Combi Boiler Guide: Prices, Sizes, Types and and Leading Brands

When it comes to the cost of a new combi boiler, prices vary greatly according to the brand, output and warranty. The average cost of a combi boiler ranges from £455 to over £2,650, but you’ll need to pay an extra £600 to £1,500 to get the boiler installed. Combine these figures, and you’re looking at spending anything from £1,055 to £4,150 for a new combi and the installation.

Before choosing a combi boiler for your home, you need to know what size (kW output) and type of combi boiler you require. You must also consider your budget, which is why it’s so important to compare combi boiler prices and familiarise yourself with each of the available boiler brands.

To help you make the right decision, we’ve put together a guide that explains what a combi boiler is, how to select the right size for your home and the different fuel types that the boiler run on. Our useful guide also lets you compare combi boiler prices and the pros and cons of installing a new combination boiler.

What is Combi Boiler?

A combi (or combination) boiler provides not only heat for your radiators but also instant hot water for your taps. As all combi boilers heat water directly from the mains and do not require a separate hot water storage cylinder in the airing cupboard or cold water storage tank in the loft, they are perfect for flats and smaller properties with limited indoor space. Due to their ability to heat water instantly on demand, combi boilers are also more economical and energy-efficient.

The Right Size Combi Boiler For Your Home

Choosing a new combi boiler can be overwhelming, with so many options available in the UK today. Although it’s impossible to tell you which size combi you will need without assessing your property and usage habits, we have put together a rough guide below to help find the right size boiler.   

Please note: This information must be used as a rough guide only and won’t be accurate for every property. We suggest you always consult a Gas Safe engineer to give you advice on the best boiler type, model and size for your home.

Combi Boiler Types

Most people opt for gas combi boilers as they tend to be cheaper to run, however, there are other options to consider before making any decisions. Let’s take a look at the different types of combi boilers from which you can choose.

Gas Combi Boilers

As previously mentioned, natural gas combi boilers are the most common option for properties connected to the mains gas supply because it costs less to heat a home with gas than with oil or electric.

Oil Combi Boilers

If you are off the gas grid, you may want an oil-fired combi boiler. You will need a separate tank (outside) to store the oil, which is delivered to your home by an oil supplier. This means you must keep an eye on how much oil you are using to make sure you never run out before your next delivery is due.

LPG Combi Boilers

LPG (which stands for liquefied petroleum gas) combi boilers are similar to oil boilers in that the fuel needs to be delivered by a supplier and then stored in an outdoor tank. Again, like oil boilers, they burn fuel to produce the energy that provides you with hot water for your taps and radiators. You may be interested to know that some natural gas combi boilers can be converted to LPG boilers with special conversion kits.

Electric Combi Boilers

Another option if do not have access to mains gas is electric combi boilers, which use electricity to heat water rather than gas. One of the biggest selling points of these boilers is that they can be up to 99% efficient. These boilers are also compact and allow for greater siting flexibility because they do not require a flue. The downside is that running costs may be higher as electricity is more expensive than gas.

Combi Boiler Advantages and Disadvantages

Even though combi boilers have many advantages and are common in homes across the UK, they may not be right for every property. It is therefore essential that you seek advice from a Gas Safe registered engineer before purchasing a new boiler, regardless of type.

Advantages

Compact size: The majority of combi boilers are extremely compact and can be installed almost anywhere in the home. Some are even small enough to fit inside a standard-sized kitchen cupboard. Plus, you won’t need a cold water tank or hot water cylinder with a combi, which means more free space in your loft and airing cupboard.

Hot water on demand: Combi boilers are designed to provide hot water (and central heating) on demand from one single unit, so you don’t need to wait for the water to heat up whenever you decide to have a bath or shower. Also, combi boilers are more cost-effective because they only heat the water you use.

Shorter installation time: With less pipework and no extra tanks to deal with, combi boilers are relatively easy to install. This means you can expect a quicker and neater installation, which helps to keep fitting costs to a minimum as well.

You save money: As water is heated instantly (rather than being heated and then stored in a separate cylinder), combi boilers are more energy efficient and have a smaller carbon footprint when compared to conventional boilers. New combi boilers are also condensing boilers, meaning they save energy by reusing heat that would otherwise be wasted. By being so efficient, combi boilers can help to lower your energy bills.

Disadvantages

Not great for homes with multiple bathrooms: Combi boilers are best suited to smaller properties and households with lower hot water demands. Remember, they do not work alongside a tank or cylinder, so they may struggle to cope with two baths or showers running at the same time. Because of this, combi boilers are generally not recommended for homes with more than one bathroom.

No backup immersion heater: In the event of a breakdown, you may be left without any hot water as combi boilers are not fitted with immersion heaters. You can, of course, call out an engineer but there is no guarantee that they will be able to come to your home and fix the problem right away.

