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

Herz Armaturen GmbH Richard-Strauss-Str. 22, A - 1230 Vienna Tel.: +43 (0)1 616 26 31-0, Fax: +43 (0)1 616 26 31-27 E-Mail: office@herz.eu

Herz Valves UK Ltd. Progress House, Moorfield Point Moorfield Road, Slyfield Industrial Estate Guildford, Surrey GU1 1RU Tel: 01483 502211, Fax: 01483 502025 E-Mail: sales@herzvalves.com

www.herzvalves.com

Issue 0916

Page 2

Page 3

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 4

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.

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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.

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1.3 Layout of components

1.4 General

All union nuts must be tightened after installation and before filling to ensure no leaks have been caused through

transportation vibrations and heat expansion

No Description 1 DHW Heat Exchanger – Stainless Steel brazed

2 Pressure Temperature Control Valve

3 Thermostatic Head with contact sensor

4 Primary Flow Strainer

5 Primary Circulation Thermostatic Bypass Valve

6 Differential Pressure Control Valve

7 Optional Heat Meter or spacing piece

8 Optional Water Meter or spacing piece

9 Drain and Vent Valves

10 Primary Flow Isolation & Drain Valve with test point

11 Primary Return Isolation & Drain Valve with test point

12 DHW Outlet Isolation & Drain Valve

13 Mains Cold Isolation & Drain Valve

14 Insulated back board

15 Optional Heat Meter display bracket

9

3

1 2

5

7

4 8

6

11 10

14

12 13

15

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2.0 Installation Instructions

Pre-installation

Please ensure that drain cocks are fitted to the relevant pipework prior to the HIU being fitted to facilitate any

necessary filling and draining functions.

All pipes connected to the HIU must be insulated to prevent any thermal transfer.

2.1 Installation

Please be aware that this HIU can be installed with the ball valves at the top or bottom, the template must

be positioned on the wall the correct way up to suit the installation.

Please ensure the HIU back plate is level before fully securing to the wall.

Using the template supplied in the packaging, mark the wall for the hole positions ensuring that the plate is level and making sure there is enough clearance space above the HIU to allow for installation. Drill the holes for the HIU with a suitable drill. Secure the HIU to the wall using fixings suitable for the type of wall. Check the ball valve connections then fit the respective pipework to the ball valves and tighten the compression connections. If a flushing bypass is to be used, this should be fitted to the primary flow & return ball valves before the pipework is connected.

If the ball valves are to be installed at first fix before the HIU is fitted, an HIU should be used as a template to

work out the valve positions, then install as above.

If the ball valves have already been fitted, please ensure that the seals are fitted to the ball valve connections before connecting to the HIU. If the heat meter is installed, a bracket is supplied with the HIU for fitting the heat meter display to the top of the HIU (bottom entry) or the bottom of the HIU (top entry) if required. Screws are supplied to fit the display to the bracket and the bracket to the HIU.

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3.0 Commissioning

All union nuts must be tightened after installation and before filling The primary pipework must be flushed before any water can pass through the HIU. This can be facilitated with the Herz flushing bypass (available separately) connected to the primary flow and return ball valves. Failure to do so could invalidate the warranty.

3.1 Pre-commissioning The District heating primary circuit should be flushed and treated in accordance with the relevant standards and

regulations. Failure to do so could invalidate the warranty.

3.2 Filling and venting Open the ball valves slowly in the following order, taking care not to induce any water hammer. Slowly open the ball valve on the primary flow. Slowly open the ball valve on the primary return and release any air using the manual air vent. Slowly open the ball valve on the mains cold water inlet. Slowly open the ball valve on the domestic hot water outlet and open a hot tap for several minutes. Close the tap and release any air using the manual air vents. Please note: If the HIU is installed with the ball valves at the top and pipe entry from above, the drain valves fitted to the ball valves will operate as air vents.

3.3 Controlling the flow temperature of the domestic hot water The temperature of the DHW is controlled by the thermostatic head installed on the Pressure Temperature Control valve which is factory preset and should require no adjustment. We would recommend the use of TMV3 thermostatic mixing valves on terminal units to ensure temperature stability.

3.4 Testing Open a hot tap and take a temperature reading. Allow the water to continue flowing for several minutes and re check the temperature. If the temperature is too low or high, adjust the setting of the thermostatic mixing valve if fitted at the outlets. If fitted, check that the heat meter anti-tamper seals are intact.

Please ensure that all commissioning data is recorded on the check list supplied separately, one copy to be returned to Herz Valves UK Ltd and one copy to be left with the HIU. Failure to do so could invalidate the warranty.

3.5 Fitting the cover When all the commissioning is completed, fit the cover by aligning the four slots on the edge of the cover with the appropriate locating lugs on the HIU, push the cover in towards the wall and drop down into position. Fit the anti-tamper screw, supplied loose, to the threaded hole on the left hand side of the cover.

