Back Boiler or New Efficient Combi Boiler? What You Need To Choose!

Back boilers typically operate at around 60–70% efficiency when new, but this efficiency decreases over time due to aging components and outdated technology. They require both a fireplace for installation and a separate hot water tank, which takes up considerable space. The system is gravity-fed and slower to heat, making it less efficient for modern household demands. Safety can also be a concern, especially without regular servicing, as older back boilers lack many of the built-in safeguards found in newer systems.

In contrast, modern combi boilers offer much higher efficiency typically between 90–98% thanks to condensing technology that reuses waste heat. They are compact, wall-mounted units that provide both heating and hot water directly from the mains, eliminating the need for a storage tank. Combi boilers heat water on demand, offer quicker space heating, and come equipped with smart controls for remote operation and better energy management. Because of their efficiency and safety features, they are more likely to qualify for government schemes like ECO4.