A combi boiler is one of the most popular installs we carry out for homes across Exeter and Devon – compact, efficient, and providing both central heating and hot water on demand. This guide covers what to expect, what it costs, and how to get the installation right, with the work carried out by our Gas Safe registered engineers.
What Is a Combi Boiler?
A combi boiler (short for combination boiler) is a compact, all-in-one heating system that provides both central heating and hot water on demand. It doesn’t require a separate hot water cylinder or cold water storage tank, which makes it ideal for homes where space is at a premium.
Thanks to their efficiency and convenience, combi boilers are now the most popular boiler type in the UK.
If you’re considering a combi boiler installation, this guide will walk you through everything you need to know – from costs and timescales to choosing the right model and installer.
Why Choose a Combi Boiler?
Here are some of the main reasons homeowners in Exeter and across the UK choose a combi boiler:
- Compact: Fits neatly in a kitchen cupboard or airing cupboard
- Efficient: Modern combi boilers are over 90% efficient
- Hot Water on Demand: No waiting for a tank to heat up
- Lower Energy Bills: You only heat water when you need it
- Simplified Installation: Fewer components to install and maintain
- Ideal for Small to Medium Homes” Especially with one bathroom
Is a Combi Boiler Right for Your Home?
Combi boilers are best suited for:
- Flats, bungalows, or small-to-medium homes
- Homes with one bathroom and moderate hot water usage
- Households that don’t need to run multiple showers or taps at once
If you have a larger home with multiple bathrooms or very high hot water demand, a system boiler might be a better fit. Our engineers can help you assess your home’s needs before committing.
What’s Involved in a Combi Boiler Installation?
Here’s a step-by-step look at what to expect during a typical combi boiler installation:
1. Initial Home Survey
Before anything is installed, a qualified heating engineer will visit your home to:
- Assess the size of your property and number of bathrooms
- Check your current heating system
- Determine your hot water usage
- Recommend the best combi boiler model and size
This ensures you get a boiler that’s efficient and powerful enough for your household.
2. Removing the Old Boiler
If you’re replacing an existing boiler, your installer will disconnect and safely remove it. This may include removing a hot water cylinder or cold water tank if switching from a regular or system boiler.
3. Installing the New Combi Boiler
The new boiler will be installed in a suitable location. Often where the old one was, or somewhere with easy access for maintenance and ventilation.
The engineer will:
- Fit the new unit
- Connect it to your gas supply, radiators and water system
- Install the flue (the pipe that removes waste gases)
- Add any smart thermostats or heating controls
- Test the system thoroughly
4. Flushing the System (If Needed)
If your radiators or pipework contain sludge or debris, a power flush may be carried out to prevent damage to your new boiler and improve heating performance.
5. Testing and Commissioning
Once everything is installed, the engineer will test the system, check for leaks, and ensure your new boiler is running safely and efficiently.
They’ll also walk you through how to use it and leave you with all relevant paperwork, including your Gas Safe certificate and manufacturer warranty.
6. Aftercare and Servicing
It’s important to get your new boiler serviced annually to keep it efficient, safe, and to maintain the warranty. Home Exeter can provide ongoing servicing and maintenance to keep your system in top shape.
How Long Does Combi Boiler Installation Take?
For a like-for-like replacement (e.g. swapping an old combi for a new one), installation usually takes one day.
If you’re converting from a system or regular boiler, the job is more complex and can take two to three days, depending on:
- How much pipework needs changing
- Whether tanks or cylinders need removing
- Whether a power flush is required
We’ll always aim to minimise disruption and leave your home clean and tidy.
How Much Does Combi Boiler Installation Cost?
Prices vary based on the brand, size of the boiler, and complexity of the installation, but here’s a rough guide:
| Installation Type | Estimated Cost (Including Boiler) |
|---|---|
| Combi to Combi Replacement | £1,800 – £2,800 |
| System to Combi Conversion | £2,500 £3,500 |
| Regular to Combi Conversion | £2,800 – £4,000 |
These are general estimates. For an accurate price based on your home and needs:
→ Get your free, no-obligation boiler quote here
What Are the Best Combi Boilers in 2025?
Here are some of the top-rated combi boiler models available in the UK right now:
- Worcester Bosch Greenstar 4000: Reliable and quiet with up to 10-year warranty
- Vaillant ecoTEC Plus: Highly efficient and great for smart home integration
- Ideal Logic+ Combi: Compact and cost-effective, perfect for smaller homes
- Viessmann Vitodens 050-W: German engineering with sleek design and smart features
- Baxi 800 Combi: British-built with excellent support and performance
Our engineers can help you choose the right model based on your home size, budget and preferences.
Who Should Carry Out the Installation?
Always choose a Gas Safe registered engineer to install your combi boiler. It’s a legal requirement and ensures:
- Your safety
- Proper certification
- Warranty protection
- Full compliance with building regulations
At Home Exeter, all our heating engineers are fully qualified and Gas Safe registered. We pride ourselves on quality workmanship, clear pricing, and exceptional aftercare.
FAQs: Combi Boiler Installation
Do I need planning permission to install a boiler?
No, not for most domestic installations. However, the flue must be correctly positioned, which your installer will handle.
Can I install a combi boiler myself?
Absolutely not. It’s illegal to install a gas boiler unless you’re a certified Gas Safe engineer.
Will I need to upgrade my radiators?
Not always, but your engineer will inspect them and recommend changes if they’re old or inefficient.
What size combi boiler do I need?
This depends on your home’s size and hot water usage. Typically:
- 24–27 kW for flats and small homes
- 28–34 kW for medium homes
- 35–42 kW for large homes or high demand
How soon can you install a new combi boiler?
We aim to book installations quickly, especially if your current boiler has failed. Contact us to check availability.
Ready to Install Your New Combi Boiler?
A new combi boiler is a smart investment – cutting energy bills, improving comfort, and freeing up space.
At Home Exeter, we make the process easy from start to finish. Whether you’re replacing an old unit or switching from a traditional system, we’ll handle everything with care and precision.
→ Click here to get your instant boiler installation quote
We’ll help you choose the best boiler for your needs, install it safely, and keep it running efficiently for years to come.