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4.0 Servicing 4.1 Draining down

CAUTION: Servicing should only be carried out by a Herz approved service engineer. CAUTION: The district heating side of the HIU can be operated with high pressure and temperature systems. Please apply extreme caution and wear the appropriate safety equipment (PPE) when working on suspected leaks.

Draining down the primary Close the primary flow and return ball valves and open the manual air vents to release the pressure. Open the drain valves on the primary flow and return ball valves carefully and drain into a suitable container.

Draining down the domestic hot water Close the mains cold water inlet ball valve and open a hot tap. Open the manual air vent positioned above the pressure temperature control valve. Open the drain valve on the mains cold water inlet ball valve carefully and drain into a suitable container. If the HIU is installed for top entry pipework with the ball valves at the top of the unit, the draining functions will be carried out with the two drain valves situated at the bottom of the unit and the drain valves fitted to the ball valves will be used as air vents.

4.2 Component servicing In hard water areas lime-scale can build up in the system. Depending on the hardness of the water, the unit should be de-scaled by a professional every one to two years. If lime-scale build up in the system is excessive some of the valves could be damaged, these should be replaced immediately to ensure reliable operation of the heating system. Do not clean the unit with scouring or harsh cleaning agents. Wipe it down with a damp cloth which has been rinsed in water with a few drops of mild detergent.

Domestic water Heat exchanger

Routine servicing – Check all connection seals, check all temperatures against the commissioning data and

change the heat exchanger if the DHW temperature is significantly reduced.

Component replacement – Drain the primary and domestic sides of the unit. Undo all 4 connections and

remove the heat exchanger. Replace the heat exchanger, refit the connection nuts replacing the seals.

Ball valves

Routine servicing – Operate valves regularly and check all connection seals.

Flow restrictor

Routine servicing – Located directly underneath the Pressure temperature control valve between the two

union nuts on the cold water feed. Check all connection seals and drain the domestic side of the unit. Undo the union nut on the cold water feed at the water meter spacing piece, undo the union nut at the double union on the pipe and remove the pipe, undo the union nut at the PTC valve connection to access the flow restrictor. The flow restrictor is now accessible inside the connection immediately below the inlet to the pressure temperature control valve. Remove the flow restrictor noting its flow direction, inspect for damage and debris, clean and refit into the connection pipe. Reassemble the pipework in reverse making sure that all connections are tightened correctly.

Component replacement – Same procedure as above replacing the flow restrictor with a new component.

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Pressure temperature control valve

Routine servicing – Check all connection seals, check central leakage hole which indicates the integrity of the

O rings sealing the domestic side from the heating side, remove thermostatic head and check the insert for leaks and action the insert drive pin.

Component replacement – Remove the thermostatic head, drain both the primary and domestic sides of the

unit. Undo all 4 connections then replace the valve. Refit the connection nuts replacing the seals taking care not to mix the top & bottom seals which are a different thickness. Refit the thermostatic head.

Thermostatic head with contact sensor

Routine servicing – not required

Component replacement – Drain the domestic hot water. Remove the allen screws from the bracket which

secures the contact sensor and lift clear. Undo the connection nut and remove the sensor probe also removing the thermostatic head from the valve. Refit the head and smear the contact sensor with silicone grease before inserting back into position. Then refit the connection nut having replaced the seal. Reposition the bracket over the contact sensor and replace the allen screws. Note the position of the locking pins fitted to the underside of the thermostatic head and ensure that the pins are fitted in exactly the same position on the replacement head. The two pins should be fitted at either end of the green line located between positions 2 and 3. Check the temperature of the DHW as per Section 3.4 Testing.

Thermostatic bypass valve

Routine servicing – Check all connection seals, remove the head, check the insert for leaks and action the insert

drive pin, replace insert if necessary. Remove valve before replacing the insert.

Primary flow strainer

Routine servicing – Check all connection seals, drain the primary, remove strainer cap and check strainer

basket.

Differential Pressure Control Valve

Routine servicing – Check all connection seals

Component replacement – Drain the primary, undo the capillary retaining nut and the union connection nuts

and replace the valve taking into account the flow direction arrow, then reconnect the capillary.

Heat meter (if fitted)

Routine servicing – Check all connection seals and check anti-tamper seals are intact

Component replacement – Drain the primary side of the unit. Remove the sensor from the strainer boss by

removing the securing pin and pulling the sensor out. Undo the 2 connection nuts and remove the meter from the pipework. Replace the meter taking into account the direction flow arrow and refit the connection nuts replacing the seals. Refit the sensor into the strainer boss and replace the securing pin taking care not to push it in too far. Fit anti-tamper seals to the sensor connections and display box if necessary (this may be done by the energy provider).

