OSO HOTWATER Slimline RI 150 l. Instruction Manual

11001837-142037-06 - 09-2022
Slimline - RI
150 l.
EN
SAFETY INFORMATION
O&M INFORMATION
INSTALLATION MANUAL
TDS - TECHNICAL DATA SHEET

2
CONTENTS
1. General information
1.1 Product identification..........................................4
1.2 UKCA Marking. .....................................................4
1.3 Erp Data.....................................................................4
1.4 General information ...........................................4
1.5 Handling. ..................................................................5
1.6 Clearances. ...............................................................5
2. lnstallation.
2.1 Health and safety regulations ........................ 6
2.2 Siting the Slimline................................................ 6
2.3 Component check Iist........................................ 6
2.4 Supply requirements .........................................6
2.5 Expansion vessels. .............................................. 6
2.6 Preliminary wiring................................................ 6
2.7 Pipework...................................................................6
2.8 Piping diagrams .................................................. 9
3. Commissioning and installation
3.1 Filling up ................................................................. 10
3.2 Draining .................................................................. 10
3.3 System flushing ................................................. 10
4 Electrical installation
4.1 Thermostat connection ....................................11
4.2 Immersion heaters ............................................11
4.3 Motorized valve ..................................................11
Symbols used in this manual:
!
WARNING Could cause serious injury or death
!
CAUTION Could cause minor or moderate injury or damage to property
DO NOT
!
DO
!
This document must be kept in a suitable place where it is accessible for future reference.
4.4 Electrical spare parts ........................................11
4.5 S plan wiring layout ......................................... 12
4.6 Y plan wiring layout ......................................... 13
5. Maintenance, safety and servicing
5.1 Draining/flushing................................................ 14
5.2 Recommissioning ............................................. 14
5.3 Safety and maintenance ............................... 14
5.4 Corrosion resistance ........................................ 14
5.5 Fault finding flow charts ................................ 15
6. Alternative discharge & secondary return
6.1 Alternative discharge ....................................... 18
6.2 Secondary return ............................................. 18
7. Technical specification
Commisioning and service logbook .............. 19
Service interval record.............................................23
8. Warranty conditions
Warranty.........................................................................22
8.1 Customer service ................................................22
9. Removing the product
9.1 Removal...................................................................22
9.2 Returns scheme ..................................................22

3
Safety instructions
• Read the following safety instructions
carefully before installing, maintaining or
adjusting the water heater.
• Personal injury or material damage may
result if the product is not installed or
used in the intended manner.
• Keep this manual and other relevant doc-
Safety instructions for installers
!
WARNING
The overflow from the safety valve must NOT be sealed or plugged.
!
Discharge must comply with current building regulations.
!
Fixed electric fittings shall be used for installation in new homes or when changing an
existing electrical setup in accordance with local regulations.
!
The mains cable shall withstand 90°C. A strain reliever must be fitted.
!
The product shall be filled with water before the power is switched on.
!
The relevant regulations and standards, and this installation manual, must be followed.
Safety instructions for users
!
WARNING
The overflow from the safety valve must NOT be sealed or plugged.
The product must NOT be modified or changed from its original state.
Children must NOT play with the product or go near it without supervision.
!
The product shall be filled with water before the power is switched on.
!
Maintenance/settings shall only be carried out by persons over 18 years of age, with suf-
ficient understanding
!
CAUTION
The product must not be exposed to frost, over-pressure, over-voltage or chlorine treat-
ment. See warranty provisions.
Maintenance/settings shall not be carried out by persons of diminished physical or men-
tal capacity, unless they have been instructed in the correct use by someone responsible
for their safety.
!
CAUTION
!
The cylinder must be installed complying with current building regulations. Liability for
consequential damage will only apply if this is followed.
!
The product shall be properly aligned vertically and horizontally, on a floor or wall suit-
able for the total weight of the product when in operation. See type plate.
!
The product must have a clearance for servicing of 40 cm. in front of the electric junction
box covers / 40 mm. above the highest point.
uments where they are accessible for fu-
ture reference.
• The manufacturer assumes compliance
(by the end-user) with the safety, oper-
ating and maintenance instructions sup-
plied and (by the installer) with the fitting
manual and relevant standards and regu-
lations in effect at the date of installation.
This OSO product is approved to building and water regulations by KIWA Watertec Ltd.
Tel: [phone] • Email: [email protected]

