Thermaflow TH12 Operating manual

ELECTRIC COMBINATION BOILER
(Patent Pending. Design Right Protected.)
TH12/210U, TH12/250U & TH12/330U
TH9/210U, TH9/250U & TH9/330U
(INCLUDES SOLAR APPENDIX)
This product is suitable for connection to ~230-240V, 50Hz
INSTRUCTIONS FOR USE, INSTALLATION AND
SERVICING
TO BE LEFT WITH THE USER
The instructions consist of three parts; User, Installation and Servicing instructions, which include the guarantee registration
card.
The instructions are an integral part of the appliance and must, to comply with the current issue of the building, electrical
regulations and water by-laws, be handed to the user on completion of the installation.
GUARANTEE REGISTRATION
Thank you for installing a new Thermal Innovations product in your home.
Thermal innovations appliances, are manufactured to the very highest standards so we are pleased to offer our customers, a
comprehensive first year guarantee and a second year parts guarantee.
In the instruction envelope is to be found your guarantee registration card, which must be completed and returned to Thermal
Innovations (UK) Ltd or register your Thermal Innovations (UK) Ltd appliance for 1st year guarantee protection by calling the
below number.
Our guarantee gives you peace of mind valuable protection against breakdown by covering the cost of-
• All replacement parts
• All labour charges
• All call-out charges
THERMAL INNOVATIONS (UK) LTD
31-39 Napier Court, Cumbernauld, Glasgow, G68 0LG
Customer services
Tel [phone]
Fax [phone]
Web www.thermaflowheating.co.uk
Issue Number: 2.2 Issue date: April 2008
Copyright Notice
This document contains proprietary information protected by copyright, and this Manual and documentation are copyrighted. All rights are reserved. No part of this
document may be photocopied or reproduced by mechanical, electronic, or other means in any form without permission from Thermal Innovations (UK) Ltd.
©Copyright Thermal Innovations (UK) Ltd 2006 -All rights reserved.

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Contents
0.1 ..................................................................................4Instructions general
0.2 ......................................................................................5Draining & Filling
0.3 ......................................................................5Manual Handling Guidance
0.4 ....................................................................5TESTING & CERTIFICATION
0.5 ................................................................................5THE UNIT LOCATION
Part1 - INSTRUCTIONS FOR USE............................................................................7
1.1 .........................................................................................7INTRODUCTION
1.2 .............................................................7Domestic hot water temperature
1.3 .................................................................................7To turn the boiler off
1.4 ......................................................................7Maintenance and servicing
1.5 .................................................................................................7Clearances
1.6 ....................................................................................8Draining and filling
1.7 ....................................................................................8Replacement parts
1.8 ........................................................................................9GENERAL DATA
Part 2 - INSTALLATION ..........................................................................................11
2.1.1 sheet metal parts .......................................................................................11
2.1.2 Statutory requirements .............................................................................11
2.1.3 DATA 11
2.1.4 ELECTRICAL SUPPLY...............................................................................11
2.1.5 Electrical supply ........................................................................................12
2.1.6 Heating system controls ...........................................................................12
2.2.1 Boiler Position............................................................................................12
2.2.2 Boilers in a compartment..........................................................................13
2.2.3 Clearances..................................................................................................14
2.3.1 General notes .............................................................................................14
2.3.2 Safety valve ................................................................................................14
2.3.3 Pressure Gauge .........................................................................................14
2.3.4 Pump 14
2.3.5 Expansion vessel.......................................................................................14
2.3.6 By- pass ......................................................................................................14
2.3.7 Filling sealed systems...............................................................................14
2.3.8 Corrosion inhibitor ....................................................................................14
2.3.9 Draining ......................................................................................................15
2.4. Domestic hot water system.........................................................................15
2.4.1 General 15
2.4.2 Water pressure...........................................................................................15
2.4.3 HOT WATER FLOW RATE .........................................................................15
2.4.4 Hard water areas ........................................................................................15
2.5. Installation, PREPARATION [water connections] .....................................15
2.5.1 Water connections..................................................................................15
2.5.2 Safety valve discharge ...........................................................................15
2.6 Electrical Installation Requirements ...........................................................16
2.6.1 SUPPLY .................................................................................................17
2.6.2 18
2.6.3 External Controls....................................................................................19
Electrical Connections.....................................................................................20
2.6.4 Supply cable connection [24 HR Supply] ...............................................20
2.6.5 Heating system controls.........................................................................20
2.6.6 Electrical Test.........................................................................................20
2.6.7 Supply cable connection [Interrupted off peak supply]...........................21
2.6.8 Electrical Test.........................................................................................21
Electricity tariffs ...............................................................................................21

