Atag iSteel Series User manual

iSteel
INSTALLATION MANUAL
ISSUE 2015 – V1
FOR MORE INFORMATION GO TO:
www.atagheating.co.uk

INTRODUCTION
The corrosion resistant iSteel Un ented cylinder is made from Duplex Stainless Steel. It is highly insulated with
en ironmentally friendly foam enclosed in a rust resistant white steel case.
It is a ailable in Direct, and Indirect ersions in a family of 7 sizes from 90 - 300 litres. Twin Coil Indirect units are a ailable
in 5 sizes from 150 - 300 litres. There is also a range of slim-style units from 60 - 210 litres again in Direct and Indirect
ersions, please contact ATAG Heating Technology about slim-style units.
To help ensure compliance with the rele ant Water and Building Regulations all iSteel units are supplied complete with
the necessary safety and control de ices needed to connect to the cold water mains. In order to ensure high flow-rate
performance with minimum pressure drop e en in lower pressure areas, pre-set high quality controls ha e been selected.
iSteel is appro ed to demonstrate compliance with Water Regulations and Building Regulations G3 & Part L.
STORAGE PRIOR TO INSTALLATION
iSteel should be stored upright in a dry area and kept in its original packaging until immediately prior to installation.
INSTALLATION PREREQUISITES
This Cylinder should only be installed by a competent installer holding their G3 un ented qualification. The installation of
this product is also notifiable under the national Building Regulations.
ONCE COMPLETED T IS INSTRUCTION MANUAL IN ITS ENTIRETY S OULD BE LEFT WIT T E OME OWNER.
W AT IS BENC MARK?
Benchmark places responsibilities on both manufacturers and installers. The purpose is to ensure that customers are
pro ided with the correct equipment for their needs, that it is installed, commissioned and ser iced in accordance with
the manufacturer’s instructions by competent persons and that it meets the requirements of the appropriate Building
Regulations. The Benchmark Checklist can be used to demonstrate compliance with Building Regulations and should be
pro ided to the customer for future reference.
Installers are required to carry out installation, commissioning and ser icing work in accordance with the Benchmark
Code of Practice which is a ailable from the Heating and Hotwater Industry Council who manage and promote the
scheme. Visit
www.centralheating.co.uk
COLD INLET SET – W AT ARE T E CONNECTIONS?
EQUIPMENT SUPPLIED WIT T E CYLINDER
Cold Wa
ter Inlet Set
LOOSE
15 x 22mm Tundish
LOOSE
Temperature & Pressure Relief Val e
FITTED
Expansion Vessel
LOOSE
Expansion Vessel Bracket
LOOSE
Compression Nut Connection For Expansion Vessel
LOOSE
Immersion Heater(s)
-
dependant on size and configurati
on
LOOSE
Instruction Manual
LOOSE
Benchmark Log Book
–
at
the rear of this manual
LOOSE
WATER SUPPLY

iSteel is capable of deli ering o er 50 litres per minute when connected to a suitable mains supply. The high quality inlet
control set with its 3 bar operating pressure has been designed to make the most of what is a ailable howe er the
performance of any un ented system is only as good as the water supply.
In un ented systems both hot and cold ser ices are supplied simultaneously from the mains so the maximum possible
on-site water demand must be assessed and the water supply should be tested to ensure it can meet these requirements.
If necessary consult the local water supplier regarding the likely pressure and flow rate a ailability.
It is important that site pressure readings are taken under dynamic flow conditions, high pressures under zero flow
conditions are not necessarily indicati e of satisfactory performance. A minimum of 1.5 bar at 20 l/m flow should be
a ailable. Where mains inlet pressures are likely to exceed 16 bar then an additional upstream pressure reducing de ice
should be fitted.
A minimum of 22mm supply pipe-work should ideally be pro ided and existing 1/2” (15mm) cold mains pipe-work may
need to be upgraded. Hard water treatment should be considered in areas where content it greater than 200ppm, if
required adjust cylinder temperature to below 60 degrees.
