Herz OXFORD Installation, Maintenance & Operating Instructions

Herz Armaturen GmbH

Richard-Strauss-Str. 22, A - 1230 Vienna
Tel.: [phone], Fax: [phone]

E-Mail: [e-mail]

Herz Valves UK Ltd.

Progress House, Moorfield Point
Moorfield Road, Slyfield Industrial Estate
Guildford, Surrey GU1 1RU
Tel: [phone], Fax: [phone]
E-Mail: [e-mail]

www.herzvalves.com

Issue 0916

INSTALLATION, MAINTENANCE & OPERATING INSTRUCTIONS

FOR

HERZ OXFORD DOMESTIC HOT WATER

HEAT INTERFACE UNIT (HIU) 15 & 20l/min

Please note actual unit may vary from above picture

For service contact the installer or the Community Heating Maintenance Company

Contents

Page 2

Contents

1.0 General Page 4

1.1 Description, main features and function of the Herz Oxford HIU Page 4

1.2 Warnings Page 5

1.3 Layout and components Page 6

1.4 General Page 6

2.0 Installation Instructions Page 7

2.1 Installation Page 7

3.0 Commissioning Page 8

3.1 Pre-commissioning Page 8

3.2 System filling and air venting Page 8

3.3 Controlling the flow temperature of the domestic hot water Page 8

3.4 Testing Page 8

3.5 Fitting the cover Page 8

4.0 Servicing Information Page 9

4.1 Draining down Page 9

4.2 Component servicing Page 9 - 10

4.3 Fault location table Page 11

5.0 Technical data Page 11

5.1 Appendices Page 11

5.1.1 Operating data Page 12

5.1.2 Function schematic Page 12

5.1.3 Spare parts list Page 13 - 14

5.1.4 Water quality Page 14

5.1.5 Dimensional Drawings Page 15

Page 3

1.0 General

1.1 Description, main features and function of Herz Oxford Heat Interface Units

Description

The Herz Oxford Domestic Hot Water Heat Interface Unit (HIU) provides domestic hot water to properties that
are serviced from district heating or central boiler plants. The HIU comprises of a single heat exchanger providing
instant domestic hot water at a safe regulated temperature. The HIU is indirect so the primary heating circuit is
hydraulically separated from the property DHW by the plate heat exchanger.

Main Features

Provides domestic hot water to properties
Hydraulic system separation by means of a heat exchanger
Continuous primary heating flow enables a permanent supply when domestic hot water is required
Differential Pressure control valve fitted over the primary flow and return within the unit to protect the HIU

from high system pressure and to regulate flowrate

Thermostatic temperature control regulates the hot water temperature
Pressure Temperature Control Valve allows the DHW heat exchanger to operate on demand only
Thermostatic circulation bypass to maintain a minimum primary supply temperature at all times
Minimised risk of lime scale formation and legionella bacteria
Low return temperature in the primary maximises efficiency in the system
Optional heat meter with pulse output, wireless operation or M Bus output
Optional water meter with pulse output, wireless operation or M Bus output
Easy to install with minimal installation space required
HIU can be installed for top or bottom pipework entry
Drain valves fitted to facilitate easy draining for maintenance
Anti-tamper cover fixing available

Function

In the stand-by mode the heating water flows from the primary circuit (district heating main) via a thermostatic
circulation bypass which is kept at operating temperature by means of a thermostatic head in direct contact with
the primary circuit water. Thus heating water from the primary circuit is always and immediately available at the
heat exchanger at all times. If a hot water tap is opened the pressure temperature control valve reacts to the
difference in pressure and opens allowing the cold and primary heating water to flow through the heat
exchanger. The cold water is heated up instantly and flows through to the domestic hot water tap. The
temperature of the domestic hot water is controlled by a thermostat. Using an immersion sensor, this thermostat
controls the temperature of the hot water that exits the heat exchanger and regulates the pressure temperature
control valve.

Page 4

1.2 Warnings

 Do not lift or carry the HIU by its cover, care should be taken, when lifting the unit, not to damage any of

the components.

 The unit must be installed and connected by professional plumbing and heating engineers only.

 Only use original HERZ spare parts when maintaining the HIU.

 Check all connections for leakages prior to starting up the heating system.

 The user must not make any technical changes to the HIU. Otherwise HERZ will not assume liability for any

resulting damage.

 The heat meter and sensor probes (if installed) should be fitted with anti-tamper seals by the energy
provider. The HIU should not be used by the end user if the seals are not intact and should be reported to the
energy provider or building management company/landlord.

If the property is to be left unoccupied for a prolonged period, it is recommended that the HIU domestic
pipework is isolated and drained.

 Surfaces of individual components, connections and leaking water can be very hot and cause severe burns

and scalds. Before the start of any dismantling work the isolation valves must be closed and water drained

out. Out flowing water is likely to be hot and under high pressure. Take appropriate precautions.

If a fault occurs, please contact the installer. Do not attempt to carry out repairs yourself.

Packaging

The following points should be observed during unpacking:

Check the delivery immediately upon receipt for completeness and transport damage.
In the event of transport damage, the delivery should only be accepted conditionally.
Carefully unpack the unit taking care not to damage the contents, sharp implements should not be used.
Ensure that all packaging material is removed and the unit is clean from all materials to avoid anything

preventing the unit from operating correctly.

Do not use damaged components for assembly.

Recycling and Disposal

The HIU as well as the packaging are mainly made of recyclable raw material.

The HIU and accessories should be disposed of sensibly and properly and not in household waste.
Disposal of the packaging is the contractor’s responsibility.

Page 5