Combi Boiler Prices By the Leading Brands

Many brands, such as Worcester Bosch, Viessmann and Ideal manufacture combi boilers, which vary in size and cost depending on the model. There are lots of options to choose between including budget, mid-range and high-end models. Obviously, the larger and more sophisticated the combi boiler, the more you will need to pay.

Below are some comparison tables that enable you to compare combi boiler prices and models from different boiler brands to give you a better idea of prices. The prices listed include VAT but exclude the cost of installation.

Worcester Bosch

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
Greenstar 28 CDi Compact Combi	H - 680 mm W - 390 mm D - 280 mm	28 kw	11.4 l/min		£ 1,105.04
Greenstar 30 Si Compact Combi	H - 690 mm W - 390 mm D - 280 mm	30 kw	12.3 l/min		£ 1,142.46
Greenstar 24i Junior Combi	H - 710 mm W - 400 mm D - 300 mm	24 kw	9.8 l/min		£ 1,169.99
Greenstar 38 CDi Classic Combi	H - 760 mm W - 440 mm D - 360 mm	38 kw	16.4 l/min		£ 1,427.92
Greenstar 38 CDi Classic Combi	H - 850 mm W - 600 mm D - 600 mm	29 kw	20.1 l/min		£ 2,053.68
Greenstar Heatslave II 32	H - 855 mm W - 520 mm D - 600 mm	32 kw	22 l/min		£ 2,520.00
Greenstar Heatslave II 25 External	H - 950 mm W - 640 mm D - 770 mm	25 kw	18 l/min		£ 2,572.82

Ideal

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
Independent C24 Combi	H - 700 mm W - 395 mm D - 278 mm	24 kw	9.9 l/min		£ 625.36
Logic Combi 24	H - 700 mm W - 395 mm D - 278 mm	24 kw	9.9 l/min		£ 718.38
Logic + Combi 35	H - 700 mm W - 395 mm D - 278 mm	35 kw	14.5 l/min		£ 914.75
Vogue Combi 26	H - 740 mm W - 445 mm D - 330 mm	26 kw	10.6 l/min		£ 980.00
Logic Max Combi 35	H - 700 mm W - 395 mm D - 278 mm	35 kw	14.5 l/min		£ 1,077.43
Vogue Max Combi 40	H - 700 mm W - 395 mm D - 278 mm	40 kw	16.4 l/min		£ 1,339.20

Biasi

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
Riva Plus Combi ERP 24	H - 803 mm W - 400 mm D - 350 mm	24 kw	11.6 l/min		£ 454.80
Advance Plus Combi ERP 30	H - 700 mm W - 400 mm D - 290 mm	30 kw	16.2 l/min		£ 598.90
Inovia Combi ERP 30	H - 700 mm W - 400 mm D - 290 mm	30 kw	16.2 l/min		£ 660.00
Advance Combi 35	H - 700 mm W - 400 mm D - 290 mm	35 kw	13.3 l/min		£ 673.50

Vokera

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
Compact A 29	H - 715 mm W - 405 mm D - 248 mm	29 kw	11.9 l/min		£ 485.00
Vision Combi 30	H - 715 mm W - 405 mm D - 248 mm	30 kw	12 l/min		£ 590.00
Evolve Combi 28	H - 750 mm W - 420 mm D - 275 mm	28 kw	12.3 l/min		£ 775.00
Unica i Combi 36	H - 780 mm W - 400 mm D - 358 mm	36 kw	14.7 l/min		£ 885.00
Linea 1 Combi 38	H - 845 mm W - 453 mm D - 358 mm	38 kw	15.6 l/min		£ 1,069.99

Keston

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
Keston Combi 35	H - 700 mm W - 395 mm D - 278 mm	35 kw	14.5 l/min		£ 1,303.70

Ferroli

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
Ferroli i29 Combi	H - 680 mm W - 400 mm D - 330 mm	29 kw	15.6 l/min		£ 429.00
Modena 32C HE Combi	H - 600 mm W - 400 mm D - 320 mm	32 kw	13.1 l/min		£ 646.16

Viessmann

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
Vitodens 050-W 35 Combi	H - 707 mm W - 400 mm D - 350 mm	35 kw	14 l/min		£ 874.80
Vitodens 100-W 26 Combi	H - 700 mm W - 400 mm D - 350 mm	26 kw	10.6 l/min		£ 1,114.88
Vitodens 200-W 30 Combi	H - 850 mm W - 450 mm D - 360 mm	30 kw	14.3 l/min		£ 1,594.34
Vitodens 111-W 35 Storage Combi	H - 900 mm W - 600 mm D - 480 mm	35 kw	18 l/min		£ 1,735.78
Vitodens 222-F 26 Combi	H - 1425 mm W - 600 mm D - 595 mm	26 kw	23 l/min		£ 2,686.85