SITING T E UNIT
iSteel can be positioned more or less anywhere in the dwelling but it should be remembered that for e ery 1 metre that
an outlet is abo e the iSteel, the pressure will be reduced by 0.1 bar. If siting outside the heated en elope of the dwelling
such as in a garage or outbuilding then frost protection should be pro ided and exposed pipework should be insulated.
iSteel must be supported on a flat base capable of supporting the weight of the cylinder when full. The minimum
recommended cupboard size is 650mm square.
It’s important that consideration is gi en to access for maintenance of the al es. The immersion heaters are 375 mm
long and access space should be pro ided for possible future replacement, also adequate access to remo e and re-install
the cylinder in the e ent of a problem.
SC EMATIC

GENERAL INSTALLATION
COLD MAINS PIPEWORK
Run the cold main through the building to the place where the iSteel is to be installed. Take care not to run the cold pipe
near hot water or heating pipe work so that the heat pick up is minimised. Identify the cold water supply pipe and fit an
isolating al e (not supplied).
A 22mm BS1010 stopcock can typically be used but a 22mm quarter turn full bore al e would be better as it does not
restrict the flow as much. Do not use “screwdri er slot” or similar al es.
Make the connection to the cold feed of the cylinder and incorporate a drain al e. Position the inlet control just ABOVE
the Temperature & Pressure Relief Val e (TPRV) mounted on the side of the cylinder. This ensures that the cylinder does
not ha e to be drained down in order to ser ice the inlet control set. Ensure that the arrow points in the direction of the
water flow.
Select a suitable position for the expansion essel. Mount it to the wall using the bracket pro ided. Use the compression
connection supplied to connect the essel into the cold water pipe adjacent to the cold feed point on the cylinder. There
must be no obstruction or flow restriction between the cylinder and the expansion essel.
BALANCED COLD CONNECTION
If there are to be showers, bidets or mono-bloc taps in the installation then a balanced cold supply is necessary. There is
a 22mm balanced connection on the inlet control set. All outlets in the house will be at 3 bar and thus automatically
balanced.
OT WATER PIPEWORK
Run the first part of the hot water distribution pipework in 22mm. This can be reduced to 15mm and 10mm as appropriate
for the type of tap etc. Your aim should be to reduce the olume of the hot draw off pipework to a practical minimum so
that the time taken for the hot water is as quick as possible.
Do not use mono-bloc mixer tap or showers if the balanced cold connection is not pro ided, the unit will back pressurise
and result in discharge. Ensure that the top of the essel is accessible for ser icing.
PRIMARY COIL CONNECTIONS (INDIRECT ONLY)
Compression connections are pro ided for the primary circuit which must be positi ely pumped. Primary flow and return
connections are interchangeable to suit site conditions without affecting reheat times. These connections are metric and
should be changed by the installer if using Irish size copper tube.
Sealed or ented primary circuits can be used, to comply with normal installation practice the primary pressure should
not exceed 3 bar although the coil in the iSteel is suitable for up to 7 bar if required. The boiler may be Gas, Electric, and
Oil etc. but must be under effecti e thermostatic control. Uncontrolled heat sources such as some AGA’s, back boilers,
solid fuel sto es, etc. may not be suitable please contact us for guidance. The two port zone al e should be installed into
the primary flow pipework leading to the coil flow inlet. The direction of flow arrow should be towards the primary flow
connection. On twin coil cylinders an extra thermostat boss is pro ided.
SECONDARY CIRCULATION
Where secondary circulation is required a circulator suitable for potable water should be used in conjunction with a non-
return al e to pre ent backflow. It may be necessary to incorporate an extra expansion essel into the circuit to
accommodate the increased system water olume in larger secondary circulation systems. Where off peak electrical
tariffs are being used then secondary circulation should be a oided. A secondary return boss is fitted as standard on 210,
250 & 300L. On smaller sizes tee into the cold feed pipe abo e the drain.
IMMERSION EATERS
As a requirement of Building Regulations the iSteel immersion heaters are fitted with thermal cut-out in addition to the
normal control thermostat. To help ensure correct replacement the immersion heaters ha e a special 1¾" thread. They
are of a low noise Incoloy construction and rated at 3 kW at 240 V. Replacement immersion heaters should be purchased
ia oursel es otherwise your guarantee may be affected. For commercial / hea y duty installations where constant usage
/ reheat is required Titanium immersion heaters must be fitted in order to comply with the warranty.
