The Pros and Cons of Owning a Combi Boiler

The Pros and Cons of Owning a Combi Boiler

The following contribution is from another author.

Households across the country are reckoning with their relationship to their central heating, as energy bills have risen to a historic high – and are projected to rise even further before next winter. The home’s boiler is a crucial part of its energy usage, providing hot water and central heating year-round.

With more efficient models available on the market today, switching could be a beneficial long-term move. But should you get a new combi boiler? Here are some advantages and disadvantages of the modern boiler type, to help you make a decision.

PRO – Size

Combi boilers take up much less space than conventional boilers, giving you more room in your home for storage and other uses. This is because conventional boiler systems make use of separate tanks for hot and cold water. The hot water tank tends to be stored in a home’s ‘airing cupboard’, in a bathroom or utility space, while cold water tanks are often stored in lofts. Combi boilers draw water straight from the mains, meaning both utility and loft storage space is returned to you.

CON – Single Point of Failure

Having a separate tank for hot water, as with conventional boiler systems, means you can continue to benefit from your hot water taps and central heating even in the event of a boiler breakage. Combi boilers, however, heat water from the mains in situ, meaning that if your combi boiler breaks down you will have no backup hot water.

PRO – Immediate Results

Combi boilers are directly hooked up to the mains, meaning that they take and heat water when required – whether you turn on a hot tap, take a shower or turn the heating on. Older conventional boiler systems would heat the home’s radiators and the contents of a hot water tank at the same time, with said contents kept warm via insulation. As such, it is possible for the hot water to ‘run out’, requiring the boiler to be turned on again to heat the whole tank. This is not necessary with combi boilers.

PRO – Efficiency

Combi boilers, by virtue of their compact design and on-demand water heating, are a more efficient form of boiler than older conventional systems. This is because those older systems would have to keep their separate hot water cylinder up to temperature, even if all that water was not going to be required. Combi boilers heat water quickly as and when it is needed, bringing down energy usage and resulting bills in the process.

CON – High Demand = Low Pressure

Conventional boiler systems would have their water storage systems at height, enabling gravity to assist water flow and produce high pressure. Combi boiler systems rely on mains pressure alone to serve the home, which can be too low for some applications. The more water-dependent processes you attempt at the same time, the lower the pressure for each. Sadly, this also rules out power shower systems from combi boiler homes.


Eric is the creator of At Home in the Future and has been a passionate fan of the future since he was seven. He's a web developer by trade, and serves as the Director of Communication and Technology for a large church in Nashville, TN (where he and his family are building a high tech home in the woods).

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