4
1. GENERAL INFORMATION
1.1 Product Identification
Identification of your product can be found on the
label attached to the product. The label contains
information about the product according to EN
12897: 2016 and EN 60335-2-21, in addition to
other useful data. See Declaration of Conformity
at www.osohotwater.com for more information
OSO products are designed and manufactured
according to:
• Tank standard EN 12897:2016
• Safety standard EN 60335-2-21
• Welding standard ISO 3834-2
OSO Hotwater AS is certified according to
• Quality ISO 9001
• Environment ISO 14001
• Working Environment ISO 45001
1.2 UKCA marking
The UKCA mark shows that the product complies
with the relevant Directives. See Declaration of
Conformity at www.osohotwater.com for more
information.
The product complies with Directives for:
• Low voltage LVD 2014/35/EU
• Electromagnetic compatibility EMC 2014/30/EU
• Pressurised equipment PED 2014/68/EU
1.4 General information
Thank-you for purchasing the OSO Slimline RI /
RD indirect / direct hot water cylinder.
This manual gives detailed advice for installation
and shall be read carefully prior to fitting any un-
vented unit. OSO Slimline cylinders are not suit-
able for gravity fed primary systems. In known
hard water regions, precautions must be taken
to prevent limescale formation in hot water
cylinders, in accordance with Building Regulation
Part L, Domestic Heating Compliance Guide.
This OSO cylinder must be installed by
a competent person and be installed in
compliance with the OSO Installation and
Maintenance Instructions, all current legislation,
codes of practice and regulations governing the
installation of unvented hot water cylinders in
force at the date of installation.
1.3 ErP data - Technical Data Sheet
Trade mark M T.
item no. Model/identifier ErP Rating
Heat
loss W
Storage
volume L
OSO Hotwater AS 1326200 RI 150 - 3 kW / 1x240V C 76 141
Directive: 2017/1369/EU Regulation: EU 812/2013 Directive: 2009/125/EC Regulation: EU 814/2013
Standing heat loss according to standard: EN 12897: 2016
TDS - Technical Data Sheet - Direct electric water heater - ErP data
!
CAUTION
The indirect hot water storage tank (Slimline RI) is intended to be connected to a high efficiency external energy
source. The immersion heaters are intended for backup and supplementary use only. Immersion heaters as sole
heat source should be avoided and would lead to higher energy consumption and higher operating cost.

5
1.5 Handling, location and positioning
The product shall be transported carefully as
shown, with packaging. Use the handles in the
box.
1.6 Clearances
!
CAUTION
!
The cylinder must be installed complying with current building regulations.
!
The product shall be placed in a dry and permanently frost-free position.
!
The product shall be placed on a floor or wall suitable for the total weight of the product
when in operation.
!
The product must have a clearance for servicing of 40 cm. in front of the electric junction
box covers / 40 mm. above the highest point.
!
The product shall be easily accessible in the home for servicing and maintenance.
!
CAUTION
Tappings, valves etc. shall not be used to lift
the product as this could cause malfunction.
Min.
400 mm
Min. 150 mm
Min. 400 mm

