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This article forms the basis of the literature on the ETHER HIU, for publication in August 2015.

Installation Instructions

ETHER Installation Instructions

DIGI Installation Instructions


The Ether HIU, Front View
The Ether HIU, Bottom View
The Ether

The ETHER HIU is one of the new generation of HIUs, using electronic stepper motor controls. It is primarily based on The DIGI HIU however it has been adapted to allow indirect connection to the properties heating system.

The ETHER is designed to deliver very low central heating loads under 5kW while maintaining low primary return temperatures. In addition the twin wall DHW heat exchanger provides complete protection from cross contamination in the case of a plate failure.

As an optional extra The ETHER can be fitted with an industrial 8 port Ethernet switch, to establish a LAN across the site for use by billing and monitoring services. This is to provide a lower cost and more robust alternative to using GSM mobile connectivity and the increased traffic capabilities enable high resolution remote monitoring to become an option, without incurring significant increases in data costs.

Ether 02.png



Pressure 10-20 kPa
Kvs value diff. pressure controller 2.5


Hot Water

Output 68kW
Pressure loss @ Max. Output 57 kPa
Capacity @ 10-55°C 21.5L/min
Temperature Range 45 to 60°C

District Heating Circuit

Max.flow temp. 90°C
Pressure class PN10
Minimum flow temperature 65°C
Max. differential pressure 250 kPa
Min. differential pressure 50 kPa
Max. pressure loss <25 kPa


  • Primary flow G3/4" BSP
  • Primary return G3/4" BSP
  • Central heating flow G1/2" BSP
  • Central heating return G3/4" BSP
  • Central heating discharge 15mm Copper Tail
  • Mains water feed G1/2" BSP
  • Domestic hot water outlet G1/2" BSP


Wiring Diagram

  • Connect Room Thermostat between terminals 2 and 3. If power is required to the room thermostat this can be taken from terminals 4 or 5.
  • Connect Mains power supply to terminals 5, 8 and 9.

Billing Network Wiring



The Ether HIU, Components
Item No. Pt.No. Description
1 Metal Backplate - Not available as a spare
2 Fixing Point - Not available as a spare
4 70HSF51237 DHW Plate heat exchanger
5 7066556 Heating Plate heat exchanger
6 70HSF53067 Primary Strainer
7 70HSF51495 Electronic stepper control valve
8 70HM402-1.5G34B-110F Kamstrup MC402 Heat Meter
9 Heat Meter Calculator - Not available as a spare
10 70HSFSP59214 Differential Pressure Control Valve Spare
11 7026187 Auto air vent with check valve
12 702320 Danfoss Direct Acting Solenoid
12a 702322 Terminal Block to suit Danfoss Solenoid Coils
12b 702321 Danfoss Solenoid Coil 230v
13 702323 Double Regulating Valve
14 70200226 Heating Pump
15 Pump Union - Not available as a spare
16 70200178 Expansion Vessel 5 Litre
17 7069560 Safety Relief Valve
18 70826 Drain Cock
19 70HSF52727 Temperature Sensor
20 70HSF51770 DIGI Full electronics - Control and Cables
20a 70HSF50274 Flow Sensor
21 Din Rail Terminals - Not available as a spare
22 70230514 Din Rail Power Supply
22a 70EKI-7710E-2CI 8FE+2G Port Gigabit Managed Ethernet Switch
23 Cable Glands - Not available as a spare
24 70RD00005 External Steel Casing

Note: A central heating filling loop is not provided within the HIU. This is to be provided by the installer in a location accessible to end user.

Installation of Heat Meter

Important Note: On the Digi HIU the Heat Meter is fitted on the flow.

  • Option 1: Standard Immersion Sensor
  • Option 2: 1/2" Pocket

Digi Heat Meter.jpg

Digi Heat Meter 2.jpg

Solenoid Security Valve

EV250B Solenoid

The Danfoss EV250B Solenoid Valve is used as a security isolation valve, to be wired to a billing system. The purpose of the valve is to close the primary supply on loss of credit, preventing further production of hot water and central heating, until allowed by the billing system.

EV250B with assisted lift can operate from zero and up to 10 bar differential pressure. This 2/2-way valve program is especially to use in closed circuits with low differential pressure, but demanding moderate flow rates. Valve body in dezincification resistant brass for ensuring a long life even in connection with aggressive steam media. EV250B is compatible with the broad Danfoss coil program with enclosures from IP00 up to IP67. Medium temperatures up to 140°C (low pressure steam).

