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Unrivalled performance Our pioneering technology and control systems deliver high precision heat management and unrivalled performance in both domestic and district heating environments.

Best for through-life costs Intelligent design leads to greater simplicity – that’s why our systems are cost effective to install, more reliable and cheaper to run and operate.

Better by design Our unique and innovative technology has been refined over many years and is protected by numerous patents relating to water storage, heat exchange and the networking of communal heating systems.

The Amazon HX-HIU combines any of our single or twin plate HIU’s with an Amazon unvented hot water storage cylinder sized to your specific needs.  This means you can still take advantage of the highly efficient HIU technology, whilst charging a hot water cylinder from the district heating network.

The combination of systems provides the benefits of both, whilst overcoming the
disadvantages of both:-

  • Domestic hot water up to 50 litres per minute – equivalent to over 150kW.
  • Minimal draw from primary heat network, typically requiring no additional flow rate than that required for central heating.
  • The ability to weather compensate heat network below DHW temperatures, ramping up periodically for recovery.
  • High primary temperature drop on domestic hot water recovery, with return temperature typically lower than 30°C at all times.
  • Return temperatures under 30°C enable the use of heat pumps, waste heat, and will guarantee condensing operation of gas boilers.
  • Electric backup of hot water for occasions when the heat network is offline.
  • Variable storage volumes, with the ability to heat up either a full cylinder, half a cylinder, or just a sink full.
  • Instantaneous hot water provision, even when cylinder is cold.
  • The volume of storage is optional – so sites with varying load requirements can mix HIU’s on their own, and HIU’s with Amazon storage for higher loads.
  • Heating temperature control via the HIU allows connection directly to an underfloor heating system without the need for blending down the flow temperature at
    the underfloor heating manifolds.
  • When carrying out a refurbishment, it is also possible to connect one of our HIU’s to an existing unvented cylinder which saves money, and frees up the cylinder coil for other heat inputs such as solar thermal.
Note: This system is supplied as a kit of parts including the HIU, Cylinder, Pump(s), Control box and various fittings, for on-site installation, it is not a pre-plumbed cylinder.


HIU Type Heating and Stored Hot Water
Hot Water Configuration Indirect
Heating Configuration Indirect
Heating Temperature Control Yes
Built-in Heat Meter Yes
Dimensions Depends on HIU and Cylinder combination
Heating Output (nominal) 20kW
Hot Water Output (nominal) Up to 150kW / 65kW Instantaneous
Sealed System Kit Position Depends on the HIU

Note: The above image is representative of the DATA Twin plate HIU with an Amazon Cylinder and DHW recirculation.


  • Choose from any one of our Amazon cylinder sizes, from 125 to 500 Ltrs
  • Choose from the DATA, SPLIT, DIGI or SLIM ranges of HIU’s.
  • DHW Recirculation pump kit
  • Primary Shunt pump


Amazon HX-DATA Datasheet  Amazon HX-SPLIT Datasheet

Amazon HX-DIGI Datasheet  Amazon HX-SLIM Datasheet


Technical Detail


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