The best small boilers in 2026 are the Worcester Bosch Greenstar CDi Compact, the Viessmann Vitodens 050-W, the Intergas Compact ECO RF, the Ideal Logic Plus, and the Glow-worm Compact.
These five models lead the compact boiler category because they squeeze genuinely strong heating performance into a noticeably smaller case, making them ideal for flats, small kitchen cupboards, and properties with limited installation space.
Below, we break down each of these boilers in detail so you can pick the right one for your tight installation space.
5 Best Small Boilers: A Quick Look
The best small boilers all offer a genuinely reduced case size, but they differ noticeably on exact dimensions, output, and price. Here’s a quick comparison to help you narrow things down.
| Boiler | Best For | Dimensions (H x W x D) | Efficiency | Boiler Cost | Installed Cost | Warranty | Trustpilot Score |
| Worcester Bosch Greenstar CDi Compact | Smallest overall case size | 690 x 390 x 280mm | A-rated, 94% | £900–£1,200 | £2,000–£2,600 | 7–10 years | 4.5/5 |
| Viessmann Vitodens 050-W | Best selling compact boiler | 700 x 400 x 350mm | A-rated, 94% | £790–£1,190 | £1,900–£2,500 | 10 years | 4.6/5 |
| Intergas Compact ECO RF | Simplicity and fewer moving parts | 700 x 410 x 350mm | A-rated, 93% | £850–£1,150 | £1,900–£2,500 | 10 years | 4.3/5 |
| Ideal Logic Plus | Best value compact boiler | 700 x 395 x 280mm | A-rated, 91% | £700–£950 | £1,700–£2,300 | 10–12 years | 4.4/5 |
| Glow-worm Compact | Budget friendly small footprint | 710 x 390 x 279mm | A-rated, 92% | £650–£900 | £1,700–£2,200 | 8–10 years | 4.1/5 |
5 Best Small Boilers Reviewed By Our Experts
The best small boilers each squeeze strong performance into a genuinely reduced case size, so it’s worth understanding exactly what makes each one stand out. Here’s our detailed breakdown of each model.
1. Worcester Bosch Greenstar CDi Compact: Best For Smallest Overall Case Size
The Worcester Bosch Greenstar CDi Compact holds the title of one of the smallest combi boilers ever produced by a major UK brand, measuring just 690mm tall, 390mm wide, and 280mm deep, small enough to disappear into most standard kitchen cupboards.
Worcester Bosch built this specific model to address a genuine gap in the market for flats and smaller properties where a full sized combi boiler simply wouldn’t fit. Despite the reduced dimensions, it retains the same dependable engineering and nationwide installer support the brand is known for.
| Feature | Detail |
| Dimensions | 690 x 390 x 280mm |
| Available outputs | 25kW, 30kW |
| Efficiency | A-rated, 94% |
| Warranty | 7–10 years |
| Boiler price | £900–£1,200 |
| Installed price | £2,000–£2,600 |
Specs and features: The unit includes a compact case design, an easy to read display, and full compatibility with Worcester’s own smart thermostat range despite its smaller overall footprint.
Efficiency: It carries an ErP A rating with a 94% efficiency score, matching the performance of Worcester’s larger combi boilers despite the reduced case size.
Estimated cost of the unit: The boiler alone typically costs between £900 and £1,200 depending on output size and supplier.
Cost with installation: Once fitted, most households pay between £2,000 and £2,600, similar to a standard sized Worcester combi given the same underlying components.
Running costs: Running costs stay competitive thanks to the strong efficiency rating, matching what you’d expect from a full sized Worcester Bosch combi boiler of the same output.
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 CDi Compact?
Choose the Worcester Bosch Greenstar CDi Compact if…
- You have an unusually tight kitchen cupboard or utility space
- You want a well known, trusted brand backed by a huge installer network
- Your home has one bathroom with moderate hot water demand
- You value strong aftercare and nationwide spare parts availability
Do not choose the Worcester Bosch Greenstar CDi Compact if…
- Your household has heavy simultaneous hot water demand across multiple bathrooms
- You want the longest possible warranty without an extension
- Space isn’t actually a limiting factor at your property
2. Viessmann Vitodens 050-W: Best Selling Compact Boiler
The Viessmann Vitodens 050-W has become one of the best selling boilers in the entire UK market, not just within the compact category, thanks to its blend of genuinely efficient German engineering and a surprisingly competitive price point.
