Heat Interface Units (HIUs)

Cutting-edge, cost-effective Heat Interface Units from Dutypoint Systems

The Dutypoint range of Heat Interface Units (HIUs) provide a highly efficient and reliable solution for delivering renewable energy to apartment complexes. Hot water produced by a centralised district heating plant is transferred via integral heat exchangers to provide on-demand domestic hot water, and heating is provided with either a direct or indirect connection to the central system. Units are available with either thermostatic or hydrothermic control.

Advanced automated manufacturing technology enables us to offer specially configured heat interface units for each project. Units can be specified for conventional radiator systems or under-floor heating, with water and heat metering and wireless communication, as well as a number of enclosure configurations to suit the space available in the installation.

Element heat interface units - Discontinued

Dutypoint Element Heat Interface Units (HIU) are a high-quality solution for projects in which a centralised heating plant services multiple dwellings. A unique modular design allows specifiers to configure a unit which is exactly
suited to the installation.

A choice of heat exchangers can be selected for the space heating and domestic hot water capacity individually, and additional options such as first fix rails, zone valves, metering and additional communication protocols can be incorporated without significantly affecting the overall cost.

This flexibility, combined with high quality, high efficiency components allows the creation of a system which is efficient by design and ultra reliable.


  • WRAS approved for use with potable water
  • Energy-efficient design with low pressure loss and low standby heat loss
  • Reduced scaling of plate heat exchanger due to ribbed plates
  • Proportional flow controller offers fast response and rapid hot water delivery
  • Easy to install, commission and service, with a standard layout and many parts shared across the range
  • Flexible options for metering, billing and management
  • Flushing bypass to isolate the HIU from the primary system during flushing procedures
  • ‘ Keep warm’ function for fast delivery of hot water when required by the user
  • Insulated plate heat exchangers to minimise heat losses
  • Thermostatic mixing valve regulates the domestic hot water temperature to a maximum value, preventing overheating
  • Hot water priority function on larger units temporarily shuts off the heating and diverts all energy to hot water production
  • Filling loop included as standard
  • First fix rail for pre-plumbing
  • Integrated heat meter
  • Integrated water meter
  • M-Bus and similar data logging protocols with wireless or wired system for data collection
  • Remotely managed shut-off valve
Heat Interface Units 28HIU29- Product Overview


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Standard Technical Features

  • Hydraulic separation between the primary and secondary systems, with heating and DHW provided on-demand
  • High efficiency A-rated variable speed circulator pump to minimise energy consumption
  • Large 12 litre expansion vessel
  • Stainless steel insulated pipework to prevent corrosion
  • Integral flow limiter and strainers to prevent damage from suspended particles
  • Pressure tested prior to dispatch with all parts fitted to minimise onsite installation time
  • Two high-efficiency, enlarged plate heat exchangers to allow rapid, efficient heat transfer
  • Choice of top or bottom connections for either radiator or under-floor heating
  • Ecodesign 2015 ready


  • Option of thermostatic or hydraulic proportional control
  • First fix connection rail to allow pre-plumbing prior to installation of the unit
  • Water meter
  • Ultrasonic heat meter
  • Room sensor
  • External temperature compensation control
  • Flushing bypass
  • Wireless metering
  • Lacquered steel cover
  • Insulated heat exchangers

Standard Models


Domestic hot water capacity Up to 65kW*
Heating capacity Up to 20kW*
Maximum working pressure (primary) 10 Bar
Maximum working pressure (secondary, heating) 3 Bar
Maximum working pressure (secondary, DHW) 2 Bar
Maximum working temperature 95°C
Expansion vessel 12 litres
Connections ¾" BSP
Electrical supply 230/1/50

*Higher capacity units are available on request


Plate heat exchanger

Plates: High grade AISI 316 stainless steel

Soldering material: pure copper

Differential pressure controller

Body: brass

Spring: stainless steel

Seals: EPDM

Membrane: EPDM, stainless steel

Impulse tube: copper

Safety valve

Body: brass

Membrane: NBR

Pipework High grade AISI 316 stainless steel


Standard dimensions

Raditor heatingUnderfloor heating

Below is a selection of documents relating to this product range. Any downloads which relate to individual product models, including dimensional drawings, are found in the 'Variants / CAD' tab.


    Dutypoint Heat Interface Unit Brochure File Size: 231 kB

    Sales brochure for the Dutypoint Heat Interface Unit range


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