6
2. INSTALLATION
2.1 Health and safety regulations
Handling Operations Regulations 1992 defines
manual handling as: “any transporting or support-
ing of a load (including the lifting, putting down,
pushing, pulling, carrying or moving thereof by
hand or bodily force”. The Regulations set no spe-
cific requirements such as weight limits. However
common sense still has to be used based on an
ergonomic approach for each individual.
The Slimline should be transported and stored in a
vertical position.
2.2 Siting the Slimline
There are few restrictions on the siting of the OSO
Slimline, however it should not be sited anywhere
open to frost attack.
The unit should be placed on a stable flat surface
capable of withstanding the weight of the cylinder
when full and access must be allowed for mainte-
nance purposes. Provision should also be allowed
for the routing of the discharge pipe away from the
cylinder to an outside point according to building
regulation G3.
2.3 Component check list
Components supplied with the unit in a separate
accessory kit for site fitting:
• Expansion vessel with wall bracket
• Pressure reducing valve multibloc 3 bar with
expansion relief valve 6 bar
• Motorized valve
• Tundish (incl. screws)
• Plastic cable clamp
• Drain cock
Components factory fitted:
• P&T valve
• Immersion heater - 3 kW
• Thermostat(s) / thermal cut-out
Documentation supplied:
• Installation manual & service logbook
2.4 Supply requirements
An uninterrupted 22 mm cold water mains supply
is recommended, however if only a 15 mm supply is
available, this may be used provided there is suffi-
cient flow rate available. A minimum standing pres-
sure of 2.5 bar and a flow rate of 20 litres per minute
with a 1 bar dynamic pressure is recommended. The
cylinder will operate at lower pressures and flow
rates however the performance will be compro-
mised. The OSO unvented unit is designed for use
with supply pressure up to 12 bar. For pressures
over 12 bar an additional pressure reducing valve
must be fitted in the supply pipe to the unit.
2.5 Expansion vessel
An expansion vessel with wall bracket is supplied
with unit. The vessel accommodate expanded wa-
ter when the cylinder is heated and prevents the
cylinder reaching its maximum working pressure.
2.6 Preliminary wiring
Before final installation and pipe fitting it is rec-
ommended to feed the electrical wires to the
electrical box. The OSO Slimline is supplied with
all internal wiring factory fitted.
For more information about electrical installations
see chapter 4. ELECTRICAL INSTALLATION.
2.7 Pipework
Cold water supply:
1. To obtain the best performance from your
OSO unvented system it is advisable to feed
the unit with an uninterrupted supply.
2. Before connecting to the multibloc, flush the
cold supply pipework of all flux and debris.
3. Locate the water heater in a suitable position
to facilitate the installation of the cold water
supply, discharge fittings and pipework. Also
take into account access to the immersion
heater.
4. Fit a 3/4” - 22 mm elbow (not supplied) to
cold supply point so that the compression
fitting is vertical.
5. Fit a drain valve at the lowest point of the
cold water supply pipe (not supplied).
6. Fit a length of copper tube 22 mm to the
cold feed elbow to include a Tee piece if a
secondary return is required
7. Fit the Pressure Reducing Valve to the top of
the copper tube.
8. Connect 15 mm copper tube from the expan-
sion relief valve (4) and also from the T & P
valve (5) and join together in a Tee as shown
in illustration.
9. Fit the tundish (6) to the bottom connection
of this tee.

7
No. Description Part No.
1 Return Boiler - 3/4” BSP
2 Flow Boiler - 3/4” BSP
3
Pressure Reducing Valve Multibloc (3 bar)
includes Item 4 & 6 92043
4 Expansion relief valve (6 bar)
5 Temperature and Pressure Relief Valve 92055
6 Tundish
7 Immersion heater (3 kW) 71214
9 Immersion heater thermostat 80020
10 Thermostat boiler 80030
11 Cold Feed Tube (not supplied)
12 Hot water outlet - 3/4” BSP
13 CW inlet 3/4” BSP
14 Cable entry
15 Electrical box
16 Discharge pipe (not supplied)
17 Motorized valve (Not factory fitted) 92000
18 Expansion vessel AX 12
21 Drain cock 1/4” 156305
10. If a balanced mains pressure cold water
supply is required to a shower or bidet (over
rim type only), remove the blanking cap from
the pressure reducing valve (3) and connect
to the shower or bidet cold supply. Do not
use this balanced cold outlet to feed all cold
outlets.
11. Connect the cold supply to the PRV (3).
12. Fit the expansion vessel to the wall close to
the water heater using the enclosed mount-
ing bracket. Connect the expansion vessel to
the PRV.
Hot water supply
13. Connect the hot water supply pipe to the
outlet (12). Ensure connection is water tight.
Discharge pipe
14. Connect the discharge pipe (16) from the
tundish (6). This must have a continuous fall
and be fitted in accordance with The Build-
ing Regulations (see page 18.). The tundish
should be installed away from electrical
devices.
Boiler primaries - Primary flow & return and
motorized valve
15. The boiler primary flow and return connec-
tions should be made connections 1 & 2. The
motorized valve can be connected to either

