What is a Combi Boiler?

Every year, we find ourselves having lengthy discussions with our customers over boilers ahead of the winters. A question customers ask us quite often is “What is a combi boiler?”. That prompted us to compile an article on the basic things you need to know about what is a combi boiler.

A combi or combination boilers serve two purposes. They heat a house and providing hot water on demand. They are the most popular type of boilers in the UK as their space-saving design has only a single unit. Combi boilers do not need a separate water heater like other traditional boilers.

How do Combi Boilers Work?

A combination boiler has two main jobs: to run the central heating system and to provide hot water. Two separate heat exchangers located inside a single, compact box, do these two jobs.

The primary exchanger heats the water that flows in the pipelines of the central heating system. The water, in turn, warms up the radiator. This water running through the house and the heating system gets recycled. Its temperature is maintained at a steady level. The boiler is connected to the thermostat in the radiator to control the temperature, turn on, and turn off.

The secondary heat exchanger provides hot water on demand. Combination boilers are unlike traditional boilers that had separate water storage tanks. They are, instead, connected to the water mains. When a tap joined to the system turns on, the water from the mains passes through the secondary exchanger, gets heated, and flows out of the tap. You get hot water almost instantly and at the same pressure that it flows through the main lines. The boiler is always on standby, waiting for a tap to turn on.

The primary and secondary heat exchangers never work at the same time. This is to ensure that recycled water from the heating system does not enter the home taps. A valve connected to the supply system shuts off, for a while, the radiator pipe’s supply when a hot water tap is open. Don’t worry about this, because this momentary break does not cause any drop in your home’s ambient temperature.

Types of Combi boilers

Gas, oil, or electricity can fuel the heat exchangers of a combi boiler. Depending on how they run, combi boilers can be of the following types:

  1. Natural gas combi boiler: This is the most common type of combi boiler found in UK homes. It is usually the best option given its low running cost. This is especially true if your home is connected to the gas supply network
  2. Oil combi boiler: This is your best bet if your home is not connected to the gas lines. If you decide to buy an oil combi boiler, you will need to install an oil tank outside your home and refill it as and when needed.
  3. LPG combi boiler: These boilers run on liquefied petroleum gas (LPG). LPG is a combination of hydrocarbons obtained during the extraction and refining of oil and natural gas. Like oil boilers, LPG boilers also need you to put in a tank outside your house. The tank must be refilled once it runs low.
  4. Electric combi boiler: The design of this one is slightly different from the others. The electricity does not heat the exchangers directly. Instead the water–for the radiators and the taps – passes over an electric element and gets heated. The working mechanism is much like immersion rods used to heat water. This design is suitable for smaller homes that are not connected to the gas grid and find oil to be an expensive alternative.

To Conclude

It’s important to choose the right boiler type on your hot water demand and heating requirements. Additionally, the boiler must be able to cope with the water pressure of the main supply lines in your home.

Heating Connect have years of experience in working with boilers, we can help you choose the perfect one. All you need to do is give us a call. And we will schedule an appointment according to your convenience. Someone from our team will visit you to check your requirements and infrastructure. They will then give you impartial recommendations.

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