Best Compact Combi Boilers For Small Homes

If you need a new combi boiler to fit inside a small space such as a kitchen cupboard, a shallow utility room or a compact airing cupboard, choosing a physically smaller model is essential.

Compact combi boilers are designed with shorter height and reduced depth, making installation easier while still delivering reliable heating and hot water.

This guide focuses only on compact sized combi boilers that work well in small and medium homes.

It does not compare boilers in a broad sense and it does not attempt to rank the best boilers overall.

Each model listed is widely recognised by engineers for reliability, cupboard fit and consistent performance.

Best compact small combi boilers

Combi boilers already save space by removing the need for water tanks, but some models are designed specifically to fit within standard 300 mm deep wall cupboards.

These are ideal for flats, small houses and properties where space is limited.

If you want to compare these cupboard fit options with the wider market, see our guide to the best combi boilers.

Quick comparison table

Worcester Bosch Greenstar CDi Compact

Dimensions
H 680 mm, W 390 mm, D 280 mm

The Worcester Bosch Greenstar CDi Compact lives up to its name.

It is purpose built to fit inside a standard kitchen cupboard and is one of the smallest gas combi boilers available from Worcester Bosch.

Despite the reduced size, it offers strong heating and hot water performance and remains a popular choice among engineers.

Output sizes and suitability

Efficiency

The CDi Compact is ErP A rated at around 91 percent efficiency, suitable for small homes wanting a cupboard fit without sacrificing performance.

Ideal Logic Plus Combi

Dimensions
H 700 mm, W 395 mm, D 279 mm

The Ideal Logic Plus is a reliable compact boiler commonly found in flats, small houses and properties where installation space is tight.

It fits neatly inside a kitchen cupboard and has received strong consumer feedback and awards for ease of use and dependable performance.

Output sizes and suitability

Efficiency

The Logic Plus range is around 90 percent efficient and offers good value for small homes.

Viessmann Vitodens 100 W

Dimensions
H 700 mm, W 400 mm, D 350 mm

The Vitodens 100 W is known for its high build quality, quiet operation and stainless steel heat exchanger.

It remains one of the most engineer recommended boilers for compact installations due to long term reliability.

Output sizes and suitability

Efficiency

Up to 94 percent efficiency places the Vitodens 100 W among the most efficient compact boilers in this category.

Viessmann Vitodens 050 W

Dimensions
H 707 mm, W 400 mm, D 350 mm

The Vitodens 050 W is the smaller and more affordable compact option from Viessmann.

It is highly reliable, quiet in operation and designed for both modernisations and new build homes.

Its shallower depth compared with the 100 W version is helpful for tighter cupboard spaces.

Output sizes and suitability

Efficiency

Around 94 percent efficiency and an A rating make this a strong choice for households wanting compact dimensions and affordable running costs.

Alpha E Tec

Dimensions
H 712 mm, W 440 mm, D 275 mm

The Alpha E Tec is the most compact boiler in the Alpha range.

It is designed to fit inside standard kitchen cabinets and offers good performance at an accessible price point.

It remains a popular option among landlords and homeowners who want a cost effective small boiler.

Output sizes and suitability

Efficiency

The Alpha E Tec operates at around 89 percent efficiency, providing good performance for small properties on a budget.

iHeat boiler installation support

If you are unsure which compact boiler fits your home, iHeat can help.

Our team installs combi boilers from leading manufacturers including Worcester Bosch, Viessmann, Ideal and Alpha, and we offer fixed online quotes, next day installation availability in many areas and full support from our Gas Safe engineers.