Combi Vs System Boiler – Know The Differences

When it comes to shopping for boilers, it’s not an easy task by any means, for any homeowner. The boiler that you’ll choose will stay with you for the next couple of years, at least. This means you have to be spot-on with your decision, otherwise, you can regret your purchase. In recent years, homeowners are slowly getting attracted to combi boilers, but some people are still out there who prefer system boilers. But, which boiler would be the ideal choice for you?

To help you know the differences between the same, we are going to compare system & combi boilers and thus find out the perfect one for your use case scenario. 

The Difference Between System & Combi Boilers

When it comes to physical size, both of them differ from one another. They also differ in the heating capacity and the way they produce the heat. 

According to a professional service provider offering combi boiler installation in the UK, system boilers heat their system from within. The system boiler will intake water from your house’s main water supply, heat it and then store the same inside a hot water cylinder. A heat exchange process is utilised to heat the water. When hot water is needed, the same is pulled from the cylinder. This means that the amount of hot water that you can obtain would be similar to the capacity of the cylinder. 

Alternatively, combi boilers proceed to heat the water directly from the main water supply inside your home. It will heat your water without storing it, which means that combi boilers don’t have any storage tanks or cylinders, unlike system boilers. As a result, combi boilers can continue heating the water and provide you with a constant supply of water, simultaneously. Such is the reason why combi boilers are also known as combination boilers.

Which Is The Best Option For You?

Merits Of Combi Boilers


  • Efficiency


Since combi boilers use modern technology, the process of heating water is very efficient. It’s said that combi boilers are up to 92 percent efficient, leading to lower energy bills & carbon footprint.


  • Hot Water Anytime


Combi boilers will start heating water the moment you turn them on. There’s no storage cylinder, which means there’s no loss of heat and you can enjoy hot water any time. 

Merits Of System Boilers


  • Offers Hot Water Quickly


Since system boilers come with an in-built storage tank, you can obtain hot water much quicker without having to wait for the same. 


  • Great For Large Families


A system boiler can deal with water demands from multiple outlets, making it a great option for large-sized families. 

Therefore, at the end of the heyday, it all comes down to your preferences. We sincerely hope that our comparison has been helpful. 

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