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2.7 Commissioning .............................................................................................21
2.7.1 Filling domestic water circuit...................................................................21
2.7.2 Filling the heating system.......................................................................21
2.7.3 Domestic hot water flow rate..................................................................22
2.7.4 Temperature settings..............................................................................22
2.7.5 Heating system commissioning..............................................................22
2.7.6 Completion .............................................................................................23
Instruct the user...............................................................................................23
Part 3 - SERVICING .................................................................................................24
3.1. Fault Finding ................................................................................................24
Fault: No domestic hot water or central heating..............................................25
Fault:No central heating, but hot water at taps................................................26
Fault:CENTRAL HEATING BUT No hot water at taps ....................................27
3.2 ISOLATION ...............................................................................................28
Checking the pressure in the expansion vessel..............................................28
Checking the inline strainer.............................................................................28
Checking the hot water blending valve............................................................28
Checking the concentration of corrosion inhibitor............................................29
preventing pump seizure in summer ...............................................................29
Checking correct operation of electrical components......................................29
Low pressure switch........................................................................................29
control and high limit thermostats....................................................................29
Checking the elements....................................................................................30
Checking circuit breakers................................................................................30
Checking the contactor....................................................................................30
Check the operation of the AQUA STAT.........................................................30
Appendix I – Solar Connection..............................................................................31
A1.1 Solar Pipework Schematic......................................................................31
A1.2 Solar Wiring Schematic...........................................................................32
IMPORTANT PRE-INSTALLATION NOTES
• Power supply and wiring
The power supply to the premises must meet the minimum requirements of the unit being installed, with special
attention given to the supply current, cable size and MCB recommendation. The supply voltage to the appliance
must never drop below 207 Volts.
Important
The electrical supply requirements:-
The 9 KW and 12 KW boilers meet the requirements of EN 610000-3.3
The 9 KW and 12 KW boilers must be installed in premises having a service supply of ≥100A
per phase.
The 12 KW boiler must be installed in premises having a system impedance of not more than 0.1939 + J 0.1939Ω

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0.1 Instructions general
A pressure reducing valve must be fitted to the cold water inlet if the incoming water pressure exceeds
400 KPA (4.0 Bar).
The primary operating pressure initial charge is 120 KPA (1.2Bar) this will increase to around 200 KPA
(2.0Bar) when the system has reached maximum temperature and will depend on system volume.
The primary expansion vessel pre-charge pressure is 150 KPA (1.5 Bar) and has volume of 25 and 35
litres depending on the model of boiler.
The secondary expansion vessel pre-charge pressure is 350 KPA (3.5 Bar) and has a volume of 1 or 2
litres.
The primary pressure relief valve is set to 300 KPA (3.0 Bar).
Thermaflow Model Number
TH9/21OU & TH12/210U TH9/250U & TH12/250U TH9/330U & TH12/330U
Primary storage capacity 210 litres 250 Litres 330 Litres
Weight when Empty 60KG 65KG 75KG
Weight when Full 270KG 315KG 405KG
WARNING: BEFORE OBTAINING ACCESS TO TERMINALS, ALL SUPPLY CIRCUITS MUST
BE DISCONNECTED.
The TH9/21OU, TH9/25OU and TH9/330U all have 3 heating elements fitted. Size 16” in length and are
manufactured of incaloy EN60335.2.73.
The rated power input of the appliance is ~230- 240V, 50Hz, 8,250-9,000w
The TH12/210U, TH12/250U and TH12/330U all have 4 heating elements fitted. Size 16” in length and
are manufactured of Incaloy EN60335.2.73.
The rated power input of the appliance is ~230-240V, 50Hz, 11,000-12,000w
The elements fitted to the Thermaflow should NOT be replaced with elements which have no thermal
cut outs.
It is recommended that the Thermaflow has a safety and maintenance check on an annual basis.
A pressure reducing valve must be fitted to the cold water inlet of the appliance if the incoming
pressure exceeds 400kPA (4 Bar).
The position of the Tundish (IF REQUIRED) shall be visible to the occupants and shall be
positioned away from any electrical devices.
The position of discharge pipes, (Tundish), drain valves and motorised valves etc, must be
positioned away from electrical components.
The water may drip from the discharge pipe of the pressure-relief device and must be left open
to the atmosphere.
The pressure relief device must be operated regularly to remove lime deposits and to verify that
it is not blocked.
The discharge pipe connected to the pressure-relief device must be installed in a continuously
downward direction and in a frost free environment.

