Heatrae Sadia ELECTROMAX SOLAR Release note

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ELECTROMAX SOLAR
INSTALLATION & SERVICING INSTRUCTIONS

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CONTENTS
SECTION PAGE
1.0 INTRODUCTION 3
2.0 TECHNICAL SPECIFICATION 9
3.0 INSTALLATION 11
4.0 COMMISSIONING 34
5.0 USER DEMONSTRATION 49
6.0 MAINTENANCE 50
7.0 FAULT FINDING 54
8.0 PART REPLACEMENT 57
9.0 SPARES 71
10.0 ACCESSORIES 75
11.0 GUARANTEE 76
12.0 ENVIRONMENTAL INFORMATION 76
13.0 COMMISSIONING & SERVICING RECORDS 77
14.0 SPARES STOCKISTS 80

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1.0 INTRODUCTION
Thank you for purchasing a Heatrae Sadia Electromax Solar. The Electromax Solar is
manufactured in the UK to the highest standards and has been designed to meet all the latest
relevant safety specications.
1.1 IMPORTANT POINTS
The Electromax Solar must be installed and commissioned by a competent person. Please read
and understand these instructions before installing the Electromax Solar. Following installation
and commissioning, the operation of the Electromax Solar should be explained to the user and
these instructions left with them for future reference.
The Electromax Solar 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 the use of the appliance by a person responsible
for their safety.
Children should be supervised to ensure they do not play with the Electromax Solar.
The Electromax Solar domestic hot water cylinder is of unvented type. Its installation is subject
to Building Regulation G3 (England and Wales), Technical Standard P3 (Scotland) or Building
Regulation P5 (Northern Ireland). Installation must be carried out by a competent person.
Electrical installation must be carried out in accordance with the current IEE Wiring
Regulations.
The Electromax Solar electric heating boiler must be installed into a sealed (pressurised) primary
system. Following installation the primary system should be ushed in accordance with BS 7593
and an inhibitor added.
The Electromax Solar does not contain any substances harmful to health; it does not contain
any asbestos.

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1.2 PRODUCT DESCRIPTION
The Electromax Solar is available in a number of capacities and congurations:
95 022 212 - 185 Litre, Radiator
95 022 214 - 220 Litre, Radiator
95 022 215 - 250 Litre, Radiator
95 022 312 - 185 Litre, Underoor
95 022 314 - 220 Litre, Underoor
95 022 315 - 250 Litre, Underoor
95 022 216 - 185 Litre, Radiator, East / West Array
95 022 217 - 220 Litre, Radiator, East / West Array
95 022 218 - 250 Litre, Radiator, East / West Array
95 022 316 - 185 Litre, Underoor, East / West Array
95 022 317 - 220 Litre, Underoor, East / West Array
95 022 318 - 250 Litre, Underoor, East / West Array
The Electromax Solar, when combined with a suitable Electromax Solar Collector kit, comprises
all the principle components to provide:
An efcient solar thermal water heating system•
An electric back up water heating system•
An electric heated wet central heating system•
The Electromax Solar has an unvented domestic hot water storage cylinder manufactured
from Duplex stainless steel and insulated with polyurethane foam.
The primary heat source is solar energy. The sun’s energy is captured by a series of solar
collector panels ( supplied separately ) through which a special heat transfer uid is pumped.
As the uid passes through the collector panels its temperature is raised. The heated uid is
circulated through a heat exchanger coil in the base of the hot water storage cylinder transferring
the heat gained to the stored water, gradually raising its temperature. The cooled uid then
returns to the collector panel to be heated again.
The solar primary circuit includes a circulating pump, a ow meter, an expansion relief valve,
a manual air vent and two high temperature check valves, all factory tted. Solar collectors,
solar expansion vessel and heat transfer uid are supplied as separate accessory kits.
Temperature control of the solar circuit is provided by an electronic controller housed in the
main Electromax Solar control panel. Over-temperature protection is provided by a manually
re-settable double pole cut out.
In the UK a well designed solar system has the potential to deliver up to 60% of a dwellings hot
water requirement from solar energy, however this energy is not received uniformly throughout
the year (70% of the UK annual radiation is received over the period April to September and
25% is received in the months of June and July).

