For the majority of homes, a combination boiler is the most energy efficient option, as it does not require a permanent store of hot water and only heats the water when there is a demand. However, for larger properties or households with above average hot water requirements a different approach is necessary.

In these situations, a combination boiler is often unable to provide the required flow rate of hot water. The traditional solution is to install a conventional boiler and hot water cylinder. However, because this type of system heats large amounts of water that may not be used, it is not the most efficient choice.

The innovative Alpha FlowSmart provides a solution to this problem. The complete system incorporating a flue gas heat recovery unit and thermal store, enables a combination boiler to meet the higher levels of demand and achieve a sustained flow rate of up to 18 litres per minute above 50°C – easily surpassing the performance of a 200 litre unvented cylinder where the temperature will begin to drop below 40°C after 10 minutes.

How FlowSmart works

  1. When there is a hot water demand, mains cold water flows into the GasSaver, where it is pre-heated using heat reclaimed from boiler flue gases.
  2. It then passes through the thermal store’s copper coil heat exchanger where it is heated further by the surrounding hot water from the primary system (the central heating system).
  3. The water then passes through a blending valve, where it is controlled to an optimum 30ºC before entering the boiler.


Due to the mains water being pre-heated, the boiler’s workload is significantly reduced. This provides up to a 25% gas saving when compared with a conventional boiler and hot water cylinder.

The FlowSmart system consists of either an InTec 34C combination boiler with separate GasSaver unit, or an InTec 40GS Plus integrated GasSaver boiler. It also includes a 50 litre thermal store, which can be supplied as a floor-standing unit or combined with the InTec 40GS Plus in an integrated wall-hung version.

To find out more about FlowSmart click here