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(Additional Information given in G3 of the building regulations for discharge pipes)
0.2 Draining & Filling
CAUTION: THE THERMAFLOW BOILER WORKS IN A PRESSURISED SYSTEM WHICH
MUST ONLY BE DRAINED, REFILLED AND PRESSURISED BY A COMPETENT PERSON.
There are two drain taps fitted to the Thermaflow boiler, one to drain the potable circuit within the boiler
and one to drain the primary circuit within the boiler both drain taps are located at the bottom of the
appliance. Further drain taps should be fitted into the pipe-work at the lowest point of the potable water
circuit and the heating circuit and should terminate outside the dwelling in a suitable position.
0.3 Manual Handling Guidance
During the appliance installation it will be necessary to employ caution and assistance whilst
lifting as the appliance exceeds the recommended weight for a one man lift.
DO NOT LIFT THE APPLIANCE BY ATTACHED PIPE-WORK OR COMPONENTS
In certain situations it may be required to use a mechanical handling aid.
Take care to avoid trip hazards, slippery or wet surfaces.
IMPORTANT INFORMATION
0.4 TESTING & CERTIFICATION
The boiler is tested and certified for safety and performance. It is therefore important that no alteration
is made to the boiler, without permission, in writing, from Thermal Innovations (UK) Ltd.
Any alteration not approved by Thermal Innovations (UK) Ltd, could invalidate the certification, boiler
warranty and may also infringe the current issue of the statutory requirements, see section 2.1.2
The unit should be stored in a dry environment and should be handled with care to prevent attached
components being damaged or connections becoming loose. All connections should be checked for
leaks after installation.
0.5 THE UNIT LOCATION
The unit should be preferably located in a cupboard with a minimum dimension of;
L 800 mm x B 750 mm H 2.1m for the TH9/21OU & TH12/210U.
L 800 mm x B 750 mm X H2.4M for TH9/250U & TH12/250U
L. 820 mm x B. 750 mm x H. 2.4M for the TH9/330U & TH12/330U.
The floor to which the unit is placed upon should be capable of withstanding a load of:
270KG for the TH9/21OU & TH12/210U
315KG for the TH9/250U & TH12/250U
405KG for the TH9/330U & TH12/330U.
The unit should be positioned in a manner that allows access to all components for future
maintenance. If located in a cupboard the unit should be positioned with all components facing
the entrance to allow elements to be replaced if required or any of the other components.

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There are five water connections to be made when installing the Thermaflow, they are as follows:
1) Flow and return connections to the heating system are 22mm compression.
2) Cold water inlet-22mm compression.
3) Hot water outlet -22mm compression.
4) Pressure relief valve- 15mm compression with a 15mm Tundish.
5) The pressure relief valve connection should be used for no other purpose.

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PART1 - INSTRUCTIONS FOR USE
1.1 INTRODUCTION
This appliance is not intended for use by persons (including children) with reduced physical,
sensory or mental capabilities, or lack of experience and knowledge, unless they have been
given supervision or instruction concerning use of the appliance by a person responsible for
their safety.
Children should be supervised to ensure they do not play with the appliance.
Please read these Instructions and follow them carefully for the safe and economical use of your
combination boiler.
This boiler must have been installed by a competent person in accordance with the current rules in
force in the countries of destination at the time of installation.
The boiler is automatic in operation once the external controls are set e.g. time clock or
programmable room thermostat.
IMPORTANT NOTICE
1.2 Domestic hot water temperature
Hot water is user adjustable by turning the control knob on the thermostatic mixing valve fitted on the
hot water outlet at the top left of the boiler. It has a maximum anti-scald cut off at 63oC.
The combination boiler is able to provide room heating as part of an underfloor or central heating
system and domestic hot water direct from the cold water supply, without the need for secondary
storage.
1.3 To turn the boiler off
To turn the boiler off, isolate the boiler from both the electrical supplies i.e. the 24hr supply and the
interrupted supply, both isolating switches should be positioned next to the boiler.
1.4 Maintenance and servicing
To ensure the continued efficient and safe operation of the appliance it is recommended that it is
checked and serviced as necessary at regular intervals. The frequency of servicing will depend upon
the particular installation conditions and usage, but in general once a year should be enough.
Servicing & maintenance should be carried out by a competent person in accordance with the rules in
force in the countries of destination.
To obtain service please call your installer or Thermal Innovations (UK) Ltd, using the telephone
number on the appliance or at the front of this manual.
Please be advised that the Thermal Innovations (UK) Ltd log book should be completed by the
installation engineer on completion of commission and servicing.
1.5 Clearances
The boiler requires a clearance in front and at the sides for safety, servicing and maintenance access,
see diagram 2.2.3 for the requirements.

