Skip to content

Combi vs System Boiler: How Different are the Running Costs?

Many homeowners question whether a system or combi boiler is best suited to their home. In this guide, we’ll look at the differences between the two, including installation costs, running costs and general maintenance.

Get a Quote Request a Call
piggybank on top of radiator

Boilers are an essential part of any home, and it is vital you have a boiler which aligns with your lifestyle and the demands of your lifestyle. Due to this, it leaves many homeowners questioning whether a system or combi boiler is best suited to their home. 


In this guide, we’ll look at the differences between the two, including installation costs, running costs and general maintenance.


Key Points:


  • Combi boilers are compact, making them ideal for smaller properties

  • System boilers are ideal for homes with more than 2 bathrooms

  • Both properties have their own pros and cons depending on your lifestyle and heating and hot water demands

Differences between combi and system boilers

The main difference between a combi and system boiler is that a combi boiler provides heating and hot water instantly. A system boiler, however, is designed to work with a water cylinder to provide hot water. 


System boilers offer an excellent supply of hot water, however, the water tank does take up a lot of space. Combi boilers are much more energy efficient than system boilers and they don’t require a water cylinder since the boiler heats the water as and when you need it. 

Chat to us about your Boiler Needs Speak to an Expert

Combi boiler vs system boiler: Installation costs

Typically, the cost of installing a new combi boiler will be anywhere between £1,500 and £4,000. This includes the cost of the materials and the installation of the new boiler. Although these costs are generally a rough estimate, new combi boiler prices can vary depending on the make and model, location of the boiler and whether it’s a straight swap for a new combination boiler or if you’re having your system converted to a combi system. 


Generally speaking, system boilers aren’t usually installed anymore and instead, they are replaced by new combi boilers, unless your particular circumstances don’t require a combi. You can expect to see costs of anywhere between £3,000 and £5,000. This price will likely include the cost to remove the old system boiler, the cost of installing the new boiler and any labour costs such as changing and repositioning pipework. 


Combi boiler vs system boiler: Running costs

Combi boilers are more energy efficient than system boilers, making them potentially cheaper to run. However, this really depends on your hot water and heating consumption. A system boiler may actually end up cheaper if you use more hot water regularly since it has a storage tank. 


Combi boilers will usually waste more water and electricity when heating the water since it flows on demand. This can be an issue for large volumes of water, so the main consideration needs to be your home size and your water demand. 


Combi boiler vs system boiler: Maintenance costs

The average cost of servicing a boiler in the UK is generally the same for each kind of boiler, with prices ranging from £120-£130 on average, including VAT. 


However, if you need parts of your boiler replaced or repaired, you can generally expect to pay more if you have a system boiler. This is because the parts for combi boilers are much more readily available. Combi boilers also have fewer parts and are generally easier to access, making them easier and less expensive to fix. 

Should I replace my system boiler with a combi boiler?

Generally speaking, there are a few factors you should consider when thinking about upgrading your heating system. One of the main things you should consider is the size of your home. Combi boilers are usually best suited to homes with 1-2 bathrooms, whereas system boilers are suited to homes with more bathrooms and demand. 

For more information on whether or not you should upgrade your system boiler to a combi boiler, head over to our dedicated guide on combi boilers vs conventional boilers.

Find Us On

Unit 11 Eton Business Park

Eton Hill Road, Radcliffe, M26 2ZS

Opening Times

Mon – Fri 8am – 5pm

Call Us Today

0161 879 4949
Get In Touch
0 of 350