priority
4. Vaillant ecoTEC Regular: Best For Larger Homes With Several Bathrooms
The Vaillant ecoTEC regular is the conventional boiler we recommend most often for larger households with two or more bathrooms in frequent simultaneous use, since it pairs proven German engineering with a genuinely strong output range.
Vaillant has a long standing reputation in the UK market for dependable, easy to service heating appliances, and this model reflects that history with reliable performance well suited to a busy family home. It’s a genuinely popular upgrade path for households replacing an older, less efficient regular boiler.
| Feature | Detail |
| Available outputs | 12kW, 15kW, 18kW, 24kW |
| Efficiency | A-rated, 92% |
| Warranty | 10 years |
| Boiler price | £1,000–£1,400 |
| Installed price | £2,200–£2,900 |
Specs and features: The boiler includes an intuitive control interface, wifi connectivity for remote scheduling, and reliable modulation across a wide output range to suit varying property sizes.
Efficiency: It carries an A-rated efficiency of roughly 92%, a strong figure that sits comfortably within the top tier of conventional boilers suited to larger UK homes.
Estimated cost of the unit: Expect to pay between £1,000 and £1,400 for the boiler alone.
Cost with installation: Installed pricing typically runs from £2,200 to £2,900, depending on cylinder condition and any pipework changes required.
Running costs: Running costs sit broadly in line with other A-rated conventional boilers in this bracket, and because hot water is stored in advance rather than heated on demand, performance stays consistent even when multiple bathrooms are used at the same time.
Which? and Trustpilot ratings: Vaillant holds Which? Recommended Provider status and scores 4.5 out of 5 on Trustpilot, with reviewers often mentioning easy servicing and dependable long term performance.
Should You Choose The Vaillant ecoTEC Regular?
Choose the Vaillant ecoTEC Regular if…
- Your home has two or more bathrooms in regular simultaneous use
- You want proven German engineering with a strong UK track record
- You’re happy to keep your existing tank and cylinder setup
- You value easy servicing and accessible spare parts
Do not choose the Vaillant ecoTEC Regular if…
- Your home only has one bathroom with light hot water demand
- You want the lowest possible unit price on this list
- You’d rather remove your loft tank and switch to a combi boiler
5. Alpha E-Tec NX Heat Only: Best Budget Friendly Durability
The Alpha E-Tec NX Heat Only has earned its spot on this list by proving that a lower price doesn’t automatically mean a lower quality build.
Alpha Heating Innovation has built a solid reputation for producing boilers with genuinely durable internal components, and this model uses a zinc plated vessel designed to resist corrosion far longer than untreated standard parts found in some budget rivals. It’s a smart pick for homeowners who want dependable performance for a larger home without spending on brand premium.
| Feature | Detail |
| Available outputs | 15kW, 18kW, 25kW |
| Efficiency | A-rated, 91% |
| Warranty | 10 years |
| Boiler price | £750–£1,000 |
| Installed price | £1,900–£2,400 |
Specs and features: The boiler includes a zinc plated vessel for corrosion protection, a straightforward digital display, and reliable modulation that adjusts output to match real time demand.
Efficiency: It carries an A-rated efficiency of around 91%, a genuinely solid figure that keeps it competitive with pricier brands on this list despite the lower unit cost.
Estimated cost of the unit: The boiler alone typically costs between £750 and £1,000, among the more affordable options on this list.
Cost with installation: Installed pricing generally runs from £1,900 to £2,400, sitting comfortably at the lower end of this comparison group.
Running costs: Running costs are broadly comparable to the Ideal Mexico HE given the similar efficiency band, making it a sensible option for households and landlords watching their energy spend closely.
Which? and Trustpilot ratings: Alpha has not been independently tested by Which? in the same depth as some larger brands, but it holds a solid 4.3 out of 5 on Trustpilot, with reviewers often praising durability and value for money.
Should You Choose The Alpha E-Tec NX Heat Only?
Choose the Alpha E-Tec NX Heat Only if…
- You want genuine quality without paying premium brand prices
- You’re comfortable with a lesser known but well engineered brand
- You want corrosion resistance for long term durability
- Budget is a real consideration but you don’t want to compromise on build quality
Do not choose the Alpha E-Tec NX Heat Only if…
- You want a boiler independently tested by Which?
- Brand recognition matters to you for future resale value
- Your household has particularly heavy hot water demand across several bathrooms
How We Choose The Best Conventional Boilers
We chose the best conventional boilers by combining hands-on installation experience gathered from fitting boilers in larger UK family homes with existing tank and cylinder setups, alongside independent data from trusted third party sources. As nationwide installers working with homeowners and landlords every single day, our recommendations reflect what genuinely performs well in real households, not just impressive sounding spec sheets.