The ‘O’- ring on the head of the immersion heater should be correctly positioned and lubricated before fitting. Screw in
hand-tight until almost sealed then gently tighten as the ‘O’ rings will seal easily. The electrical supply to each immersion
heater/s must be fused at 13A ia a double pole isolating switch to BS 3456. The cable must be 2.5mm
2
heat resistant
(85°C HOFR) sheathed flex complying to BS 6141:1981 Table 8. Do not operate the immersion heater/s until the unit is
full of water. If any sterilisation liquid is in the cylinder do not operate the immersion heater/s as this will cause premature
failure. Electric to be supplied by a fused supply compliant with local regulations, and fitted by a qualified Part P
Electrician.

ENERGY CUT OUT AND CYLINDER T ERMOSTAT (INDIRECT ONLY)
As a requirement of Building Regulations the iSteel units are fitted with a thermal cut-out in addition to the normal control
thermostat. This unit should be fitted to the dedicated boss on the cylinder and wired to the two port al e controlling
the primary flow (see wiring diagram).
DISC ARGE ARRANGEMENT
This guidance is a ailable as a download of the G3 Appro ed Document from www.planningportal.go .uk.
The discharge from both the temperature relief and expansion relief al es can be joined together ia a 15mm end feed
tee.
It is important that any discharge water does not collect in this pipe-work and can run freely to the tundish.
The tundish should be mounted in a ertical and isible position located in the same space as the un ented hot water
storage system and be fitted as close as possible and within 600mm of the safety de ice e.g. the temperature relief al e.
The discharge pipe-work from the tundish must be routed in accordance with Part G3 of the Building Regulations.
The discharge pipe from the tundish should terminate in a safe place where there is no risk to persons in the icinity of
the discharge, be of metal and:
•Be at least one pipe size larger than the nominal outlet size of the safety de ice unless its total equi alent hydraulic
resistance exceeds that of a straight pipe 9m long i.e. discharge pipes between 9m and 18m equi alent resistance
length should be at least two sizes larger than the nominal outlet size of the safety de ice, between 18 and 27m
at least 3 sizes larger, and so on. Bends must be taken into account in calculating the flow resistance. An alternati e
approach for sizing discharge pipes would be to follow BS6700 Specification for design installation, testing and
maintenance of ser ices supplying water for domestic use within buildings and their curtilages.
•Ha e a ertical section of pipe at least 300mm long, below the tundish before any elbows or bends in the pipework.
•Be installed with a continuous fall.
•It is preferable for the discharge to be isible at both the tundish and the final point of discharge but where this is
not possible or practically difficult there should be clear isibility at one or other of these locations.
Examples of acceptable discharge arrangements are:
1. Ideally below the fixed grating and abo e the water seal in a trapped gulley.
2. Downward discharges at a low le el; i.e. up to 100mm abo e external surfaces such as car parks, hard standings,
grassed areas etc. are acceptable pro iding that where children play or otherwise come into contact with
discharges, a wire cage or similar guard is positioned to pre ent contact whilst maintaining isibility.
3. Discharges at a high le el; e.g. in to metal hopper and metal down pipe with the end of the discharge pipe clearly
isible (tundish isible or not) or onto a roof capable of withstanding high temperature discharges of water and
3m from any plastic guttering systems that would collect such discharges (tundish a ailable).
4. Where a single pipe ser es a number of discharges, such as in blocks of flats, the number ser ed should be limited
to not more than 6 systems so that any installation can be traced reasonably easily. The single common discharge
pipe should be at least one pipe size larger than the largest indi idual discharge pipe to be connected. If un ented
hot water storage systems are installed where discharges from safety de ices may not be apparent i.e. in dwellings
occupied by blind, infirm or disabled people, consideration should be gi en to the installation of an electronically
operated de ice to warn when discharge takes place.
Any queries with regard to discharge arrangement contact your local council planning office.
600
mm Max

TWIN COIL FORMAT
Indirect twin coil units can be installed in two separate formats:
•In a solar powered system with a backup boiler.
•In a system with two non-solar heat sources (normally two boilers).
With either format it is essential that the installation meets all current regulations including, in particular, the high limit
cut out requirements of Building Regulation G3.