8
the primary flow or return pipe. The primary
flow and return fittings are 3/4’’ BSP female.
The valve has 22 mm x copper connections.
The direction of primary flow in the coil is
bottom to top. The maximum operating
temperature of the primary flow would typi-
cally be 82°C.
16. For electrical connection of the motorised
valve and immersion heater, please read
Electrical Installation Instructions..
Tundish
17. Install the Tundish (6) in a vertical position
within a maximum of 600 mm from the
temperature and Pressure Relief Valve drain
connection (5). Ensure the expansion relief
pipework discharges through the tundish.
Tundish pipework (16) must be 22 mm with
a minimum vertical length of 300 mm below
tundish. Maximum permitted length of 22
mm pipework is 9 m. Each bend or elbow is
equivalent to 0.8 m of pipework. All pipework
must have continuous fall and discharge in
a safe, visible position. If any doubt, refer to
Building Regulation G3.
Drain cock
18. Fit the drain cock (supplied) to the 1/4” drain
connection (21), see illustration. It is also
recommended to add a drain cock (25) (not
supplied) on lowest point of cold water inlet
supply (13), see illustration.
16
5
6
13
25
21

9
2.8 Piping diagrams
Pump
flow
2-port valve
(supplied)
Zone valve
(not supplied)
Automatic
bypass
Radiators/
UFH
Boiler
Pump
flow
2-port valve
(supplied)
Mid pos. valve
(not supplied)
Radiators/
UFH
Boiler
Automatic
bypass
S-plan piping diagram
Y-plan piping diagram

10
3. COMMISSIONING & INSTALLATION
3.1 Filling up
1. Open a hot tap.
2. Open the cold water supply valve
3. When water flows from hot tap, close the tap
4. Allow the system to stabilize for 5 minutes
5. Open each hot water tap in turn to expel air
from the system pipe work.
6. Check for leaks.
7. Manually operate Temperature and Pressure
Relief Valve (5) to ensure free water flow
through discharge pipe. (Turn knob left.)
3.2 Draining
Switch off the electrical power (important to avoid
damage to element (8)). Turn off the cold water
supply valve. Open hot water tap. Drain cylinder
by opening optional drain cock (not supplied) on
cold supply pipework (25). If bottom immersion (8)
is to be replaced then additionally open drain cock
at base of cylinder (21). The unit will drain. Drain-
ing process may be speeded up by opening the
temperature and pressure relief valve. A hose can
be applied to bottom drain cock to lead the water
to a gully, sink or similar.
3.3 System flushing
System flushing will not be necessary under nor-
mal circumstances as the line strainer will prevent
ingress of foreign materials, however if flushing is
required, run at least 50 litres of water from the
cylinder at the highest possible flowrate. Close the
taps and follow draining procedure above.
A temperature sensor bracket (22) is factory fitted
in the upper electrical box, see pt. 4.2.1.
Data tables
Note: Temperature rise is from 15 to 60°C. Coil
heating performance based on a primary flow rate
of 15 l/min. at 80°C. Test results are in accordance
with BS EN 12897:2016.
Product
ref.
Max. design
pressure
Operating pressure
CW feed & coil
Pressure drop
primary heater coil
Temp./pressure
relief valve
Safety valve
Pressure/conn.
Exp. vessel
capacity
RI 150 6 bar Cw in 3 bar, coil 2.5 bar 0.04 bar 90-95°C / 10 bar 6 bar / 15 mm - 1/2” 12 l.
Product
ref.
Weight
empty
Weight
full
Heat-up (mins)
coil/element
Rating (kW)
coil/element
Heat loss
kWh/24h
Recovery
rate 70%
Primary
flow rate
Volume mixed
to 40°C
RI 150 43 184 24.3 16.5 / 3 1.8 17 15 l/min. - 80°C 221 ltrs.
13
25
24
21
22
23
5
6
16
8

