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What is a Combi Boiler?

What is a Combi Boiler?

What is a Combi Boiler?

A combi boiler (short for combination boiler) is a type of boiler that combines two functions in one compact unit:

  1. Heating your home (via radiators or underfloor heating).
  2. Providing hot water on demand (to taps, showers, etc.).

Unlike traditional boilers, combi boilers don’t require a separate hot water storage tank or a cold water storage tank. They heat water directly from the mains supply whenever you need it.


How Does a Combi Boiler Work?

A combi boiler draws water directly from the mains supply. When you turn on a hot tap or shower, the boiler senses the demand and starts heating water instantly. It uses a heat exchanger to transfer heat from the boiler’s burner to the water supply.

For heating your home, the boiler sends hot water through your radiators or underfloor heating system. A built-in control system ensures the boiler prioritizes hot water for taps or showers over central heating when both are needed at the same time.

How Does a Combi Boiler Work?

Key Features of a Combi Boiler:

  • Compact Design: Ideal for smaller homes or spaces where installing separate tanks isn’t feasible.
  • On-Demand Hot Water: Delivers hot water instantly without waiting for a storage tank to heat up.
  • Energy Efficiency: Since water is heated only when required, there’s less energy waste compared to systems that keep water heated in a storage tank.
  • Simple Installation: Requires fewer components (no storage tanks), making installation quicker and less disruptive.

Advantages and Disadvantages of Combi Boilers

Advantages

  1. Space Efficiency:
    No need for a hot water storage cylinder or cold water tank in the loft, freeing up valuable space.
  2. Energy Efficiency:
    Only heats water when needed, reducing energy waste.
    Many models are over 90% efficient, meaning lower energy bills.
  3. Quick Installation:
    With fewer components compared to traditional systems, installation is faster and usually cheaper.
  4. Convenience:
    Instant hot water without waiting for a tank to fill or heat up.
  5. Cost Savings:
    Lower initial setup costs compared to traditional systems.

Disadvantages

  1. Hot Water Flow Limitations:
    The flow rate may drop if multiple taps/showers are used simultaneously, making it less ideal for larger households with high water demand.
  2. Dependence on Water Pressure:
    Requires good mains water pressure for optimal performance. Homes with low water pressure might need a pump or pressure-boosting system.
  3. Not Ideal for Large Homes:
    Homes with multiple bathrooms or high heating needs may benefit more from a system boiler with a storage tank.

  4. No Backup Hot Water:
    Since there’s no storage tank, if the boiler breaks down, you won’t have access to any stored hot water.

Key Factors to Consider When Choosing a Combi Boiler

  1. Size and Output:
    kW Rating: The higher the kW rating, the more powerful the boiler.
    Choose a boiler suitable for your home’s heating and hot water demands.
  2. Water Pressure:
    Ensure your mains water pressure is adequate for a combi boiler.
  3. Fuel Type:
    Consider the availability and cost of fuel in your area.
  4. Energy Efficiency:
    Look for models with high efficiency ratings or those recommended by energy-saving programs.
  5. Smart Features:
    Modern combi boilers often come with smart thermostats or remote control options.
  6. Brand and Warranty:
    Opt for reputable brands with good warranties and customer support.
  7. Installation and Maintenance Costs:
    Factor in the costs of professional installation and regular servicing.

Combi boilers are popular in modern homes and are particularly suitable for smaller to medium-sized properties. They offer convenience, energy efficiency, and a compact solution for heating and hot water needs.


Ideal Homes for a Combi Boiler

  • Flats and Smaller Houses: Perfect due to their compact design.
  • Medium-Sized Homes: Work well if there’s moderate hot water demand.
  • Homes Without a Loft: A great solution when a loft isn’t available for a cold water tank.

Combi Boiler Installation by North Somerset Heating

We are Gas Safe registered Heating Engineers that install combi boilers through North Somerset. We can advice you if a combi boiler is what your home needs. Click here for an online boiler quote!

Kevin is the boiler expert of North Somerset Heating.