- Verified manufacturer data on efficiency, output, and warranty terms directly against official documentation from Worcester Bosch, Viessmann, Ideal, Vaillant, and Alpha
- Cross referenced independent scoring from Which? and Trustpilot to balance technical performance against genuine customer satisfaction
- Drew on feedback from our own Gas Safe registered installer team, who fit these exact models regularly in UK properties with existing conventional systems
- Compared unit and installed pricing across multiple UK suppliers to ensure figures reflect real market conditions rather than inflated list prices
- Prioritised boilers genuinely suited to homes with two or more bathrooms, since this is where a conventional boiler’s stored hot water advantage matters most
- Considered the needs of both homeowners and landlords, including larger rental properties where several occupants depend on consistent hot water pressure
How To Choose The Best Conventional Boiler For Your Property
Choosing the best conventional boiler for your property comes down to understanding whether your existing tank and cylinder setup, along with your household’s hot water habits, genuinely suit this boiler type. Work through this checklist before making your final decision.
- Confirm you actually need a conventional boiler. They suit homes with an existing cold water tank in the loft and a hot water cylinder, particularly properties with two or more bathrooms used simultaneously
- Check the condition of your existing tank and cylinder, since a genuinely old or corroded cylinder may need replacing alongside the boiler, adding to overall project cost
- Consider your mains water pressure, since conventional boilers work well even with lower incoming pressure because hot water is stored in advance rather than heated on demand
- Compare warranty terms carefully, since some manufacturers require an accredited installer condition to activate extended cover, while others offer the full term with no strings attached
- Think about your household size and bathroom count, since conventional boilers genuinely shine in larger homes where several people need hot water at the same time
- Factor in your total budget for the boiler, any required tank or cylinder replacement, and installation together, as these costs vary depending on your existing setup’s condition
- Ask about smart thermostat compatibility if you want to manage your heating remotely across a larger property with more rooms to control
- Get a proper home survey before committing, since correctly sizing a conventional boiler for your radiators, bathroom count, and cylinder capacity is essential for reliable long term performance
Ready to Upgrade Your Conventional Boiler?
If your current conventional boiler is becoming unreliable, expensive to run, or struggling to keep up with your household’s hot water demand, replacing it with a modern, high-efficiency model could improve comfort while reducing your energy bills.
Whether you’re replacing an ageing heat-only boiler or upgrading an existing tank and cylinder system, choosing the right boiler is only part of the process. Professional installation is just as important to ensure reliable performance for years to come.
At Eazy Heat, we install new conventional boilers for homeowners and landlords across the UK. Our straightforward online quotation tool gives you a clear, no-obligation price in just a few simple steps, with no home visit required to get started.
Every installation is carried out by experienced engineers and comes with a market-leading 12-year parts and labour warranty, giving you complete peace of mind long after your new boiler has been fitted.
If you’re ready to replace your conventional boiler, get your free online quote today and discover how quick and hassle-free a new boiler installation with Eazy Heat can be.
FAQs
Can a conventional boiler be converted to a combi boiler during replacement?
It’s entirely possible to switch from a conventional boiler to a combi boiler during a replacement, provided your mains water pressure is strong enough to support it, which also frees up loft and airing cupboard space by removing the tank and cylinder. This decision is worth discussing with your installer, since it depends heavily on your household’s hot water demand and existing pipework layout.
Do conventional boilers need a pump separate from the boiler unit?
Some older conventional boiler systems use a separate circulating pump to move hot water around the radiators, though most modern conventional boilers now include this pump built into the unit itself, simplifying both installation and future servicing. It’s worth checking whether your existing pump needs replacing alongside the boiler if it’s original to a much older system.
How does a conventional boiler cope with a power cut compared to other boiler types?
Conventional boilers still require electricity to run the pump and controls, so they won’t work during a power cut, though the stored hot water in the cylinder may retain some warmth for a short period afterwards. This is similar to combi and system boilers, since virtually all modern gas boilers rely on an electrical supply to function safely.
Is it normal for a conventional boiler’s hot water cylinder to need re-insulating over time?
Older hot water cylinders can lose insulation effectiveness over the years, leading to heat loss and higher running costs even with an efficient new boiler installed. Fitting a modern, well insulated cylinder jacket or upgrading to a factory insulated cylinder alongside a boiler replacement can noticeably reduce standing heat loss.
Can a conventional boiler be used alongside solar thermal water heating?
Conventional boilers integrate well with solar thermal systems because the hot water cylinder can be pre-heated by solar panels before the boiler tops up any shortfall, which can meaningfully reduce gas usage during sunnier months. This combination is more straightforward to set up with a conventional boiler than with a combi boiler, since the cylinder provides the necessary storage buffer for solar input.