Vaillant

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
ecoFIT Pure Combi 25	H - 700 mm W - 390 mm D - 295 mm	25 kw	10.4 l/min		£ 858.00
ecoTEC Pro Combi 28	H - 720 mm W - 440 mm D - 338 mm	28 kw	11.1 l/min		£ 925.00
ecoTEC Plus Combi 32	H - 720 mm W - 440 mm D - 338 mm	32 kw	13 l/min		£ 1,185.65
ecoTEC Exclusive Combi 43	H - 720 mm W - 440 mm D - 474 mm	43 kw	17.8 l/min		£ 1,916.88

Baxi

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
100 Combi LPG 24	H - 700 mm W - 395 mm D - 300 mm	24 kw	9.8 l/min		£ 608.40
400 Combi 24	H - 700 mm W - 395 mm D - 279 mm	24 kw	9.8 l/min		£ 689.44
200 Combi 28	H - 700 mm W - 395 mm D - 279 mm	28 kw	11.5 l/min		£ 698.00
100 Combi 28	H - 700 mm W - 290 mm D - 300 mm	28 kw	11.5 l/min		£ 728.40
400 Combi LPG 28	H - 700 mm W - 395 mm D - 279 mm	28 kw	11.5 l/min		£ 729.41
600 Combi 30	H - 700 mm W - 390 mm D - 285 mm	30 kw	12.2 l/min		£ 808.61
Duo-tec Combi 33	H - 780 mm W - 450 mm D - 345 mm	33 kw	13.5 l/min		£ 918.04
EcoBlue + Combi 33	H - 700 mm W - 390 mm D - 295 mm	33 kw	13.5 l/min		£ 995.76
Platinum Combi 40	H - 780 mm W - 450 mm D - 345 mm	40 kw	16.4 l/min		£ 1,126.67
EcoBlue Advance Combi 40	H - 763 mm W - 450 mm D - 345 mm	40 kw	16.4 l/min		£ 1,228.72

Potterton

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
Gold Combi 28	H - 780 mm W - 450 mm D - 345 mm	28 kw	11.5 l/min		£ 696.28
Titanium Combi 24	H - 780 mm W - 450 mm D - 345 mm	24 kw	9.8 l/min		£ 767.52
Assure Combi 25	H - 700 mm W - 290 mm D - 345 mm	25 kw	10.2 l/min		£ 834.00
Promax Combi 28	H - 780 mm W - 450 mm D - 345 mm	28 kw	11.5 l/min		£ 968.33
Promax Ultra Combi 40	H - 763 mm W - 450 mm D - 355 mm	40 kw	16.4 l/min		£ 1,309.80

Glow-Worm

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
Easicom3 Combi 24	H - 740 mm W - 418 mm D - 300 mm	24 kw	9.8 l/min		£ 580.00
Betacom3 Combi 30	H - 740 mm W - 418 mm D - 300 mm	30 kw	9.8 l/min		£ 610.00
Essential Combi 28	H - 740 mm W - 418 mm D - 300 mm	28 kw	11.5 l/min		£ 658.00
Ultimate3 Combi 35	H - 740 mm W - 418 mm D - 300 mm	35 kw	11.5 l/min		£ 774.00
Energy Combi 35	H - 700 mm W - 390 mm D - 280 mm	35 kw	11.5 l/min		£ 912.24
Energy Store Combi 35	H - 890 mm W - 470 mm D - 561 mm	35 kw	12.2 l/min		£ 1,547.64

Alpha

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
Evoke Combi 28	H - 712 mm W - 440 mm D - 255 mm	28 kw	12.1 l/min		£ 625.00
E Tec Combi 33	H - 712 mm W - 440 mm D - 255 mm	33 kw	14.1 l/min		£ 729.00
E Tec Plus Combi 28	H - 712 mm W - 440 mm D - 268 mm	28 kw	12.1 l/min		£ 838.13
Intec GS Combi 40	H - 1000 mm W - 440 mm D - 360 mm	40 kw	15.8 l/min		£ 1,795.00

Ariston

MODEL	DIMENSIONS	OUTPUT	MAX FLOW RAT	EFFICIENCY	TYPICAL PRICE
Clas HE 30 Evo Combi	H - 810 mm W - 490 mm D - 420 mm	30 kw	12.9 l/min		£ 659.00
Clas Net One 38 Combi	H - 745 mm W - 400 mm D - 385 mm	38 kw	15.5 l/min		£ 1,140.00

Don’t forget: Prior to making any decisions, you must ask a Gas Safe engineer to help you determine which combi boiler model and output is right for your home.