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1.6 Draining and filling
Caution this boiler works in a pressurised system which must only be drained, refilled and pressurised
by a person competent to do so.
Note: if the pressure gauge indicates a loss of pressure that is less than 60 KPA (0.6 Bar) YOU MUST
CONTACT YOUR INSTALLER. Unless you have been instructed by your installer on how to re-pressurise
the system correctly.
1.7 Replacement parts
If replacements parts are required, contact your Installer, Service Company or Thermal Innovations
(UK) Ltd. Please quote the name and model of your appliance. (Ref. Spare Parts List - section 1.8.1).

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1.8 GENERAL DATA
Diagram 1.8.1 1 Enclosure for Low
Pressure cut-out switch
& Master non-reset-able
over-temperature
thermostat
2 Safety Relief Valve
300kPA (3bar)
3 Enclosure for Contactor
and Circuit Breakers
4 22mm Compression
bends DZR
5 Pipe work
6 Filling Loop Assembly
6a Pressure gauge
7 Circulating Pumps
Complete with Isolating
Valves.
7a – Central Heating
Pump
7b – Grundfos
circulating pump HW
circuit
8 Heating Elements
9 Aqua Thermostat
10 10-1 Enclosure for
incoming live supply,
central heating pump &
Aqua stat
10-2 Enclosure for flow
switch relay & pump for
domestic HW circuit
11 Heat Resistant Flex
12 1 or 2 Litre Potable
expansion vessel
13 Thermostatic Blending
Valve
13b HW outlet
14 Plate Heat Exchanger
15 Automatic Air Eliminator
16 Stainless Steel Primary
Store
17 17-1 Single check valve
– cold water inlet
17-2 Single check valve
– CH flow
17-3 Y-pattern strainer
(cold water inlet)
18 18-1 Drain point
(potable)
18-2 Drain point
(primary)
19 Flow switch
20 Primary Expansion
vessel – connect into
CH return at boiler
Unit Design (Protected by Design Rights)
9

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TABLE 1.8.1 [DATA]
TH9/12/210 TH9/12/250 TH9/12/330
Lift Weight 60KG 65KG 75KG
Total Weight 70KG 77KG 85KG
Weight Full 270KG 315KG 405KG
Heating Flow Return 22mm Compression
Domestic Cold Inlet 22mm Compression
Domestic Hot Outlet 22mm Compression
Safety Valve PRESET 300 KPA (3.0 Bar)
Safety Valve Discharge 15mm Compression
Water Content Primary 210 Litres 250 Litres 330 Litres
Water Content Domestic 6 Litres / 1.32 Gallons
Primary Expansion Vessel 25 Litres / 5.5 Gallons / 35Litres/7.7 Gallons
Htg Cold Fill Pressure Min/Max 90 KPA (0.9 Bar) minimum / 120 KPA (1.2 Bar) maximum
D.H.W Working Pressure 20 – 400 KPA (0.2-4.0 Bar)
Max. Htg system Content (Excluding unit volume) 110Litres 130Litres 150Litres
Electrical Mains Supply ~230-240V, 50Hz
Electrical Rating (Interrupted) & Supply Current TH9/ 8,250-9,000w- 40amp
TH12/ 11, 000-12,000w – 52 amp
MCB Rating (amp) 9Kw (40amp) 12Kw (52amp)
Electrical Rating (24Hr 190w, Fused 3amp