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The Electromax Solar also has two 3kW immersion heaters: a lower immersion heater to
supplement the solar energy for periods of low solar gain, and an upper immersion heater to
provide a one-hour boost.
The domestic hot water system includes a factory tted temperature and pressure relief valve
and expansion vessel. A cold water combination valve which comprises a pressure reducing
valve, expansion relief valve, check valve and strainer, is supplied loose.
The Electromax Solar has a wet, sealed, central heating primary circuit suitable for connection
to radiators or underoor manifolds depending on the model purchased. The central heating
circuit is separate to both the solar and domestic hot water systems.
The central heating heat source is a 9kW electric ow type boiler. The system includes a
circulating pump, an expansion vessel, an expansion relief valve, an automatic air vent and
an automatic bypass valve, all factory tted.
Temperature control of the central heating system is provided by a room thermostat ( supplied
loose ). Over-temperature protection of the central heating system is provided by an electronic
control housing in the main Electromax Solar control panel.
Only Electromax Solar Collector kits should be used with the Electromax Solar.
The Solar Collector kits include Solar Collectors, Solar Collector Fixing Kit, Solar Collector
Sensor, Solar Fluid, 2 Metres Flexible Stainless Steel Tube, Solar Expansion Vessel, Solar
Rated Thermostaic Mixing Valve, Installation Instructions:
95 970 517 - 1 Panel, On Roof, Slate & Tile
95 970 518 - 2 Panel, On Roof, Slate & Tile
95 970 519 - 2 Panel, On Roof, Slate & Tile , East / West Array
95 970 520 - 3 Panel, On Roof, Slate & Tile , East / West Array
95 970 521 - 1 Panel, On Roof, A Frame
95 970 522 - 2 Panel, On Roof, A Frame
95 970 523 - 1 Panel In Roof, Slate
95 970 524 - 2 Panel In Roof, Slate
95 970 525 - 1 Panel In Roof, Tile
95 970 526 - 2 Panel In Roof, Tile
95 970 527 - 2 Panel In Roof, Slate, East / West Array
95 970 528 - 3 Panel In Roof, Slate, East / West Array
95 970 529 - 2 Panel In Roof, Tile, East / West Array
95 970 530 - 3 Panel In Roof, Tile, East / West Array

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FIGURE 01: ELECTROMAX SOLAR BASIC FEATURES
REAR
LIFTING
POINTS
CONTROL
PANEL
CONTROL
PANEL
COVER
TUNDISH
VIEWING
WINDOW
CABLE ENTRY
POINTS
(RHS & LHS)
SIDE LIFTING
POINTS
(RHS & LHS)
BASE
LIFTING
POINTS
REMOVABLE
PANELS FOR
PIPE ENTRY
(RHS & LHS)
TOP VIEW
FRONT VIEW
SIDE VIEW

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FIGURE 02: ELECTROMAX SOLAR BASIC FEATURES
SOLAR FLOW
SOLAR CIRCULATING
PUMP
CENTRAL HEATING
CIRCULATING PUMP
CENTRAL HEATING
AUTOMATIC AIR VENT
CENTRAL HEATING
EXPANSION VESSEL
SOLAR PRESSURE
RELIEF VALVE
CENTRAL HEATING
PRESSURE RELIEF
VALVE
SOLAR MANUAL
AIR VENT & CHECK
VALVE
TEMPERATURE AND
PRESSURE RELIEF
VALVE
SOLAR DRAIN
CENTRAL HEATING
BYPASS VALVE
CENTRAL HEATING
DRAIN
SOLAR RETURN
DOMESTIC HOT
WATER EXPANSION
VESSEL
SOLAR FLOW
METER
ELECTRIC BOILER
BOOST IMMERSION
HEATER
LOWER IMMERSION
HEATER
HOT WATER
OUTLET
SOLAR THERMAL
CUT-OUT
COLD WATER
INLET
FILLING LOOP
TUNDISH
CENTRAL HEATING
ISOLATION VALVES
SOLAR CHECK
VALVE
HOT WATER
CYLINDER
CABLE ENTRY
(SOLAR SENSOR &
DIVERTOR VALVE)