11
4. ELECTRICAL INSTALLATION
4.1 Thermostat connection
The power supply cable to the upper electrical
box (23) is fed through the cable fastener fitted
to the box cover. The power cable to the lower
electrical box (24) is fed up from the bottom of
the product, see illustration on previous page.
Use supplied cable fastener. All wiring must be
fitted by authorized electrician, who must ensure
suitable cable quality is used.
When connecting cables to thermostats, use
spade connectors as shown in diagram. Ensure
that connector is less than 10 mm in outer di-
mension and fits inside the shoulders of the ther-
mostat and is not tightened onto the top of the
shoulders.
4.2 Immersion heaters
All units are fitted with an immersion heater
which is located behind the bottom electrical
box cover. Wiring instructions for the immersion
heater is located on the reverse side of the elec-
trical box lid.
Follow the wiring instructions connecting the
live, neutral and earth as indicated. A dedicated
permanent supply complying with current IEE
regulations should be used, and each circuit
must be protected by a suitable MCB and double
pole isolating switch with a contact separation of
at least 3 mm in both poles. All cables should
comply with BS6141 table 8 HOFR 85c.
All internal wiring is factory mounted. The im-
mersion heater has a working thermostat adjust-
able between 40°C - 70°C. A safety cut-out is also
incorporated within the thermostat and will op-
erate at 85°C ± 3°C. Should this happen, press
the reset button.
Important: Before resetting the safety cut-out or
altering the thermostat setting, isolate electrical
supply to the unit prior to removal of the lid. En-
sure the lid to the electrical box is replaced cor-
rectly and the retaining screw is fitted.
4.2.1 Temperature sensor installation
A temperature sensor bracket (22) is factory fit-
ted to the upper electrical box, see illustration
on previous page. Ensure the sensor has proper
contact with the inner vessel when fitting.
4.3 Motorized valve
To comply with regulations governing the in-
stallation of indirect unvented cylinders, a mo-
torised valve must be fitted in the primary flow
or return. Your OSO unit has been supplied with
a two port motorised valve, which will act as a
positive energy cut-out should the safety cut-out
operate. The motorised valve will also control the
temperature of the domestic stored water via the
cylinder thermostat, which is located in the elec-
trical box. The unit should be installed on an “S”
or “Y” plan system.
Please follow the instructions carefully. All elec-
trical connections must conform to current IEE
wiring regulations. The working thermostat is
adjustable between 40°C - 70°C. A safety cut-out
is also incorporated within the thermostat and
will operate at 85°C ± 3°C. Should the safety cut-
out be brought into operation, the motorised
valve will operate and close down the primary
flow to the cylinder. To reset the safety cut-out
and the motorised valve the reset button must
be pressed in (see fig.2 above).
OSO Hotwater (UK) Limited can not be responsi-
ble if alternative wiring plans are used.
Important: Before resetting the safety cut-out or
altering the thermostat setting isolate electrical
supply to the unit before removal of the lid.
4.4 Electrical spare parts
Part for Description Part No.
Indirect Immersion heater 71214
Indirect Upper thermostat 80030
Indirect Lower thermostat 80020
MAX
10 mm
Element
Reset button
Safety
cut-out
Working
thermostat
Temperature
adjustment
screw
R
E
S
E
T
R
E
S
E
T
M2
1
2
3
4
THERM-O-DISC
40°C70°C
60°C 50°C
1
2
Power
supply