UPPER COIL
This is connected to the boiler as per the instructions for a iSteel single coil cylinder with the high limit thermostat inserted
into the middle thermostat pocket and wired to control the supplied two port al e in either the primary flow or return
as indicated in the wiring instructions.
LOWER COIL – SOLAR VARIENT
In a solar system the lower coil is connected to the solar heat source. Either primary coil connection may be used for flow
or return. The solar cylinder sensor supplied is inserted into the lower thermostat pocket and the energy cut out into the
upper pocket. The ‘mechanical’ control thermostat is not normally utilised in a solar system. In systems where the panels
are abo e the cylinder then the energy cut out shall be wired so as to interrupt the power supply to the solar pump or
controller in the e ent of o er temperature.
In systems where the cylinder is abo e the panels then the energy cut out should be wired to a suitable two port al e
(not supplied) on the return pipe-work to the solar panel.
LOWER COIL – NON SOLAR VARIENT
This is connected to the additional boiler as per the instructions for a iSteel single coil cylinder with the high limit
thermostat inserted into the lower thermostat pocket and wired to control the supplied two port al e in either the
primary flow or return.

WIRING DIAGRAM 2 X 2 PORT ZONE VALVES (TYPICALLY ONEYWELL “S” PLAN)
WIRING DIAGRAM 3 PORT + 2 PORT ZONE VALVES (TYPICALLY ONEYWELL “Y” PLAN)
O
G/Y
G/Y
Br
G
Bl
C
E
2
C
E
2
1
Br
G
Bl
O
1
2
3
4
5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
1
2
3
E
L=Li e, N=Neutral, C=Common, SL=Switched Li e, E=Earth
O
G/Y
G/Y
W
G
Bl
C
E
2
C
E
2
L
1
Br
G
Bl
O
1
2
3
4
5
6
N
3 Port
Mid Position
E
HTG
ON
DHW
ON
DHW
OFF
L
N
E
SL
1
2
3
1
2
3
L
N
E
N
L
N
E
2
3
2 Port (Heating)
Cutout
(combined) Duostat
2 Port (DHW)
PUMP
Wiring Centre
Room Stat
Programmer
Boiler
G=Grey, Bl=Blue, O=Orange, G/Y=Green/Yellow, Br=Brown
7
8
9
10
1
2
3
4
5
6
7
8
9
10
1
2
3
E
L
N
E
HTG
ON
DHW
ON
DHW
OFF
L
N
E
SL
2
3
1
2
3
L
N
E
N
L
N
E
2
3
Cutout (combined) Duostat
2 Port (DHW)
PUMP
Wiring Centre
Room Stat
Programmer
Boiler
W= White, G=Grey, Bl=Blue, O=Orange, G/Y=Green/Yellow, Br=Brown
L=Li e, N=Neutral, C=Common, SL=Switched Li e, E=Earth

COMMISSIONING SERVICING
FILLING
Check all connections for water tightness including any factory made connections such as the temperature and pressure
relief al e. The pressure in the expansion essel should be checked to ensure it is 3 bar (45PSI). The al e is of the car
tyre (Schrader) type.
The hot tap furthest away from the iSteel should be opened before filling the system to let air out.
The system should be flushed before use. The remaining taps should be opened in turn to expel air.
DIRECT UNITS
The system must be fully filled and flushed before switching on the power to the immersion heaters and allowing the
unit to heat up. The immersion heater is supplied pre-set at 55°C. Turning fully to + sets to approx. 65°C.
INDIRECT UNITS
Ensure the le er on the two port al e is set to the filling position and use the boiler manufacturers commissioning
instructions to fill the primary circuit. When full release the le er. Switch the programmer to Domestic Hot water (DHW)
and allow the unit to start to heat. Adjust the dial of the dual thermostat to between 55°C and 65°C as required.
STORAGE TEMPERATURE
A storage temperature of 60-65°C is normal for both direct and indirect iSteel. In hard water areas consideration should
be gi en to reducing this to 55-60°C. In many healthcare applications the guidance on Legionella control and safe water
deli ery temperatures will require storing the water at 60-65°C, distributing at 50-55°C and using thermostatic mixing
al es to control the final temperature. For details consult the NHS estates guidance on safe hot water temperatures.