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4.3 Fault Location Table

Before attempting to locate faults on the Herz HIU please ensure the following:

The primary flow temperature is correct The primary flow rate is correct There is sufficient primary pump pressure to allow circulation through the Heat Exchangers

5.0 Technical data

The HIU is designed for maximum PN10 primary side working pressure Maximum district heating flow temperature is 90°C Minimum differential pressure between primary flow and return is 30kPa Minimum cold water pressure to the HIU is 2.5 bar

5.1 Appendices Operating data Function schematic Spare parts list Water quality parameter table Dimensional drawings

Problems with hot water

Long wait for hot water at the tap

Check the bypass circuit

Check the primary heating circuit

Pressure temperature controller is leaking

Replace the Pressure temperature controller

Pressure temperature controller sticks

Replace the Pressure temperature controller

Temperature of the hot water is too low

Increase the flow temperature on the heat source

Check the valves settings on the unit

Check/Clean the primary flow strainer

Check the settings on the primary heat pump

Check the heat exchanger and, if necessary, replace

Check the Pressure temperature controller and, if necessary replace

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5.1.1 Operating data

5.1.2 Function schematic and Description

Please note: all diagrams are indicative in nature and do not claim to be complete

The system comprises of a heat exchanger (1) and a Pressure Temperature (PT) control valve (2) which controls the operation and temperature of the DHW system. In the stand-by mode the heating primary water is kept at operating temperature via a thermostatic circulation bypass valve (5). When a hot tap is opened, the PT controller (1) reacts to the difference in pressure and opens the cold water inlet to the heat exchanger allowing hot water to flow through to the tap. The temperature of the hot water that exits the heat exchanger (1) is controlled by the thermostatic head (3) which regulates the PT controller (2).

Description Data Height 490mm (with ball valve cover 600mm)

Height with heat meter display 737mm

Width 400mm

Depth 160mm

Total unit weight 13.7kg

Total unit weight with cover 17.7kg (with ball valve cover 18.8kg)

Maximum DHW output 55kW (20 l/min) 42kW (15 l/min)

Maximum primary supply temperature 90°C

Maximum DHW temperature 55°C

Minimum DP 30kPa

Maximum working pressure primary side 10 bar

Maximum working pressure DHW side 10 bar

Ball valve connections 22mm compression (15mm adapter available)

No Description

1 DHW heat exchanger - Stainless Steel brazed

2 Pressure temperature control valve

3 Thermostatic head with contact sensor

4 Primary strainer 0.5mm mesh

5 Primary thermostatic circulation bypass valve

6 Differential pressure control valve

7 Optional heat meter

8 Optional water meter

9 Drain and vent valves

10 Isolation and drain ball valves with test points

11 Isolation and drain ball valves

Primary F&R MCW DHW

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5.1.3 Spare Parts List

9

7

11

13 10

8

5

6

1

14

2

10 12

3

4

Page 14

5.1.4 Water quality

Parameters Recommended limits for water quality

PH value 7 - 9

Alkalinity 60 mg/l < [HCO3 -] <300 mg/l

Electrical conductivity <500 µS/cm

Hardness [Ca2+,Mg2+]/[HCO3-] > 0.5

Chloride 1000 mg/l at 25 °C 300 mg/l at 50 °C 100 mg/l at 80 °C 0 mg/l at T > 100 °C

Sulphate [SO42-] < 100 mg/l and [HCO3 -]/[SO4

2-] >1

Nitrate [NO3 -] < 100 mg/l

Free chlorine < 0.5 mg/l

Note: The given reference values for the heat exchanger are dependent on the required water quality. Consideration should be given to the use of a scale prevention device when aggressive water supplies are present

No Description Part No Insert Seals Part No Qty

1 DHW Heat Exchanger 1401847 1402045 4

2 Pressure Temperature Control valve 1400800 1402046 + 1402047 2 of each

3 Thermostatic Head with contact sensor 1401965

3 Contact Sensor connection sealing nut 1401898

4 Strainer mesh 1401897

5 Primary Circulation Bypass Valve 1774691 1639091 1402045 + 1300101 2 of each

6 Return Temperature Limiter 1920102

7 Differential Pressure Control Valve 1400259 1402045 2

8 Optional Heat Meter 1402267 1402045 2

8 Heat meter probe connection nut 1402055

9 Drain Valve (red handle) 1027609

10 Drain Valve (green handle) 2027609

11 15 l/min Flow limiter 1402069

11 20 l/min Flow limiter 1402057

12 Manual Air Vent 1402059

13 Drain Valve (Red test point) 1028422

14 Drain Valve (Blue test point) 1028421

Seals Part No

Flat Sealing gaskets standard 1402045

Flat Sealing gaskets for PTC 2mm 1402046

Flat Sealing gaskets for PTC 3.4mm 1402047

Euro cone to flat sealing nipple 1300101

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5.1.5 Dimensional Drawings

Bottom entry version Top entry version

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All specifications and statements within this brochure are according to information available at the time of printing and meant for

informational purpose only. Herz Armaturen reserves the right to modify and change products as well as its technical specifications and/or

it functioning according to technological progress and requirements. It is understood that all images of Herz products are symbolic

representations and therefore may visually differ from the actual product. Colours may differ due to printing technology used. In case of any

further questions don’t hesitate to contact HERZ.