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Combi Boilers

What is a combination boiler?

A combination or ‘combi’ boiler is both a high efficiency water heater and a central heating boiler in a single compact unit. Combi boilers heat water directly from the mains when you turn on a tap, so you won’t need a hot water storage cylinder or a cold water storage tank.

Compact, cost-effective and energy-efficient, combi boilers well suited for smaller homes with a modest hot water demand, find out if a combi is the perfect paring for your home by taking our quick quiz below - your new boiler is just a click away.

Worcester Bosch Cdi compact combi boiler
Ideal Logic+ Combi boiler
Worcester Bosch Greenstar 8000 Life combi boiler
Ideal Logic+ Heat Only boiler
Glow - Worm Energy Regular Boiler
Ideal Logic+ System boiler
Alpha E-Tec System boiler
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An illustrated infographic of the way a combi boiler works. Step one shows a house with a combi boiler in the bottom floor and says "A combi pulls water directly from the mains supply". Step two shows the combi boiler up close with the caption "Cold water flows in and hot water flows out of the boiler". Step three shows a radiator with the caption "Water flows through a diverter valve to either heating circuits or taps". Step four shows a bath with a shower illustration with the caption "Instant hot water from your boiler to your taps and shower"
The ins and outs of your new boiler

How does a combi boiler work?

A combi boiler directly heats water from the mains when you turn on a tap or your heating. It uses a flow switch to sense the demand and ignite a gas burner. This burner heats a component called a heat exchanger, which transfers its heat to the water flowing through it.

If you're running a tap, the boiler prioritizes heating that water. If your heating is on, a part called a diverter valve directs the heat towards the water for your radiators.

What sets combi boilers apart is their ability to provide heating and hot water on-demand, rather than storing hot water. This makes them more energy-efficient, providing heat when and where you need it, and saving you money.

Heating and hot water waiting for you

What are the benefits of choosing a combi boiler?

Combi's are efficient

They heat on demand which can result in huge savings for households that are use to a boiler that hears litres of water on standby that doesn’t always get used

Compact in size

Combi boilers are small in size and easy to hide, along side eliminating the need for hot water tanks, cylinders and heat pumps.

Flexible install location

Combis don’t require a storage tank or water cylinder – with it being a single unit that is relatively small there is more flexibility on where you can have it installed.

Choose the best for your home

Why are so many people switching to a combi?

Combi boilers are the straightforward choice for homeowners as they don't require the extra components and mechanisms that heat only and system boilers need to function. Choosing a combi for your home means there’s no need for water tanks/ immersion heaters or heat pumps.

They’re compact in size, providing on demand hot water and heating to households directly through mains water supply, ensuring economical and energy efficiency as you're only using your heating and hot water when you need it.

What you need to know

The straight forward Combi boiler installation process



Our engineers will carry out a full assessment of your heating and hot water requirements, as well as the existing plumbing and electrical systems in your home



We'll take care of the disposal of the old boiler and any associated parts, if an existing system is being replaced



We'll connect your brand new combi boiler, this includes connecting it to the gas, water, and electrical supply



Our engineers will make sure the new boiler is working as it should, this includes flushing and cleaning the heating system, pressure testing and setting up the controls


Final Checks

Over to you, our experts will demonstrate how to use the new boiler and a review of the install and operating instructions


Clean Up

Your installation is now complete, but our experts won't leave until any mess is cleared

12 year exclusive warranty period with Padly boiler installs

Logic Vogue Max boiler with a 12-year exclusive warranty period with Padly
What size do you need?

What size combi will I need for my home?

When considering boiler ‘size’ it's best to not think literally. The size of your boiler will typically refer to a boilers output/power, not the physical dimensions of the boiler. A combi boilers power is measured in Kilowatts – therefore the higher the kW, the more powerful the boiler will be to meet your properties hot water and heating requirements. For example, if you live in a small home with one bathroom, then a low-power (small) combi is best recommended. The hot water output largely depends on the cold-water flow rate to your property, therefore, we will test the flow rate with you when we survey and recommend the perfect size boiler for your property with the cold water flow rate in mind.

Regular (Heat-only) Boiler

6 Radiators
12 kW
8 Radiators
15 kW
12 Radiators
21 kW
15 Radiators
26 kW
20 Radiators
33 kW

Combination Boiler

1-2 bedrooms, 10 radiators, 1 bathroom
24 kW - 27 kW
2-3 bedrooms, 15 radiators, 1 bathroom
28 kW - 34 kW
4+ bedrooms, 28 radiators, 2 bathrooms
35 kW - 42 kW

System Boiler

1 -3 bedrooms, 1 bathroom
12 kW - 15 kW
3 - 4 bedrooms, 1 - 2 bathrooms
18 kW - 24 kW
4+ bedrooms, 2+ bathrooms
30 kW +

Get your fixed quote on industry-leaders like Worcester Bosch

Worcester Bosch boilers with their Which? approved awards
Get installed from tomorrow

Boiler installation in 3 easy steps

Step 1

Select your brand new boiler and fill out our online quote form, whether you're looking for a compact combi boiler or powerful system - we've got a range to suit all your homes needs.

Step 2

We’ll be in touch for a thorough survey of your property either remotely or on site, after which our experts will be in touch with a quote for installation.

Step 3

Choose a payment/ finance option and we'll book in a date for your engineer to install your brand-new boiler, remove the old boiler and show you how everything works.

Your questions, answered

Have any further questions? Get in touch with one of our experts to discuss your options!

What are the benefits of choosing a combi boiler for my home?

Combi boilers offer several key benefits, they're compact and don't require a separate hot water tank, making them a great choice for smaller homes or flats. Secondly, combi boilers provide hot water on demand by heating it directly from the mains when you turn on a tap, providing excellent efficiency and eliminating the need to wait for the water to heat up. Lastly, because they are common, finding parts and servicing can be easier and potentially cheaper than for other types of boilers.

How does the cost of a combi boiler installation compare to other boiler types?

While costs can vary widely based on the specific boiler model and the complexity of the installation, combi boilers can often be less expensive to install than systems or conventional boilers. This is mainly because combi boilers have simpler setups, without the need for a separate water tank or cylinder.

Can a combi boiler save me money on my energy bills?

Yes, combi boilers can potentially save you money on your energy bills because of their high efficiency. They only heat water when it's needed, meaning you're not paying to heat a whole tank of water that might go unused. However, the actual savings will depend on several factors, including your home's insulation and your household's hot water usage.