  • For water, oil, compressed air and similar neutral media
  • Flow range: 0.5 - 20 m3/h
  • Differential pressure: 0 - 10 bar
  • Media temperature from -30 - 140 °C
  • Ambient temperature: Up to 80 °C
  • Coil enclosure: Up to IP67
  • Thread connections: From Gâ…œ - G1
  • DN 10 - 22
  • Viscosity: Up to 50 cst
  • The valve can be used for rough vacuum
  • Water hammer damped
  • DZR brass version in NC and NO

Ethernet Switch

ESW500 Ethernet Switch

The ESW500 range of Industrial Managed Ethernet Switches establish Ethernet network connections to multiple billing systems, or iHIU controllers.

Ethernet cables are limited to a maximum length of 90 metres. For establishing networks with distances of over 90 metres between switches, please refer to the options for the Ethernet Switch with Fibre Optic Connections.

  • 8 or 16 port options
  • Light industrial design EN61000-6-1 specifications
  • NEMA TS2 (ESW508-T)
  • Shock and vibration tested
  • -10 to 60°C or -40 to 75°C (-T models) temperature rating
  • Supports IEEE 802.3 10Base-T,802.3u 100Base-TX
  • RJ-45 port supports auto MDI/MDI-X function
  • SC single mode and multi mode fiber connectors
  • Gigabit options with copper and SFP combo ports
  • Web browser management and configuration
  • Ring On redundant rapid recovery system, 15 mS
  • Rapid spanning tree protocol recover system
  • IGMP with query mode for multimedia application
  • Port based VLAN / 802.1 Q Tag VLAN
  • Relay alarm output for system events
  • Port mirroring for diagnostics
  • 256K bytes packet buffer
  • 8k MAC address table

RingOn Technology

Two ports can be used for network redundancy by implementing RingOn technology providing a rapid recovery system for industrial networks. If any part of the ring disconnects the network communications will automatically be restored.

Web-based Management

Each switch has an embedded HTML web site residing in flash memory, offering advanced management features allowing users to manage the switch from anywhere on the network via a standard web browser.

VLAN Configuration

A Virtual LAN (VLAN) is a logical network grouping that limits the broadcast domain. This allows you to isolate network traffic so that members of a VLAN will only receive traffic from other members of the same VLAN.


Follow these steps for the commissioning of the HIU. In case of leaks or other abnormalities, please refer to the chapter on Fault Finding.

  • Close all water outlets in the house.
  • Check all nuts for tightness.
  • Make sure that the electronics housing is in place and the cables do not obstruct the cover when it is closed.
  • Slowly turn on the mains water supply and check the set for leaks.
  • Open the central heating isolating valves.
  • Check the air vent on the heating circuit within the HIU is not capped.
  • Connect the central heating filling loop (by installer) and fill the central heating circuit to 1.5 bar, checking for leaks.
  • Check both isolating valves are closed
  • Carefully remove caps, expecting some drips
  • Connect filling loop
  • Open the system side isolating valve fully
  • Open mains isolating valve slowly until the pressure on the gauge starts rising
  • When the pressure has reached 1.5 bar, close the mains isolating valve
  • Close the system isolating valve
  • Disconnect the filling loop, catching the water from within the hose
  • Replace the caps
  • Turn on power to the system. The LED should flash green.
  • Turn on power to the Billing System. There will need to be sufficient credit on the system to open the security valve and allow flow to the HIU for commissioning. Please contact the billing system provider for further assistance if required.
  • Slowly open the district heating supply and check the set for leaks.
  • Slowly open a hot water faucet. Check during this step continuously or the LED indicator (C) of the electronics blue flashes. Open the tap completely once all the air is out of the pipe and let it stand for 5 minutes open. Check between 3 and 5 minutes the water at 57°C - 60°C.
  • Close the water tap. The LED flashes green.
  • Turn on the central heating using the programmer and room thermostat (turned up) installed elsewhere in the property. The central heating pump will start to run, clearing air through pipework towards radiators.
  • Bleed the central heating system, keeping an eye on the system pressure. Start with lowest and finish at highest radiator.
  • Leave the central heating on for 5 minutes and confirm heat is supplied to radiators.
  • With the central heating on, check the primary flow rate using the heat meter display, and if required adjust the flow using the central heating regulating valve until the design flow for the property is achieved.
  • With the central heating on, record the following data from the heat meter on the commissioning sheet:
    • flow rate [m3/h]
    • primary flow temperature [°C]
    • primary return temperature [°C]
  • Turn off the central heating and record the following data from the heat meter on the commissioning sheet:
    • energy use to date [kWh]
    • model and part code
    • serial number
  • Where appropriate, check the figure for the energy use matches that provided on the billing system display.
  • Cap the automatic air vent for the central heating.
  • Fit internal HIU insulation cover, using the blue security washers provided.
  • Fit external HIU casing, and retain using security bolt.
  • Central heating circuits should be protected with a suitable corrosion inhibitor. The procedure for doing this will depend upon the type of inhibitor, with the most common method been to inject inhibitor via a radiator.