Viessmann built this model to compete directly with entry level offerings from bigger UK brand names while still packing in the stainless steel heat exchanger technology the manufacturer is known for. It’s a particularly strong choice for homeowners who want compact dimensions without sacrificing long term durability.
| Feature | Detail |
| Dimensions | 700 x 400 x 350mm |
| Available outputs | 25kW, 30kW, 35kW |
| Efficiency | A-rated, 94% |
| Warranty | 10 years |
| Boiler price | £790–£1,190 |
| Installed price | £1,900–£2,500 |
Specs and features: The boiler includes a backlit display, a stainless steel heat exchanger for corrosion resistance, and a case size that fits comfortably into most standard installation spaces.
Efficiency: It carries an A-rated efficiency of 94%, matching the premium end of the market despite sitting at a genuinely accessible price point.
Estimated cost of the unit: Pricing for the boiler alone generally sits between £790 and £1,190, depending on output size.
Cost with installation: Installed costs typically range from £1,900 to £2,500, among the most competitively priced options for a stainless steel heat exchanger boiler.
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 aluminium components.
Which? and Trustpilot ratings: Viessmann holds Which? Recommended Provider status and an excellent 4.6 out of 5 on Trustpilot, with customers regularly highlighting value for money and long term reliability as standout points.
Should You Choose The Viessmann Vitodens 050-W?
Choose the Viessmann Vitodens 050-W if…
- You want a stainless steel heat exchanger at an accessible price point
- You plan to keep your boiler for well over a decade
- You value genuinely strong efficiency without paying a premium
- Your installation space is tight but not the absolute smallest available
Do not choose the Viessmann Vitodens 050-W if…
- You need the single smallest case size on the market
- You want the biggest, most recognised UK household brand name
- You’re prioritising the very lowest unit price above all else
3. Intergas Compact ECO RF: Best For Simplicity And Fewer Moving Parts
The Intergas Compact ECO RF stands out among small boilers because of its genuinely unusual design philosophy, using a single heat exchanger for both central heating and hot water rather than the two separate exchangers found in most rival boilers.
Intergas has built a strong reputation among installers specifically because this simpler internal design means fewer components that can potentially fail over the boiler’s working life. It’s a smart pick for homeowners who value mechanical simplicity alongside a compact footprint.
| Feature | Detail |
| Dimensions | 700 x 410 x 350mm |
| Available outputs | 24kW, 30kW |
| Efficiency | A-rated, 93% |
| Warranty | 10 years |
| Boiler price | £850–£1,150 |
| Installed price | £1,900–£2,500 |
Specs and features: The boiler includes a single heat exchanger design, a straightforward digital display, and a compact case that installers consistently describe as quick and easy to fit.
Efficiency: It carries an A-rated efficiency of around 93%, a genuinely solid figure that reflects the benefits of its simplified internal design.
Estimated cost of the unit: The boiler alone typically costs between £850 and £1,150.
Cost with installation: Installed pricing generally runs from £1,900 to £2,500.
Running costs: Running costs sit broadly in line with other A-rated compact boilers, with the simplified design potentially reducing long term servicing costs due to fewer components requiring maintenance.
Which? and Trustpilot ratings: Intergas has not featured as prominently in UK Which? surveys as some larger brands, but it holds a respectable 4.3 out of 5 on Trustpilot, with reviewers often praising the boiler’s straightforward reliability.
Should You Choose The Intergas Compact ECO RF?
