Converting to a combi boiler

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If you're considering a switch to a combi boiler or simply just want to learn more about this efficient heating solution, this guide has you covered! Explore everything you need to know about converting to a combi boiler in this comprehensive Padly guide.

In this guide, our experts explore the fundamentals of combi boilers, the benefits they offer, a step-by-step Padly installation process, and some popular FAQs you may have surrounding the topic of converting to a combi boiler.

Combi boiler fundamentals

Before our experts dive into the ins and outs of converting to a combi boiler, it's essential that first, you understand what a combi boiler is and how it works.

What is a combi boiler?

A combination or 'combi' boiler, is a type of heating system that combines both hot water and central heating in a single unit. Unlike traditional systems that have separate hot water tanks or cylinders, a combi boiler heats water on-demand as you need it. This compact design eliminates the need for extra storage space, making it a popular choice for homes with limited room.

How does a combi boiler work?

Combi boilers operate on a straightforward principle. They directly heat 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 prioritises 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 as and when you need it, which reduces energy wastage compared to traditional systems and in turn, saves you money.

Benefits of changing to a combi boiler

Combi boilers have a number of advantages that you and your home could benefit from:

Space-saving design

Combi boilers are compact and don't require a separate hot water tank, therefore freeing up valuable space in your home.

Energy efficient

Combi boilers are highly efficient because they only heat water when it's needed. This can lead to lower energy bills and reduced carbon emissions.

Instantaneous hot water

With a combi boiler, you get hot water instantly which eliminates the need to wait for a tank to heat up.

Cost savings

A combi boiler can offer you significant long-term savings as you will only be paying for the hot water you require, rather than having to pay to heat a whole cylinder of water that you might not need or use all of.


When properly maintained, combi boilers are well-known for their reliability and longevity.

Step-by-step process

If you think that changing to a combi boiler is right for you, it is important you know what to expect on installation day. Below, our experts have shared Padly's straightforward boiler installation process:

1. Assessment

Our engineers will carry out a full assessment of your heating and hot water requirements, as well as the existing plumbing systems in your home. We will also assess the electrical requirements for your new boiler.

2. Removal

If an existing system is being replaced, we'll take care of the disposal of the old boiler and any associated parts. This includes removing your existing cylinder and water tanks.*

3. Installation

We'll connect your brand new combi boiler. This includes connecting it to the existing heating system, installing a new control or, connecting it to an existing one and if required, altering pipework.

4. Commissioning  

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.

5. Final Checks

Over to you, our experts will demonstrate how to use the new boiler, explain what has been carried out during the install and show you how to operate your new boiler.

6. Clean Up

Your installation is now complete! Don't worry about the mess, our engineers will ensure your property is left exactly how they found it.

If you would like to find out more about the installation process, check out our Padly boiler installation guide.

Your FAQs answered

While our experts have provided an in-depth overview about converting to a combi boiler, we understand that, that's not everything! That's why we've answered some popular frequently asked questions that you may have about swapping to a combi boiler or, about combi boilers in general.

Will you remove my tanks?

Yes, our engineers will take away your tanks.*

Where is the best place to put a combi boiler?

Our certified engineers recommend, if possible, to place a combi boiler near a sink, whether that be in the kitchen or a utility room. This is because it is more ideal as it minimises disruption within your home, as well as the need for additional pipe-runs.

How much does a combi conversion cost?

Converting to a combi boiler can often be less expensive to install than system or conventional boilers. This is mainly because combi boilers have simpler setups, without the need for a separate water tank or cylinder. However, it is crucial to express that costs can widely vary depending on the specific boiler model and the complexity of the installation.

So, is converting to a combi boiler worth it?

Converting to a combi boiler offers numerous benefits, including space-saving design, energy efficiency, on-demand hot water, cost savings, and reliability. Whether it's worth it depends on your specific needs and circumstances, but for many homeowners, the advantages of a combi boiler make it a worthwhile investment in terms of comfort, convenience, and long-term savings.

To find out if converting to a combi boiler is right for you, get a personalised quote today! Don't forget, our team at Padly are on hand and with you every step of the way, so if you have any further queries please do not hesitate to contact us.

*Due to health and safety reasons, we will only remove tanks that are made of plastic.