12
4.5 S-plan wiring layout
OSO Slimline cylinders can be fitted with all types
of boilers. Standard boilers operate using room
and cylinder thermostats. Please follow upper
diagram: ‘Wiring for Standard Boiler’.
1 2
E
231
T6360B
B1BrG O
G/Y
3 5 7
34NL ENL ENL
ST6400 Boiler Pump
321 32 32
2 2 31
V4043H
Zone Valve (DHW)
(supplied)
Thermal Cut Out/Thermostat
(supplied)
Isolated Mains
Supply From
Fused Spur
L N E
Zone Valve (Htg)
(not supplied)
Room
thermostat
6 9
B1BrG O
G/Y
2 31
V4043H
4 8 10
R
E
S
E
T
R
E
S
E
T
M2
1
2
3
4
R
E
S
E
T
R
E
S
E
T
M2
1
2
3
4
1 2
E
231
T6360B
B1BrG O
G/Y
3 5 7
34NL ENL ENL
ST6400 Boiler Pump
321 32 32
2 2 31
V4043H
Room
thermostat
Zone Valve (DHW)
(supplied)
Thermal Cut Out/Thermostat
(supplied)
Isolated Mains
Supply From
Fused Spur
L N E
Zone Valve (Htg)
(not supplied)
6 9
B1BrG O
G/Y
2 31
V4043H
4 8 10
Both wiring plans shown is based on the use
of a 10-way Junction Box (Honey-well Part no.
42002116-001). Junction Box terminal 8 is switched
live and, if needed, terminal 10 is pump live.
Wiring for standard boiler
Wiring for thermistor controlled boiler
Spare parts, see pt. 4.4
Piping diagram, see pt. 2.8
Spare parts, see pt. 4.4
Piping diagram, see pt. 2.8

13
4.6 Y-plan wiring layout
OSO Slimline cylinders can be fitted with all types
of boilers. Standard boilers operate using room
and cylinder thermostats. Please follow upper
diagram: ‘Wiring for Standard Boiler’.
Y-plan systems with unvent-ed cylinders require
use of both a mid-position valve and the supplied
R
E
S
E
T
R
E
S
E
T
M2
1
2
3
4
1 2
E
231
T6360B
B1OG Br
G/Y
3
3 14NL ENL ENL
ST6400 Boiler Pump
321 32 32
2 2 31
V4043H
Room
thermostat
Zone Valve (DHW)
(supplied)
Thermal Cut Out/Thermostat
(supplied)
Isolated Mains
Supply From
Fused Spur
L N E
Mid Position Valve
(not supplied)
6
WB1 G/Y Gr O
23
V4073A1039
104 5 987
R
E
S
E
T
R
E
S
E
T
M2
1
2
3
4
1 2
E
231
T6360B
B1OG Br
G/Y
3
3 14NL ENL ENL
ST6400 Boiler Pump
321 32 32
2 2 31
V4043H
Room
thermostat
Zone Valve (DHW)
(supplied)
Thermal Cut Out/Thermostat
(supplied)
Isolated Mains
Supply From
Fused Spur
L N E
Mid Position Valve
(not supplied)
6
WB1 G/Y Gr O
23
V4073A1039
104 5 987
zone valve. Failure to use the zone valve contra-
venes regulations.
Both wiring plans shown is based on the use
of a 10-way Junction Box (Honey-well Part no.
42002116-001). Junction Box terminal 8 is switched
live and, if needed, terminal 10 is pump live.
Wiring for standard boiler
Wiring for thermistor controlled boiler
Spare parts, see pt. 4.4
Piping diagram, see pt. 2.8
Spare parts, see pt. 4.4
Piping diagram, see pt. 2.8

