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Tank-in-tank products

Custom-made, fully insulated OEM tank-in-tank products with sensor pockets and heating coil connections in the side of the cylinder, makes these units the perfect companion for our customers’ heat pump. The units’ unique construction (pat.) provides optimal working conditions for heat pumps up to 12kW with the possibility of prioritizing domestic hot water (DHW) production. Integrated buffer tank functions as energy storage for space heating requirements. The tank-in-tank design provides consistent space heating temperature while DHW usage is high.


The unique tank-in-tank construction provides optimal working conditions for heat pumps up to 12 kW. The large buffer tank (> 100 l.) is suitable for space heating such as under-floor heating or wall mounted radiators. The water in the buffer tank transfers heat to the domestic hot water tank. This reduces return temperature to the heat pump and maximizes COP. There is no heat transfer from the DHW to the buffer tank due to carefully designed features. Should the heat pump fail, there is full electric back up through the 15 kW electric heater.

Once there is domestic hot water use, the variable valve in the heat pump switches its flow into the 1,8m² heating coil in the DHW tank, providing maximum heat transfer and domestic hot water production. During this time, the buffer vessel continues to provide consistent temperature to the space heating system, without compromising performance. The 3kW immersion heater heats the water up to 70°C. Separate ½” sensor pockets for precise control from the energy source is factory fitted. Low heat loss is provided by ECO Foam, with impressive key figures for GWP of 1 (Global Warming Potential) and ODP of 1 (Ozone Depletion Potential.)


Customer specified connection sizes / placements / electric heating and heating coil size are also available. For the perfect tank-in-tank cylinder, look no further.

Key advantages:

  • The ultimate tank-in-tank unit for heat pumps up to 12kW, providing both DHW & space heating
  • Unsurpassed energy efficiency with minimum heat loss and maximized COP
  • Impressive DHW production compared to traditional tank-in-tank units
  • 10 year warranty on the stainless steel inner cylinder & ECO Foam insulation
Multiple Energy Sources