SAFETY VALVE C ECKS
Any water coming from either the expansion relief al e or the temperature / pressure relief al e during heat up is
indicati e of a problem which needs to be identified and rectified. The temperature relief and expansion relief al es
should be fully opened, one at a time then both together allowing as much water as possible to flow through the tundish.
Check that your discharge pipework is free from debris and is carrying the water away without spillage o er the tundish
and release the al es and check that they re-seat properly.
GENERAL
Ser icing should only be carried out by competent installers and any spare parts used must be purchased from ATAG
Heating Technology UK Ltd. NEVER bypass any safety de ices or operate the unit without them fully operational.
DRAINING
Isolate from the electrical supply to pre ent the immersion heaters burning out. Isolate the unit from the cold mains.
Attach a hose to the draining tap ensuring it reaches to a le el below the unit (This will ensure an efficient syphon is set
up and the maximum amount of water is drained from the unit). Open the hot tap closest to the unit and open the
draining tap.
WARNING: WATER DRAINED OFF MAY BE VERY OT!
ANNUAL SERVICING
A competent installer should carry out the following checks on an annual basis, ideally at the same time as the annual
boiler ser ice.
1. The expansion relief al e on the inlet control set should be eased open allowing water to flow for 5 seconds. The
al e should then be closed making sure it resets correctly. Repeat this procedure with the pressure / temperature
relief al e. Always insure that the discharge pipework is allowing the water to drain away adequately. If not check
for blockages etc. and clear.
WARNING: T E WATER DISC ARGED MAY BE VERY OT!
2. Ensure that any immersion heaters that are fitted are working correctly and that they are controlling the water at
a temperature of between 55°C and 65°C.
3. Make sure the pressure in the expansion essel is charged to 3 bar. Turn off the water supply to the unit and open
a hot tap first. The al e on the expansion essel is a Schrader (standard car tyre) type. Air or CO2 can be used to
re-pressurise the expansion essel.
4. Remo e the head on the inlet control set by unscrewing, and clean the mesh filter within.
5. The benchmark ser ice record supplied within this manual should be updated at each ser ice.
YOUR GUARANTEE MAY BE VOID WIT OUT PROOF OF ANNUAL SERVICING. T E COMMISSIONING CERTIFICATE
SUPPLIED AT T E REAR OF T IS MANUAL S OULD ALSO BE COMPLETED BY T E INSTALLER.

GUARANTEE
The iSteel stainless steel essel carries a 25 year guarantee against faulty materials or manufacture pro ided that:
•It has been correctly installed as per this document and all the rele ant standards, regulations and codes of practice
in force at the time.
•It has not been modified in any way, other than by ATAG Heating Technology UK Ltd.
•It has not been misused, tampered with or subjected to neglect.
•It has only been used for the storage of potable water.
•It has not been subjected to frost damage.
•The unit has been ser iced annually.
•The benchmark ser ice record has been filled in after each annual ser ice.
•The guarantee period starts from the date of purchase and no registration is required.
•The extended guarantee is not transferable, and rests with the original householder.
•The system is fed from a public mains water supply.
•Store temperatures do not exceed 65°C.
•Installations are made only in the UK & Republic of Ireland.
•The water supply does not ha e a Chloride content greater than 250ppm.
•Units are not installed with uncontrollable heat sources (E.g. Wood Burning Sto es).
•For commercial / hea y duty installations where constant usage / reheat is required Titanium immersion heaters
must be fitted in order to comply with the warranty.
Please note that in oices for ser icing may be requested to pro e that the unit has been ser iced annually. All the
components fitted to / or supplied with the iSteel carry a 2 year guarantee. The guarantee starts when the cylinder is first
filled.
EXCLUSIONS – T INGS T E GUARANTEE DOES NOT COVER
The effects of scale build up. Any labour charges associated with replacing the unit or its parts. Any consequential losses
caused by the failure or malfunction of the unit.
GUIDANCE IN T E EVENT OF A PROBLEM
If you ha e a problem in the first year contact the plumber who fitted the unit. Thereafter contact the plumber who
carries out the annual ser icing for you. If your iSteel de elops a leak we will supply you with a new one. We ask for an
up-front payment to pre ent fraud.