Choose the Intergas Compact ECO RF if…
- You value a simplified internal design with fewer potential points of failure
- You want a genuinely reliable, low maintenance small boiler
- Your installation space benefits from a straightforward, easy to fit unit
- You’re comfortable with a less mainstream UK brand name
Do not choose the Intergas Compact ECO RF if…
- Brand recognition and market share matter to you
- You want the widest possible network of specialist installers
- You need the absolute highest efficiency figure on this list
4. Ideal Logic Plus: Best Value Compact Boiler
The Ideal Logic Plus has earned a strong reputation as the compact 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 smaller rental flats who need dependable heating without overspending.
| Feature | Detail |
| Dimensions | 700 x 395 x 280mm |
| Available outputs | 24kW, 30kW |
| Efficiency | A-rated, 91% |
| Warranty | 10–12 years |
| Boiler price | £700–£950 |
| Installed price | £1,700–£2,300 |
Specs and features: The boiler includes a backlit display, a fully modulating pump, and a case size that fits comfortably into most standard kitchen or utility cupboards.
Efficiency: It carries an A-rated efficiency of around 91%, 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 £1,700 to £2,300, 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 smaller 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 Logic Plus?
Choose the Ideal Logic Plus if…
- You want strong performance without paying premium brand prices
- You’re a landlord managing a smaller rental flat on a budget
- You need a compact fit for a smaller kitchen cupboard
- You value a long warranty at a lower price point
Do not choose the Ideal Logic Plus if…
- You want the absolute highest efficiency figure available
- You’re set on a premium European engineering brand
- Your household has particularly heavy hot water demand
5. Glow-worm Compact: Best Budget Friendly Small Footprint
The Glow-worm Compact rounds out this list as a genuinely affordable option for homeowners and landlords who need a small footprint boiler without stretching their budget too far.
Glow-worm has manufactured boilers in the UK for decades and is part of the same manufacturing group as Vaillant, which means it benefits from some shared engineering knowledge despite sitting at a noticeably lower price point. It’s a sensible choice for smaller properties where budget is the primary consideration alongside limited installation space.
| Feature | Detail |
| Dimensions | 710 x 390 x 279mm |
| Available outputs | 25kW, 30kW |
| Efficiency | A-rated, 92% |
| Warranty | 8–10 years |
| Boiler price | £650–£900 |
| Installed price | £1,700–£2,200 |
Specs and features: The boiler includes a simple, easy to use control panel, a compact case suited to tight cupboard installations, and reliable modulation across its available output range.
Efficiency: It carries an A-rated efficiency of around 92%, a solid figure that keeps it competitive against pricier alternatives despite the lower unit cost.
Estimated cost of the unit: The boiler alone typically costs between £650 and £900, among the most affordable options at this case size.
Cost with installation: Installed pricing generally runs from £1,700 to £2,200, making it one of the cheapest options overall on this list.
Running costs: Running costs are broadly comparable to the Ideal Logic Plus given the similar efficiency band, making it a sensible option for smaller households watching their energy spend closely.
Which? and Trustpilot ratings: Glow-worm has not featured prominently in recent Which? surveys, but it holds a reasonable 4.1 out of 5 on Trustpilot, with reviewers often mentioning good value for money as a key strength.
Should You Choose The Glow-worm Compact?
Choose the Glow-worm Compact if…
- You want the lowest unit and installed price among genuinely compact boilers
- Your installation space is tight but budget is your top priority
- You’re comfortable with a shorter warranty than some premium rivals
- You don’t need the very latest smart features
Do not choose the Glow-worm Compact if…
- You want the longest possible warranty on this list
- Brand recognition matters to you for future resale value
- Your household has heavier hot water demand than a typical small property
How We Choose The Best Small Boilers
We chose the best small boilers by combining hands-on installation experience gathered from fitting boilers into flats, small kitchens, and tight utility spaces right across the UK with independent data from trusted third party sources. As nationwide installers working with homeowners and landlords every single day, our recommendations reflect what genuinely fits and performs well in real tight spaces, not just impressive sounding spec sheets.
- Verified manufacturer dimensions, efficiency, and warranty terms directly against official documentation from Worcester Bosch, Viessmann, Intergas, Ideal, and Glow-worm
- Cross referenced independent customer feedback from Trustpilot to balance technical performance against genuine satisfaction with compact installations
- Drew on feedback from our own Gas Safe registered installer team, who regularly fit these exact models into flats and properties with limited cupboard space
- Compared unit and installed pricing across multiple UK suppliers to ensure figures reflect genuine market conditions rather than inflated list prices
- Prioritised boilers that maintain strong efficiency and flow rate despite their reduced case size, since a smaller boiler shouldn’t mean weaker performance
- Considered the needs of both homeowners and landlords, including smaller rental flats where installation space is often the single biggest constraint
How To Choose The Best Small Boiler For Your Property
Choosing the best small boiler for your property comes down to confirming your exact available space and matching it to a genuinely suitable output rather than assuming any compact boiler will simply fit. Work through this checklist before making your final decision.
