Strom AuraHeat 13.5kW Single Phase Stored Combi Boiler - Electric Combi Boiler with 35L Integrated Stainless Steel Buffer Cylinder

Rather than feeding cold mains water directly to the heat exchanger, the AuraHeat stores water at up to 80°C in the 35L stainless steel tank, then mixes it with incoming cold mains water through a digital programmable blending valve before returning the blend to the heat exchanger for final temperature trim. The result is that the heat exchanger sees pre-warmed water instead of cold water, enabling it to sustain flow rates associated with gas combis. The hotter the tank, the longer it can keep the blended supply above the target temperature — extending the effective hot water duration well beyond what the 35L volume alone would suggest.

The 35L tank can be operated in four ways to match how the household uses hot water. Always On keeps the tank heated continuously at the set temperature, ready for immediate use. Always Off leaves the tank unheated and allows the boiler to function as a standard instant electric combi. Boost Once heats the tank a single time in around 20 minutes, useful when a bath is anticipated. Timed On heats the tank at the same time each day, allowing the household to schedule heating around off-peak tariffs or daily routines.

Strom's heat exchanger distributes the heating load across multiple independent strands, transferring heat evenly across the whole surface. This eliminates the concentrated hotspots that cause limescale to bake onto single-element designs, and keeps the water circuit physically separated from the heating strands — reducing corrosion and allowing individual strand replacement rather than replacing the whole unit.

Because each strand can be switched independently, the boiler modulates output from as little as 1kW up to 13.5kW in fine steps to match the central heating demand at any given moment. The wider span between minimum and maximum output makes this model better suited to larger properties with a wider swing between mild and cold day demand, without the short-cycling that a single fixed-output element would cause.

The domestic hot water side of the cylinder is heated indirectly via an integrated coil, keeping the DHW circuit separated from the central heating water. This limits contact between the DHW and the coil surface, giving significantly better scale resistance than a direct-immersion arrangement — important in hard water areas where limescale build-up would otherwise shorten element life.

A built-in diverter valve automatically switches the heat exchanger's output from central heating to DHW as soon as an outlet opens, mirroring the priority logic of a gas combi boiler. Programmable parameters then let the installer or user set whether stored volume, instantaneous flow rate, or a balance of both takes precedence during draw-off — giving per-household tuning that a fixed factory setting cannot provide.

The SBSP13SC shares the same 920 × 570 × 300mm casing as the 9.5kW SBSP9SC and the same 35L stainless steel tank, but delivers 13.5kW of heat output and a faster tank recharge of 20 minutes. For properties with a higher calculated heat loss or greater hot water demand, stepping up to the 13.5kW adds no extra wall space requirement — only the electrical supply needs to be sized for the higher current draw.

With no combustion, the AuraHeat produces zero local carbon monoxide and requires no flue terminal, soffit clearance, or terminal guard. This opens siting options unavailable to gas or oil boilers: internal cupboards, flats, and properties where cutting through an external wall for a flue is impractical or impossible.