Combi Boilers versus Conventional Boilers

Purchasing a new boiler is a big decision – it’s the hot water and energy hub of your house which keeps everyone happy. Whether you had an old boiler which is past the point of servicing or repair, or are in a new property which requires a new boiler installation, there’s a few choices to make. 

These can mainly be ‘boiled’ down to the choice between a conventional or a combi boiler. One is not better than the other – they are just different and it’s important for you to know why and what those terms mean. You may even be about to switch from a conventional boiler to a combi boiler – so here are their pros and cons.

What is a Combination, or Combi, Boiler?

A combi boiler is a single unit central heating boiler system and water heater. When you turn on the hot water tap, it heats on demand. This eliminates the need for the storage tank which is required by a conventional boiler.

How does a Combi Boiler work?

A combi boiler is one compact system without a hot water cylinder or an external cold water tank. Combi boilers heat water instantly and work with radiators to warm up your home. 

A heat exchanger inside the combi boiler transfers the majority of the heat from the burnt gas inside the boiler and then delivers hot water to taps and radiators. Where it diverts the water to is decided by control valves.

How does that compare to a Conventional Boiler?

As conventional boilers use a water storage tank that means that the water inside a combi boiler will be cleaner and less prone to sludge build up. You should avoid drinking water that comes from a conventional boiler – whereas combi boilers are directly linked to the mains water system which is tested for safety. Convention, or traditional boilers, don’t heat on demand so you have to wait for them to warm water up when you turn them on. 

How does a Conventional Boiler Work?

A conventional boiler has two tanks – a cold-water supply and a hot water storage tank. Water is supplied through a cold water supply tank, heated and then stored in the hot water tank. To keep a house warm, the water from the hot tank pumps around the central heating system.

What are the drawbacks of a Conventional Boiler?

Aside from the water purity issues mentioned above, conventional boilers can also be prone to air locks or low pressure problems. They also need a lot of space and so are not really suited to flats and smaller homes but are typically found in rural properties. 

Why would I have a Conventional Boiler installed?

It may just come down to the type of property you have – some older properties are better set up to suit conventional boilers. 

Furthermore they are great at servicing large households. Even if multiple taps are in use it does not affect the temperature or water pressure. Everyone will get hot water until the cylinder needs refilling. 

Should I get a Combi Boiler installation?

Combi boilers are popular in UK households because they are highly efficient and can save money on your heating compared to a conventional boiler. According to the Energy Saving Trust you can save up to 40% on your energy bill if you replace your old boiler with an A-rated combi boiler.

Combi boilers are compact in size which makes them a good choice where space is limited. The installation process itself of a combi boiler may also be quicker. 

What are the negatives of a combi boiler?

Combi boilers are only as good as the water system they are hooked up to. If your mains pressure is not up to scratch neither will your combination boiler be. Furthermore the lack of a hot water storage tank means that if there is a boiler breakdown there is no backup and your house will be without hot water. 

Water from a combi boiler can lose heat very fast if the hot water cylinder is not insulated properly. 

Who can help me make the decision?

Get your boiler installation decision right. Call in the experts at MP Plumbing. We have years of experience at getting the right type of boiler in a property and are available 365 days a year to come out and give you a quote. 

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