We will require the original unit to be returned to us for inspection along with a copy of your ser ice record and
commissioning check sheet. If it is confirmed that it has failed within the terms of the warranty your upfront payment
will be refunded. If a component part fails within the two year guarantee period we will send you a new one again with
an upfront charge. Credit card details may be taken to pre ent fraud. We ask you to post the faulty part back to us within
one month by recorded deli ery. Once the part has been tested and pro en faulty a refund will be issued.
USER INSTRUCTIONS
Your stainless system is automatic in normal use and requires only annual ser icing. You should employ a competent
installer to perform the annual ser icing. Normally this is timed to coincide with the annual boiler ser ice.
IF WATER IS FLOWING FROM T E SAFETY VALVES T ROUG T E TUNDIS T IS INDICATES A
FAULT CONDITION AND ACTION IS NEEDED.
If this water is hot turn the boiler and / or the immersion heater off. Do not turn off the water until the discharge runs
cool. The discharge may also stop.
CALL A COMPETENT PLUMBER OUT TO SERVICE T E UNIT.
Tell them you ha e a fault on an un ented cylinder. We stock all the spare parts they may need.
PLEASE NOTE
Before making any claim/return on a iSteel Cylinder or Component, please make sure you ha e run through the following
fault finding options and check the offending item is less than one year old or the unit has been ser iced e ery 12 months
in line with the Benchmark Scheme.
Proof of this will be required when returning any part, also note all components are date stamped. Failure to do this will
result in any credit/claim being rejected.

FAULT FINDING INFORMATION
UNVENTED CYLINDER
Symptoms
Possible causes
Follow up action
Cylinder appears to leak
from within the case. Loose cylinder Connection.
Check all connection points including
immersion heaters to ensure integrity
of joint and remake any suspect joints.
Expansion valve operates
and water is visible at the
Tundish.
P
ossible fault at Pressure Reducing
al e.
Follow fault finding information for
Inlet Control Group.
Back pressure from the system.
Check all mixer type outlets are ser ed
by a balanced cold ser ice. Where not
re-pipe or install bespoke pressure
reducing al e to offending outlet.
Expansion valve operates
when cylinder is heated. Possible fault at Expansion Vessel.
Follow fault finding information for
Expansion Vessel.
Noise when operating tap
outlet. Insecure pipework. Increase the number of pipe clips.
Reduced Water flow.
External work to public mains.
Wait for works to be completed.
Debris from water mains.
Strip & Clean or replace Inlet Control
Group.
Pressure reducing al e sticking.
Strip & Clean or replace Inlet Control
Group.
No hot water available.
Immersion heater failure.
Follow fault finding information for
immersion heater.
Boiler failure.
Check operation of the boiler and its
controls.
EXPANSION VESSEL
Symptoms
Possible causes
Follow up action
Discharge of water from the
relief valve.
Expansion Vessel is too small.
Vessel needs resizing and installation by
appropriately qualified engineers.
Pre-charge set incorrectly on essel
installation.
Pre
-
charge requires setting while
system is de-pressurised according to
cylinder manufacturer’s
recommendations.
Membrane is ruptured and may require
replacement.
Replace membrane or entire essel.
Inspect Shrader al e for leaks or
damage.
Membrane may be partially
de-pressurised due to natural losses
and require re-pressurisation.
Re
-
pre
ssurise or consider replacement
depending on ae of essel and amount
of pressure lost. Inspect Shrader al e
for leaks or damage.
Leak from flange or water
connection.
Failure of Flange Plate.
Replace Flange Plate or entire essel.
Loss of torque in Fla
nge retaining bolts.
Re
-
tighten bolts as needed.
Ruptured membrane has caused
corrosion of essel body resulting in
pinhole leak.
Entire essel must be replaced. Inspect
Shrader al e for leaks or damage.
Vessel appears to be full of
liquid when system is cold. Membrane is de-pressurised.
Replace membrane or entire essel.
Inspect Shrader al e for leaks or
damage.
Water is discharged from
vessel when Shrader pin is
de-pressed for inspection of
air pressure.
Membrane is ruptured. Membrane or essel requires
replacement.