The difference between a system boiler and a heat pump

The main differences between a system boiler and a heat pump are how they work, the fuel they use, and their environmental impact.

Both system boilers and heat pumps require a hot water cylinder, ensuring a steady flow of warmth and hot water to your home. While system boilers harness gas or oil to heat your water directly, heat pumps use electricity to intelligently draw heat from the environment to transfer warmth inside your home.

Both systems use hot water cylinders, however the role and function of a hot water cylinder differs depending on whether it’s used with a system boiler compared to a heat pump.

System boilers and heat pumps differ in their flow temperatures; system boilers can reach 65° for faster heating, whereas heat pumps generally operate at around 55°, leading to a slower heat-up process.

• A system boiler heats the system water, which can then be directed through the heating pipework in the cylinder, and this heats up the cold domestic water in the cylinder.
• System boilers can use either a vented or unvented cylinder.
• The cylinder stores hot water that is ready to be used on demand, but the system boiler is responsible for generating that hot water quickly.
• A system boiler takes water directly from the mains and has the components for heating water built in.

• With the heat pump running at a lower temperature, the thermal efficiency of the hot water cylinder plays an important role in storing hot water to the desired temperature.
• Heat pumps require a high recovery cylinder which feature a higher KW rated coil with a larger surface area for efficient heat exchange. In comparison, a boiler cylinder typically has a smaller kW rated coil.
• A large heat pump will require a bigger hot water cylinder to ensure there is enough stored hot water.
• Heat pump cylinders are designed to work efficiently with the lower temperatures generated by heat pumps and usually come with large coils for efficient heat exchange.

The main difference in a hot water cylinder for a system boiler compared to a heat pump is the efficiency, sizing and heat production. A heat pump system needs a larger cylinder as the heating process is slower and operates at a lower flow temperature, whereas system boilers can produce hot water quickly, and therefore usually need a smaller hot water cylinder.

Heat pumps and system boilers have a number of differences and are both efficient in different ways.

Both system boilers and heat pumps use hot water cylinders to store energy, however heat pumps extract heat using an electric compressor, whereas system boilers use gas or oil. System boilers are easy to install in existing homes with high heating demands. Heat pumps on the other hand, offer a higher efficiency with lower carbon emissions.

Heat pumps also have a higher installation cost and take longer to commission compared to a system boiler but are more efficient.