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System Boilers

What is a system boiler?

System boilers are self-contained units that contain many of the major heating components your home requires all compact into the boiler. They don't require a cold-water tank or expansion tanks as the heating circuit is pressurized by the internal pressure vessel inside the boiler. Therefore they are ideal for homes with limited space – or homes looking to make the most out of loft space.

Find out if a system boiler is the perfect pairing for your home by taking our quick quiz below.

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 system boiler works. Step one shows a house with a boiler in the bottom floor and a separate water tank in the upstairs with a caption of "Cold water from the mains fills the heating circuit and is pressurised by the boiler". Step two shows the system boiler up close with the caption "The water is heated by the boiler and pumped to the three-port valve". Step three shows the water tank with the caption "Water is diverted to the hot water cylinder and stored in the cylinder until needed". Step four shows a bath with a shower illustration with the caption "The hot water is the sent to the taps"
The ins and outs of your new boiler

How does a system boiler work?

System boilers operate in much the same way as a regular (Open vented) boiler does. The big difference is that system boilers have a circulating pump inside the boiler, alongside a pressure vessel. These components pressurize the heating circuit, making it much more efficient than a regular (Open vented) boiler and eliminates the need for the small feed and expansion tank that is usually located in the roof space.

Heating and hot water waiting for you

What are the benefits of choosing a system boiler?

Energy efficient

Water cylinders and tanks of a system boiler can be used in conjunction with solar panels after installation, resulting in a reduction in your carbon footprint and hefty energy bills.

Higher flow rates

If you end up having a greater need for hot water than expected over the coming years, you can install a bigger cylinder with a system boiler, whereas other types of boilers such as combis have a limited flow of hot water.

Hot water ready

System boilers benefit from having pre-programed controls that you can oversee, meaning you can avoid waiting for your water to heat up, it'll be in your hot water cylinder ready for you.

Choose the best for your home

Is a system boiler right for me?

System boilers are the most installed boilers in the UK, and for a good reason, like combi boilers, they work by drawing water straight from the mains providing your central heating whilst also generating hot water to be stored in a cylinder for later use.

System boilers are the perfect pairing for larger homes with more than one bathroom, for a family of four or more, a system boiler could be the most efficient and convenient way to heat your home and your water.

What you need to know

The straight forward System boiler installation process



Our engineers will carry out a full assessment of your heating and hot water requirements, including routing of pipes and wiring, and preparation of the site



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



Our engineer will install the main boiler, then connect it to the heating system and the hot water cylinder



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 system is right for my home?

When considering boiler ‘size’ it’s best to not think literally. The size of your boiler will typically refer to a boiler’s output/power, not the physical dimensions of the boiler. However, as stated above if you’re looking for a boiler that can fulfil hight hot water demand for various bathrooms, this is the best and most economical option for your home.

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 advantages of installing a system boiler in my home?

System boilers offer several key benefits. Unlike combi boilers, they have a separate hot water cylinder, which allows them to provide hot water to multiple outlets simultaneously. This makes them an excellent choice for larger homes or families. They're also more compact than traditional boilers because they incorporate many of the components that would be separate in a conventional system, and they can work with solar thermal systems to lower your energy bills and carbon footprint.

How does the cost of installing a system boiler compare to other types of boilers?

The cost of installing a system boiler can vary greatly based on the complexity of the installation and the model of the boiler itself. While they may be more expensive to install than combi boilers because of the need for an additional hot water cylinder, they can be cheaper than conventional boilers as they don't require a tank in the loft.

Can a system boiler help me save on my energy bills?

Yes, modern system boilers are designed to be highly efficient and can help you save on your energy bills. They are also compatible with solar thermal energy, which can reduce your reliance on gas or electricity for hot water, potentially leading to significant savings.