Maintenance and Servicing

Annual Checks

Central Heating Pressure

  • Check pressure in central heating system is between 1.2 bar and 2.5 bar.
  • Fill as required.
  • Check both isolating valves are closed
  • Carefully remove caps, expecting some drips
  • Connect filling loop
  • Open the system side isolating valve fully
  • Open mains isolating valve slowly until the pressure on the gauge starts rising
  • When the pressure has reached 1.5 bar, close the mains isolating valve
  • Close the system isolating valve
  • Disconnect the filling loop, catching the water from within the hose
  • Replace the caps


  • Isolate all connections.
  • Where a drain cock is provided drain water from HIU.
  • Using an adjustable spanner, loosen the cap from the strainer, being careful to catch any discharged water.
  • Remove the filter, clean and replace.
  • Replace cap, and tighten.
  • Repeat for all strainers (primary, mains, and central heating).
  • Open all isolating valves carefully, checking for leaks.

Every 5 Years

  • Recallibrate or Replace heat meter (must be performed by approved engineer)

Corrosion Inhibitor

Please refer to guidelines provided by the supplier of the chosen corrosion inhibitor as to the frequency and method of re-dosing the system. Always leave a record with system, typically using label provided with inhibitor.

User Guide


The Thermal Integration Ether is used to generate hot water and central heating from a heat distribution systems.

The HIU should be installed under the following conditions:

  • HIU should be installed degree in a frost-free area
  • HIU should not be exposed to direct sunlight.
  • Ambient temperature: 5°C to 40°C
  • Humidity range: 10% - 85%

LED Status Indicators

The system provides an LED indication of its current status.

  • Green flashing: Normal operation
  • Blue flashing: Tapping operation
  • Red flashing: Failure
  • White continues: Service mode (for installers only)
  • No light: Power is off


The differential pressure controller regulates the differential pressure across the heating system keeping it constant regardless of flow rate. This differential in pressure causes the flow of heat from the distribution network through the heating system. The heating system controls provided in the property determine how much heat is provided to each room.

The HIU is equipped with a copper brazed, double-walled plate heat exchanger. It is comprised of numerous plates of metal, through which heat is transferred from hotter water to colder water, with total hydraulic separation. A double-walled plate heat exchanger has an air gap between each of the hydraulic circuits so that in the event of a plate rupture, the hydraulic circuits remain separated to avoid the risk of contamination of the potable water.

Economy / Comfort Mode

It is common for HIUs to include a thermostatic bypass to maintain Domestic Hot Water temperatures at all times, and prevent delays in hot water supply. The ETHER performs a similar function, momentarily opening the Domestic Hot Water stepper motor slightly to allow small quantities of primary water to enter the unit at regular intervals. The ETHER will creep primary water into the unit ensuring that return temperatures remain below the Domestic Hot Water setpoint. The primary pipework usually loses heat faster than the ETHER's casing, hence the unit will typically settle trickling in heat fast enough to keep the primary flow at Domestic Hot Water temperature. The ETHER (DATA and DIGI) are the only HIU's capable of this level of control, ensuring low return temperatures at all times.

In addition, the ETHER provides an option that can be setup during commissioning to keep the Domestic Hot Water up to temperature continuously, or to allow it to go cold after 1 hour of inactivity. This option is desirable when the heat loss of the ETHER and its pipework is greater than the perceived down-side of a longer delay during the first morning, or evening draw-off.

The ETHER uses an electronically controlled valve and flow sensor. During hot water demand the flow sensor will detect the draw-off rate and convey this to the electronic control. This ensures optimum opening of the valve, thus obtaining a water temperature of 60°C.

While hot taps are running the system provides hot water priority, closing off the supply to the central heating. When tapping stops the heat supply resumed to the heating circuit.