14
5. MAINTENANCE, SAFETY AND SERVICING
Maintenance must be carried out by a compe-
tent person.
5.1 Draining/flushing
1. Turn off mains supply.
2. Connect hose pipe to drain cock on cold wa-
ter supply pipework. If bottom immersion is
to be replaced then additionally open drain
cock at base of cylinder (21).
3. Open hot tap. Open temperature & pressure
relief valve.
4. Allow vessel to drain. Follow commissioning
instructions (above) to refill.
5.2 Recommissioning
Cold or tepid water discharge from tundish
The tundish should be installed away from electri-
cal devices.
1. Close cold water supply valve
2. Open a hot tap.
3. Repressurize the expansion vessel air charge
to its set level.
4. Close hot tap
5. Open the cold water supply valve
Hot water discharge from tundish: This indicates a
malfunction of a thermal cut-out, operating ther-
mostat or the combined temperature and pressure
relief valve. Turn off the electrical supply to the
immersion heater and also isolate an indirect unit
from the boiler.
Contact the installer or competent engineer.
5.3 Safety and maintenance
Safety cut-out
1. The safety cut-out operates if:
a). Wiring is incorrect.
b). The immersion heater thermostat or
cylinder thermostat fails.
c). Thermostat is set too high.
2. Remember before resetting the safety cut-
out or altering the thermostat setting, isolate
electrical supply to the unit prior to removal
of the electrical box lid.
3. Reduce thermostat setting and press the re-
set button. After adjustments are completed,
ensure the lid to the electrical box is replaced
correctly and the retaining screw is fitted.
4. If still out of operation, contact installer.
Pressure reducing valve
1. Isolate the cold water supply and open a
ground floor cold tap.
21
Reset button
Safety
cut-out
Working
thermostat
Temperature
adjustment
screw
R
E
S
E
T
R
E
S
E
T
M2
1
2
3
4
THERM-O-DISC
40°C70°C
60°C 50°C
1
2
Power
supply

15
2. Unscrew the pressure reducing cartridge
3. Clean the filter mesh and the cartridge under
running water.
4. Replace cartridge ensuring that strainer is
correctly located and reassemble the unit.
Pressure Reducing Valve cartridge and
strainer Part No. REDC355030 - 3 Bar.
Expansion relief cartridge
1. Isolate the cold water supply and open a
ground floor cold tap.
2. Unscrew blue expansion relief headwork
from valve body.
3. Clean valve seat face and seating - do not
scratch or damage either seat face or seating.
4. Refit in reverse order. Do not overtighten
Expansion valve cartridge and seat Part No.
RELC 214005 6.0 Bar.
Complete Expansion Valve Part No. PREL
355030.
Expansion vessel
Repressurizing vessel:
1. Close cold water supply valve
2. Remove cap covering air valve
3. Adjust the vessel air pressure in relation to
the set incoming water pressure using an air
compressor or hand pump.
4. Replace the air valve cap.
Note: If water emits from the air valve the vessel is
punctured and must be replaced.
It is a condition of the warranty that annually a
competent person:
1. Inspects and cleans the line strainer.
2. Checks the operation of the expansion relief
valve and temperature & pressure relief valve.
3. Recommissions the cylinder in accordance
with the instructions above.
4. Checks the thermostat and visually inspect
the immersion heater.
5.4 Corrosion resistance
Stainless steel is naturally corrosion resist-
ant to mains water supply. No specific main-
tenance is required to maintain this resistance.
Please see warranty terms for permissable wa-
ter content. Please note: OSO cylinders are not
warranted for use with a private water supply.
The immersion heater can be removed to provide
visual inspection access to the cylinder.
For further information contact your Building
Control Office.

16
Reduced expan-
sion volume
Repressurize
expansion vessel,
see pt. 5.3
Mains supply off
Open supply
valve
Line strainer
blocked
Clear line
strainer
Thermal control
failure
Switch off power to
immersion heaters
and boiler supply to
the unit. When dis-
charge has stopped
check thermal con-
trols and replace as
necessary
Cold water PRV
incorrectly fitted
Check and refit
as required
Intermittent water discharge
If problem stil persists contact a competent
engineer/plumber
No water flow from hot taps
If problem stil persists contact a competent
engineer
5.5 Fault finding flow charts
YES
YES YES
YES
YES
NO NO
!
If in doubt at any stage consult a qualied installer / electrician

