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HiFlow - 70HF-16987-40-31.jpg


The HiFlow HIU is a Single plate high output HIU designed to cater for your larger central heating or hot water requirements. These are available as individual units, but can also be frame mounted with several other HiFlow modules to create a modular substation. Please refer to our article on The Cupboard HIU

Each module is built into an Expanded Polypropylene (EPP) casing, which provides fantastic insulation properties. The plate heat exchanger and pipework is insulated within this casing, to minimise heat loss as much as possible.

Each HiFlow is fitted with our latest Heatweb BEMS Controller, together with a pressure independent control valve and Modbus enabled actuator. This enables the output of the HIU to be controlled based on feedback from several NTC sensors mounted on to the pipework. The controller can also be fitted with a GSM/GPRS 4G Dongle, which enables communication with the HIU over the internet.

The HiFlow can be fitted with a pump and safety relief valves for Central heating applications, and all DHW models are fitted with a flow sensor to enable the output of the unit to be controlled based on temperature and flow rate.

Documents & Links


Each HiFlow is fitted with our latest Heatweb BEMS Controller. As standard the HIU also has the capability of Modbus output for connection to a BMS, or the HIU can be used as a stand-alone unit with access to the HIU settings via a hardwired ethernet connection of GSM/GPRS Modem.

All HIU's are factory programmed with standard settings which enables them to work out of the box, however if you have specific settings that you require, please request a form from us, for you to fill in your required setting.

Default Settings - HiFlow CH

Setting Value
Heating Flow Temp. 60°C
Pump Over-run 55 Sec
Return Limit Enabled No
Return Limit Temp. N/A
Approach Temp.* 3°C
  • Approach Temperature refers to the heating flow temperature tracking the primary flow temperature. For instance if the primary flow temperature is lower than the heating flow temperature setpoint, the heating flow temperature will track the primary flow temperature by T-3°C.

Technical Data

Description Units Value
Height mm 665
Width mm 665
Depth mm 313
Weight (excl. mounting bracket) kg <30
Position Primaries & Secondaries bottom.
Primary Connections 1” BSP Female
CH supply 1” BSP Female
CH Return 1” BSP Female
Safety Relief Valve 15mm Copper Pipe
Primary Circuit
Maximum Supply Temperature ˚C 85
Minimum Supply Temperature ˚C 30
Pressure Class PN 16
Maximal Permissible Differential Pressure* kPa 400
Minimal Permissible Differential Pressure kPa 20
Max.flow l/h 3200
Primary Circuit
Pressure Loss kPa 20-60
Secondary Circuit CH
Max. output kW 100
Pump (Energy Class A) 15-70; 130
Pressure Relief Valve bar 3
Maximum Flow Rate l/h 1700
Additional Features
Casing Material EPP (Expanded Polypropylene)
Maximum Heat Losses W 50 (1.2 kWh/day)
Electrical Information
Electrical Supply Info 230V 50Hz
Fuse Ratings 3 Amp
Sensor CH NTC 10kOhm @ 25 Degrees

Parts I/D

HiFlow CH + Pump Parts.jpg
Item Description
1 Primary 'Y' pattern strainer
2 CH Flow temperature sensor
3 Primary Flow temperature sensor
4 Primary Flow control actuator
5 Primary Flow control valve
6 Plate heat exchanger
7 Primary Manual air vent
8 CH Automatic air vent
9 HIU Controller
10 CH 'Y' pattern strainer
11 Primary Return temperature sensor
12 CH Pump
13 CH Pressure gauge
14 3 Bar safety relief valve

Wiring Diagram

70HF-16987 Control Wiringjpg.jpg

70HF-16987 Control Wiringjpg.jpg

Wiring Diagram for the HiFlow CH HIU
Printable Wiring diagram


HiFlow CH + Pump Schematic.jpg


HiFlow Dimensions.jpg

No clearance is required either side of the HiFlow, however we recommend a minimum of 300mm above and below the unit.


Mounting the unit

The HIU is supplied with 4 holes drilled in the back plate, allowing it to be screwed to the wall using the relevant screws and washers for the wall construction.

Ideally the wall should be of solid construction, or it should be reinforced with timber or steel braces to take the weight of the HIU.