Boilers: Compare features & prices

Side-by-side comparison

LPG convertible
Whether the boiler can be converted to burn liquid petroleum gas.

Heat outputs available (kW)
The different sizes (heat output in kW) of the boilers available in this boiler range.

Weight (kg)
The lift weight for installing the boiler, as stated by the manufacturer.

Size (HxWxD in cm)
Measurements of the boiler excluding any space needed for ventilation or cables.

Boiler volume (litres)
Volume of the boiler excluding any space required for ventilation or cables.

Clearance at the top (cm)
A clearance is the space required around a boiler casing to allow safe operation or access for servicing.

Left side clearance (cm)
A clearance is the space required around a boiler casing to allow safe operation or access for servicing.

Right side clearance (cm)
A clearance is the space required around a boiler casing to allow safe operation or access for servicing.

Clearance at the bottom (cm)
A clearance is the space required around a boiler casing to allow safe operation or access for servicing.

Front clearance in operation (cm)
A clearance is the space required around a boiler casing to allow safe operation or access for servicing.

Front clearance for servicing (cm)
A clearance is the space required around a boiler casing to allow safe operation or access for servicing.

Minimum heat output (kW; non-condensing)
The manufacturers' claimed minimum heating output in non-condensing mode.

Maximum heat output (kW; non-condensing)
The manufacturers' claimed maximum central heating output in non-condensing mode.

Maximum heat output (kW; condensing)
The manufacturers' claimed maximum central heating output in condensing mode.

Efficiency (% SAP 2009)
Measured by an independent laboratory, this is the measured energy efficiency of the boiler, including heat and hot water; it is calculated to an industry standard called SAP 2009.

SAP winter efficiency (%)
Measured by an independent laboratory, this is the measured energy efficiency of the boiler, including heat and hot water; it is calculated to an industry standard called SAP 2009.

SAP summer efficiency (%)
Measured by an independent laboratory, this is the measured energy efficiency of the boiler, including heat and hot water; it is calculated to an industry standard called SAP 2009.

NOx Emission class
The official classification for the emission of the polluting gases NOx. Class 5 is the best class with the lowest NOx emissions.

Electricity usage on standby (W)
The amount of electricity used when the boiler is not firing.

Electricity usage when firing (W)
The amount of electricity used when the boiler is firing.

Hot water flow (l/min) @ 30 degrees
The flow rate is given according to a certain temperature achieved, assuming that the boiler increases the temperature of the water by 30, 35 or 40 degrees. The more the water temperature is increased the lower the flow rate. It is not applicable to heat-only or system boilers which store hot water in a separate cylinder.

Hot water flow (l/min) @ 35 degrees
The flow rate is given according to a certain temperature achieved, assuming that the boiler increases the temperature of the water by 30, 35 or 40 degrees. The more the water temperature is increased the lower the flow rate. It is not applicable to heat-only or system boilers which store hot water in a separate cylinder.

Hot water flow (l/min) @ 40 degrees
The flow rate is given according to a certain temperature achieved, assuming that the boiler increases the temperature of the water by 30, 35 or 40 degrees. The more the water temperature is increased the lower the flow rate. It is not applicable to heat-only or system boilers which store hot water in a separate cylinder.

Hot water heating efficiency (%)
Measured by an independent laboratory, this is the measured energy efficiency of the boiler when it produces hot water; it is calculated to an industry standard called SAP 2009.

Concealed user controls
Are the user controls hidden behind a panel.

Heating temperature control
Lets you set the temperature of water in the central heating.

Hot water temperature control
Lets you set the temperature of the hot water supplied to the taps.

Reset control
Allows you to restart the boiler after problems are encountered.

System pressure gauge
Indicates the water pressure in the central heating system.

Mains on
Indicates that the boiler is switched on.

Burner on
Indicates that the boiler is heating.

Central Heating indicator
Illuminates when the boiler is in central heating mode.

Domestic hot water heater
Illuminates when the boiler is in domestic hot water mode.

Boiler output temperature
The temperature that the boiler is set to heat to.

Overall energy efficiency
Boilers that have an efficiency of 88% or more and are therefore eligible for installation according to the Building Regulations Part L are awarded 5 stars for efficiency.

Brand reliability rating
Based on the results of our annual boiler reliability survey of Which? members. This applies only to boilers up to six years old, bought between 1 April 2005 and the end of May 2011.

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