17
NO
Is the programm-
er set to central
heating or not
switched on?
Check and
set to hot
water pro-
gramme
Is the mo-
trized valve
operating
correctly?
Check wiring
or plumbing
connections
Has cylinder
thermal
cut-out
operated?
Check and
press reset
button
Is the boiler
working?
Is thermostat wired
as per layouts for ‘S’
or ‘Y’ plan
installation?
Connect wiring as
per instructions
Check cylinder ther-
mostat is switch-
ing on & off with
programmer & hot
water on
Is 2-port moto-
rized valve closing
when cylinder
reaches tempera-
ture?
Check wiring on
cylinder thermostat
Wiring fault
Seek advice
from electrician
Thermostat/solar
controller set too
high
Reduce tempera-
ture setting
Faulty thermostat
Replace
Hot water from taps is cold
If problem stil persists contact a competent
engineer/plumber
Excessive hot water from taps
YES
YES YES
YES
NO
NO
NO
NO
NO
NO
YES
YES
YES
YES
YES
!
If in doubt at any stage consult a qualied installer / electrician

18
6. ALTERNATIVE DISCHARGE AND SECONDARY RETURN
6.1 Alternative discharge
Downward discharges at low level, i.e. up to 100
mm above external surfaces such as car parks,
hard standings, grassed areas etc, are accept-
able providing that where children may play or
otherwise come into contact with discharges,
a wire cage or similar guard is positioned to
prevent contact, whilst maintaining visibility.
Discharge at high level, i.e. into a metal hop-
per and metal down pipe with the end of the
discharge pipe clearly visible (tundish visible or
not) or onto a roof capable of withstanding high
temperature discharges of water and 3 m from
any plastics guttering system that would collect
such discharges (tundish visible). Where a single
common discharge pipe serves more than one
system, it should be at least one pipe size larger
than the largest individual discharge pipe (D2)
to be connected. For further information contact
your Building Control Office or The British Board
of Agrément.
6.2 Secondary return
1. Secondary return fitting
2. Non return valve
3. Circulation pump
4. Secondary return line
5. Hot water draw-off to outlets
!
WARNING
The tundish shall be installed away from any
electrical devices.

19
The code of practice for the installation,
commissioning & servicing of mains pressure hot water storage
Installation,CommissioningInstallation,Commissioning
and Service Record Log Bookand Service Record Log Book
CUSTOMER DETAILS
NAME
ADDRESS
TEL No.
IMPORTANT
1. Please, keep the Log Book in a safe place for future reference.
2. This Log Book is to be completed in full by the competent person(s) who
commissioned the equipment and then handed to the customer. When this is done,
the Log Book is a commissioning certicate that can be accepted as evidence of
compliance with the appropriate Building Regulations.
3. Failure to install and commission this appliance to the manufacturer’s
instructions may invalidate the warranty.
The above does not a󰀨ect your statutory rights.
For full details on the HWA charter please visit http://www.hotwater.org.uk/
© HEATING AND HOTWATER INFORMATION COUNCIL
IT IS THE RESPONSIBILITY OF THE INSTALLER TO COMPLETE THIS
LOG BOOK AND PASS IT ON TO THE CUSTOMER. FAILURE TO DO
SO MAY INVALIDATE THE CYLINDER WARRANTY
HWA charter members agree to:
• To supply t for purpose products clearly and honestly described
• To supply products that meet, or exceed appropriate standards and building and water regulations
• To provide pre and post sales technical support
• To provide clear and concise warranty details to customers

20
INSTALLER & COMMISSIONING ENGINEER DETAILS
INSTALLER DETAILS
COMPANY NAME DATE
ADDRESS
INSTALLER NAME TEL No.
REGISTERED OPERATIVE ID CARD No.
(IF APPLICABLE)
REGISTRATION DETAILS
COMMISSIONING ENGINEER (IF DIFFERENT)
NAME DATE
ADDRESS
TEL No.
REGISTERED OPERATIVE ID CARD No.
(IF APPLICABLE)
REGISTRATION DETAILS
IT IS THE RESPONSIBILITY OF THE INSTALLER TO COMPLETE THIS LOGBOOK AND PASS IT
ON TO THE CUSTOMER. FAILURE TO DO SO MAY INVALIDATE THE CYLINDER Warranty
APPLIANCE & TIME CONTROL DETAILS
MANUFACTURER OSO HOTWATER (UK) MODEL
CAPACITY
TYPE
TIME CONTROL
UNVENTED
PROGRAMMER
litres SERIAL No.
TIME SWITCH
or