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PART 2 - INSTALLATION
2.1.1 Sheet metal parts
Warning: when installing or servicing this boiler care should be taken when handling the edges of
metal parts to avoid any possibility of personal injury.
2.1.2 Statutory requirements
The installation of this boiler must be carried out by a competent person in accordance with the current
rules in force in the countries of destination at the time of installation, and in accordance with the
relevant requirements of the current issue of:
The Building Regulations
The Local Water Company bye-laws
The Building Standards Regulations (Scotland)
The Health and Safety at Work Act
Manufacturers instructions, supplied
Manufacturer’s instructions must not be taken as overriding statutory requirements.
2.1.3 DATA
The data label is on the front case of the boiler.
2.1.4 ELECTRICAL SUPPLY
• Power supply and wiring
The power supply to the premises must meet the minimum requirements of the unit being installed, with special
attention given to the supply current, cable size and MCB recommendation. The supply voltage to the appliance
must never drop below 207 Volts.
Important
The electrical supply requirements:-
The 9 KW and 12 KW boilers meet the requirements of EN 610000-3.3
The 9 KW and 12 KW boilers must be installed in premises having a service supply of ≥100A
per phase.
The 12 KW boiler must be installed in premises having a system impedance of not more than 0.1939 + J 0.1939Ω
WARNING: This boiler must be earthed
WARNING: Means for disconnection must be incorporated in the fixed wiring in accordance
with the wiring rules
WARNING: Electrical work must be carried out by a person competent to do so
All system components shall be of an approved type.
The electrical installation shall be in accordance with the current rules in force in the countries of
destination at the time of installation.

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2.1.5 Electrical supply
Means of disconnection of the electrical supply to the boiler must be incorporated in the fixed
wiring in accordance with the wiring rules.
Two isolators are required, one for the 24hr supply, and the other for the interrupted supply (off
peak if available)
Means of disconnection of the 24hr supply should be by a double pole switched fused spur box (fuse
rating 3 amp), having a minimum contact separation of 3mm in each pole. The fused spur box should
be readily accessible and adjacent to the appliance. It should be identified as to its use.
Means of disconnection should not be fitted in a room containing a fixed bath or shower. The 24hr mains
supply cable and other cables for external controls must be heat resistant and flexible PVC type of at
least 0.75mm2 (24/ 0.20mm)
Means of disconnection of the interrupted supply (off peak) should be by a double pole switched
(60amp isolator with a 40 amp MCB Type C for the TH9/ model) and a switched (60 amp isolator with a
50 amp MCB Type C for the TH12/ model), having a minimum contact separation of 3mm in each pole.
The switched isolator should be readily accessible and adjacent to the appliance. It should be identified
as to its use.
Means of disconnection should be readily accessible and adjacent to the appliance. It should be
identified as to its use.
The interrupted mains supply cable must have a cross sectional area of at least (10mm² for the
TH9/ model) and (16mm² for the TH12/ model). The mains supply cable from the isolator to the
boiler should be preferably encased by flexible conduit.
2.1.6 Heating system controls
The heating system should have installed: A timer and room thermostat or a programmable room
thermostat controlling the central heating system.
Thermostatic radiator valves should be installed in addition to the room thermostat for better economy
and energy saving.
2.2.1 Boiler Position
The boiler must be installed in accordance with the rules in force in the countries of destination. This
boiler is not suitable for fitting outside.
Any electrical switch must be positioned so that it cannot be touched by a person using the bath or
shower.
The boiler must be positioned on a level base or floor which is sufficiently robust to take its weight,
(Refer to table 1, “Data”)
If the location of the boiler or any part of the system is subject to severe cold weather conditions, it is
recommended that a frost thermostat is fitted. Any part of the system that may be vulnerable to freezing
must be protected.

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2.2.2 Boilers in a compartment
Where the installation of the boiler will be in an unusual position, the current issue of BS 6798 gives
detailed guidance on these requirements.
An existing cupboard or compartment modified for the purpose may be used, providing minimum
clearances are maintained. Details of essential requirements for cupboards or compartment design are
given in the current issue of BS6798.
The doorway opening should be of sufficient size to allow for easy removal of the boiler.
Where the boiler is fitted in a cupboard or compartment permanent ventilation is not required.
Compartment ventilation is required to dissipate heat from any external heating circuit pipe-work, to
prevent overheating of the electrical components and wiring.
Any existing compartment air vents must not be removed or blocked off.

