Which boiler do I need?

Baxi makes three different types of boiler: combi, heat only and system boilers. All of these products include the latest condensing technology, so they are highly energy efficient and very cost effective to run.

 

Combi boiler

Combi (or combination) boilers are the UK's most popular type of boiler for gas central heating and domestic hot water. They are easy to install, simple to use and economical to run.

A combi boiler only heats water when a hot tap or shower is turned on, ensuring maximum efficiency. There is no need to find space for a water storage cylinder or have a tank in the loft. Hot water is delivered to your taps t mains pressure, so you can enjoy a powerful shower without the need for a pump.

 

 

 

 

Heat only boiler

Heat only boilers are also known as 'regular' or 'conventional' boilers. If you are replacing an old boiler and have a small expansion tank and a larger cold water storage cistern in your loft, your probably already have a heat-only boiler.

Heat only bolers are usually installed on an open vented system. The system will usually comprise two tanks in the loft, a hot water storage cylinder in the airing cupboard and a separate pump.

 

 

 

 

System boiler

If you live in a home with more than one bathroom or require more hot water than can be provided by a combi boiler, then a system boiler could be your perfect heating and hot water solution.

A system boiler pumps hot water to the radiators and a sealed hot water storage cylinder. Most of the major components of the heating system, including the pump and expansion vessel, are built into the boiler, making installation easier, tidier and more efficient, and also simplifies servicing.

 

 

  

 

Type of home 1 bedroom 2-3 bedrooms 4 bedrooms 5+ bedrooms

Number of bathrooms

1

1

1

1

1

1

Multiple

Number of shower rooms

-

1

-

1

-

1

 Multiple

Suggested combi boiler

24kW

33kW

28kW

40kW

33kW

See below*

See note*

Suggested heat only/
system boiler

12kW + cylinder

15kW + cylinder 

15kW + cylinder

18kW + cylinder 

24kW + cylinder

30kW + cylinder

30kW See note** + cylinder

Note*: For homes with multiple bathrooms or high demand fittings (such as multi-jet showers) we recommend a hot water storage system in order to deliver sufficient flow rates to satisfy simultaneous demand. Please refer to Heatrae Sadia for product details and further sizing guidance.

Note**: For larger homes the space heat demand may exceed 30kW, therefore requiring multiple boilers to provide adequate comfort levels. This is dependent upon a number of factors including location, insulation levels, occupancy patterns and system configuration.  

Important: This representative information is provided for reference only. A Gas Safe Registered installer should be consulted prior to final specification of a boiler or system as there are a number of factors which may influence the final selection such as age of property, insulation levels, exposure, type of hot water fittings etc.
Whilst all reasonable efforts are made to ensure the accuracy and completeness of this information, Baxi Heating UK Ltd cannot accept any liability, express or implied, in the event of error or omission.

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