- Measure your available installation space precisely, including height, width, and depth, since even a few millimetres can rule out certain models in a genuinely tight cupboard
- Confirm the boiler’s output still suits your property despite its smaller case, since a compact design shouldn’t mean sacrificing enough heating and hot water capacity
- Check the flow rate carefully, since some smaller boilers have a slightly reduced flow rate compared to full sized equivalents, which matters more in homes with two bathrooms
- Consider whether your property genuinely needs a compact model, since standard sized boilers often cost less for the same performance if space isn’t actually restricted
- Compare warranty terms across compact models, since some manufacturers offer shorter warranties on entry level compact ranges compared to their flagship full sized boilers
- Factor in your total budget for both the unit itself and installation, remembering that compact boilers don’t always cost less than standard sized equivalents
- Ask about smart thermostat compatibility if you want to manage your heating remotely even in a smaller property
- Get a proper home survey before committing, since an installer can confirm the exact model that will fit your specific cupboard or utility space with room to service it properly
Ready to Upgrade to a Compact Boiler?
If you’re replacing an old boiler or need a model that fits neatly into a kitchen cupboard or utility space, choosing the right compact boiler is only half the job. A professional installation ensures your new boiler is correctly sized, installed safely, and performs efficiently for years to come.
At Eazy Heat, we install compact boilers from leading manufacturers, including Worcester Bosch, Viessmann, Ideal, Intergas, and Glow-worm, for homeowners and landlords across the UK. Every installation is carried out by experienced Gas Safe engineers and includes a market-leading 12-year parts and labour warranty for complete peace of mind.
Our simple online quotation tool makes replacing your boiler quick and hassle-free. In just a few steps, you’ll receive a fixed-price quote with no hidden fees or obligation to proceed. If you’re happy with the price, we’ll arrange a professional installation, with next-day fitting often available.
Get your free online boiler installation quote today and find out how affordable a new compact boiler could be for your home.
FAQs
Can a small boiler be installed in a bedroom cupboard rather than a kitchen?
Small boilers can generally be installed in a bedroom cupboard provided there’s adequate ventilation and the space meets building regulations for boiler clearance, though most installers recommend checking with a Gas Safe engineer first since bedroom installations sometimes require additional safety considerations around flue positioning. Utility cupboards and kitchen spaces remain the most common choice simply because they typically already have suitable pipework nearby.
Do small boilers cost more to service than standard sized models?
Small boilers generally cost the same to service as standard sized equivalents from the same manufacturer, since the internal components and required annual checks remain largely similar despite the reduced case size. Servicing costs are typically influenced more by boiler brand and complexity than by the physical dimensions of the unit itself.
Is it possible to hide a small boiler behind a cupboard door for aesthetic reasons?
Many small boilers can be concealed behind a standard cupboard door, provided there’s enough clearance for ventilation and the door doesn’t restrict access needed for annual servicing or potential repairs. It’s worth discussing any planned concealment with your installer beforehand to ensure it meets manufacturer guidelines and doesn’t void the warranty.
Can a small boiler still support future additions like a conservatory or extension?
A correctly sized small boiler can often still support a future conservatory or small extension, provided the additional radiators fall within the boiler’s existing spare capacity, though larger extensions may require an output upgrade. It’s sensible to mention any planned future building work to your installer at the point of choosing a boiler size, even if the compact model you want has a slightly reduced margin for expansion.
Are small boilers noisier than standard sized boilers due to their compact components?
Small boilers are not inherently noisier than standard sized models, since noise levels depend more on the quality of internal components like the fan and pump rather than the overall case size. Premium brands with stainless steel heat exchangers and well engineered fans, such as Viessmann, tend to run quietly regardless of their compact dimensions.