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Diagram 2.2.3 - Clearances
2.2.3 Clearances
front
The boiler should be positioned so that at least the minimum
operational and servicing clearances are provided, see diagram
2.2.3 additional clearances may be required around the boiler for
installation. A clearance of 600mm is required at the front of the
boiler for maintenance and installation.
820mm
Thermaflow
Unit
2.3.1 General notes
The boiler is intended for use in a sealed system only.
750mm
2.3.2 Safety valve
600mm
The safety relief valve is an integral part of the boiler. It cannot
be adjusted but has a manual test device.
2.3.3 Pressure Gauge
A pressure gauge is incorporated into the boiler to indicate the system pressure.
The gauge has a cold fill set pointer.
2.3.4 Pump
14
The circulation pump is integral with the boiler. Diagram 2.3.5
2.3.5 Expansion vessel
Expansion
Vessel
The TH9/210U & TH12/210U and TH9/250 & TH12/250U are both supplied
with an expansion vessel with a capacity of 25 litres and the TH9/330U &
TH12/330U is supplied with a 35 litre expansion vessel. If the system water
content exceeds the maximum quoted in table 1, [Data] an additional vessel
should be connected into the system as close as possible to the central
heating return connection of the boiler. Ref. Diagram 2.3.5 Thermaflow ®
The charge pressure shall not be less than the static head at the point of connection, which is the
height of the top point of the system above the expansion vessel.
2.3.6 By- pass
An automatic by- pass valve should be incorporated in the system for maximum system
efficiency. (A By-Pass MUST be fitted on all models).
2.3.7 Filling sealed systems
The boiler has a filling loop incorporated within it, and pressure gauge to register the fill pressure.
There must be no permanent connection to the mains water supply; even though a non return valve is
supplied. Disconnect filling loop and seal both valves with suitable caps.
2.3.8 Corrosion inhibitor
The maintenance of sufficient concentration of corrosion inhibitor in your Thermaflow system is vital to
prevent corrosion. We would recommend sentinel X100, or equivalent. Dose appropriately according to
the size of the Thermaflow and central heating system volume combined.

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2.3.9 Draining
A draining tap must be provided at the lowest points of the system, which will allow the entire
system to be drained. The boiler has two drain taps fitted to it one for primary and one for
secondary.
2.4. Domestic hot water system
2.4.1 General
The domestic hot water service must be in accordance with the rules in force in the countries of
destination.
2.4.2 Water pressure
For the minimum and maximum, working pressures of the domestic hot water circuit of the boiler refer
to (“data” table 1).
If the cold water inlet pressure exceeds 400 KPA (4 Bar) a pressure reducing valve must be
fitted to the inlet to the boiler.
2.4.3 HOT WATER FLOW RATE
The boiler is capable of flow rates of 20-30 litres per/min @ 40ºC ∆t (depending on model). Hot
water flow rate and pressure will be determined by the volume and pressure of the incoming cold water
supply.
2.4.4 Hard water areas
In areas where the water is “Hard” more than 200 mg / Litre, it is recommended that a proprietary scale
reducer is fitted in the cold water supply to the boiler. Consult the local water authority for additional
advice.
A double check valve assembly must be fitted upstream of the scale reducer, for the relative position of
the scale reducer and pressure reducing valve, if required, refer to the manufacturers instructions.
2.5. Installation, PREPARATION [water connections]
2.5.1 Water connections
See General Data Diagram 1.8.1 & table 1.8.1 for pipe work connections
It is recommended to flush out the domestic water and heating system before connecting to the boiler.
While making the connections, do not subject any of the connections to heat as you may
damage the seals.
2.5.2 Safety valve discharge
It must not discharge above an entrance or window or any type of public access.
The position of the Tundish (if required when the pressure relief pipe is not visible to
atmosphere) shall be visible to the occupants and shall be positioned away from any electrical
devices.

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The position of discharge pipes (Tundish) drain valves and motorised valves etc, must be
positioned away from electrical components.
The water may drip from the discharge pipe of the pressure-relief device and must be left open
to the atmosphere.
The pressure relief device must be operated regularly to remove lime deposits and to verify that
it is not blocked.
The discharge pipe connected to the pressure-relief device must be installed in a continuously
downward direction and in a frost free environment.
The connection for the discharge is made at the bottom side of the safety relief valve. A tundish
should be fitted by the installer (if required) in accordance with G3 of the current building
regulations.
This must be extended, using not less than 15mm O.D. metal pipe, to discharge, in a visible position,
outside the building, facing downwards, preferably over a drain. The pipe must have a continuous fall and
be routed to a position so that discharge water, possibly boiling or steam, cannot create any danger to
persons, damage to property or external electrical components and wiring.
2.6 Electrical Installation Requirements
• Power supply and wiring
The power supply to the premises must meet the minimum requirements of the unit being installed, with special
attention given to the supply current, cable size and MCB recommendation. The supply voltage to the appliance
must never drop below 207 Volts.
Important
The electrical supply requirements:-
The 9 KW and 12 KW boilers meet the requirements of EN 610000-3.3
The 9 KW and 12 KW boilers must be installed in premises having a service supply of ≥100A
per phase.
The 12 KW boiler must be installed in premises having a system impedance of not more than 0.1939 + J 0.1939Ω

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2.6.1 SUPPLY
The boiler requires two separate ~230-240V power supplies. A (24HR) supply for controls and an
interruptible supply for the boiler. (Off Peak power supply if it is available).
The off peak or interruptible mains supply is wired according to the following diagram 2.6.1, from the 63
amp double pole isolator by way of flexible 16mm² cable into the main terminals in enclosure marked
No. 3 on the boiler schematic diagram 1.8.1, see diagram 2.6.1 below.
Diagram 2.6.1
17
L
N
E
Supply
*
*
*
*25mm2COLOUR CODED METER TAILS
CONNECT TO METER / TELE-SWITCH
60A Double Pole
Isolating switch
with 50A Type C
MCB located at
meter or consumer
unit
60A Double Pole
Isolating switch
with 50A Type C
MCB located
adjacent to
Thermaflow
L
N
E
THERMAFLOW
TERMINALS
Cable Sizing
Boiler Rating Minimum Cable Size ~230-240V-50Hz, (8,250-9,000w - 10mm²) and (11,000-12,000w –
16mm²). MCB MUST BE TYPE C

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2.6.2
The mains supply into the enclosure marked No 21 on the boiler diagram should be wired to the 24HR
supply via 3 Amp fused isolating switch located at the boiler, ref. diagram 2.6.2a.
Diagram 2.6.2a
18

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Diagram 2.6.2b
2.6.3 External Controls
External heating controls should be connected to the terminals marked R1 & R2 shown in diagram
2.6.2b. All external controls should be connected to terminals marked R1 & R2 in the enclosure marked
No 22 in the boiler schematic diagram 1.8.1.
WARNING: ALL EXTERNAL CONTROLS MUST NOT BE TAKEN FROM ANY OTHER
POWER SUPPLY OTHER THAN VIA THE
3 AMP FUSED ISOLATING SWITCH MENTIONED ABOVE.
19

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20
Electrical Connections
2.6.4 Supply cable connection [24 HR Supply]
Caution: To prevent an induced current from switching the central heating on when not required it is
important that the heating system control cables are separated from the other mains cables.
There is provided 2 heat resistant cables extending from the enclosure situated between both circulating
pumps. One cable has 3 cores. Live, Neutral and earth to be connected to a 3 amp double pole fused
isolator. The other cable has 2 cores coloured brown and (blue core covered with brown sleeve) these are
both common live and switched live wires to be connected to external heating controls.
The boiler requires a permanent mains supply through an external isolator (rated to 3amp) which must
isolate any heating system controls see diagram 2.6.2b
Any heating system controls must not interrupt the permanent mains supply to the boiler.
Standard colours are Brown- Live, Blue- Neutral and Green and yellow- Earth. Make the earth cable of a
greater length so that if the cable becomes strained the earth would be the last to become
disconnected.
CAUTION: IT IS ESSENTIAL TO MAKE SURE THAT THE POLARITY IS CORRECT.
2.6.5 Heating system controls
All external controls and wiring are required to provide a minimum of reinforced insulation at 250 vrms
between the parts of those devices operating at mains hazardous voltage and the user accessible parts
of those devices.
Note: for further information, see the building regulations 1991- conservation of fuel and power, 1995
edition- appendix G, table 4B.
When any kind of external heating system controls are being used to regulate the heating system
connect a single pole type, to the appropriate terminals of the connector shown in diagram 2.6.2b, or (to
the 2 core cable provided).
If the installation requires protection by a “Frost Thermostat” connect a single pole type, to the
appropriate terminals of the connector shown in diagram 2.6.2b.
2.6.6 Electrical Test
Carry out preliminary electrical system checks as below.
1) Test insulation resistance to earth of mains cables.
2) Test earth continuity and short circuit of all cables.
3 Test the polarity of the mains.
4 Refit the enclosure cover.