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1.3 STORAGE, HANDLING AND UNPACKING
The Electromax Solar is delivered in protective expanded polystyrene packaging with reinforced
corner posts. The assembly is shrInk wrapped in heavy duty polythene. The Electromax Solar
accessory kit is supplied boxed inside the Electromax Solar underneath the top panel. The
packaging must be removed prior to installation. It is recyclable and should be disposed of in
accordance with environmental guidelines.
The Electromax Solar must be stored upright, under cover in dry conditions. It must not be
stacked.
Note the weight of the product and the handling instructions applied to the packaging. If using
a handling device, eg. a sack barrow, to manually move the Electromax Solar, trucking must
be done from the rear to avoid damage to the outer panels.
The Electromax Solar should be lifted and handled by two persons. Hand holds are provided
in the rear panel, in both side panels and in the base panel to aid lifting. Stooping should be
avoided and protective clothing worn when necessary.
Note: Internal packing pieces which protect the central heating expansion vessel in transit
must be removed prior to installation.
FIGURE 03: ELECTROMAX SOLAR CONTROL PANEL
FRONT COVER
SOLAR
CONTROLLER
DOMESTIC HOT
WATER SWITCH
1 HOUR
BOOST SWITCH
FUSES
CENTRAL HEATING
PRESSURE GAUGE
SOLAR PRESSURE
GAUGE
ELECTRIC BOILER
INDICATORS
ELECTRIC BOILER
TEMPERATURE
ADJUSTER
HOT WATER CENTRAL HEATING SOLAR CONTROLLER
RIGHT
DOWN
UP
LEFT
OFF
ON BOOST
OFF
ON
ALARM
HEAT
CALL
SUPPLY
TEMP
S’CON CH’PUMP R’STAT -+

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1.4 COMPONENT CHECK LIST
Within the Electromax Solar packaging the following components are supplied. Please check
that all parts are available before commencing installation.
• Electromax Solar
• Cold water combination valve
• Programmable room thermostat
• Immersion heater key spanner
• Hose connection adaptor for primary system drain valve
• Set of cable entry glands and blanking plugs (5 x 20mm, 1 x 25.4mm)
• Installation manual
• User instructions
• Fitting template
Warranty card•
Divertor valve ( East/West models only )•
2.0 TECHNICAL SPECIFICATIONS
2.1 GENERAL
Capacity (Total) 185 litre 220 litre 250 litre
Capacity (Solar) 65 litre 75 litre 80 litre
Weight (Empty) 94kg 105.5kg 112kg
Weight (Full) 279kg 325.5kg 362kg
Height 1580mm 1800mm 1990mm
Width 550mm 550mm 550mm
Depth 600mm 600mm 600mm
2.2 DHW CYLINDER
Rated pressure 0.6 MPa (6 bar)
Operating pressure 0.35 MPa (3.5bar)
Supply pressure 0.15 MPa min (1.5bar) – 1.6 MPa max (16bar) max at
PRV
Temp’ & pressure relief valve 1.0 MPa (10bar) / 90ºC
Pressure reducing valve 0.35 MPa (3.5bar)
Expansion relief valve 0.6 MPa (6bar) Fitted in Cold Water Combination Valve
Expansion vessel capacity 18 litre
Expansion vessel pre charge 0.35 MPa (3.5bar)
Check Valve Fitted in Cold Water Combination Valve
Strainer Fitted in Cold Water Combination Valve
Coil heat exchanger Stainless Steel tube, Ø25mm, 1.1m² surface area
Lower immersion heater 3kW 825 alloy sheathed element (curved)
Upper immersion heater 3kW 825 alloy sheathed element (straight)
Thermostatic control 10 – 70°C rod type thermostats
Over temperature Control 85ºC manually re-settable double pole cut out

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2.3 SOLAR CONTROLLER & SOLAR PRIMARY CIRCUIT
Rated pressure 1.0 MPa (10bar)
Operating pressure 0.2 – 0.4 MPa (2 - 4bar)
Pressure relief valve 0.6 MPa (6 bar)
Expansion vessel capacity 24 litres (supplied separately)
Expansion vessel pre charge 0.35 MPa ( 3.5bar) (supplied separately)
Flow meter 2 – 15 litre/min
Air vent Manual type, tted
Check valves x2 tted
Circulating pump Grundfos UPS 15-50
Heat transfer uid Glycol / Water 40/60 mix (supplied separately)
Thermostatic control Electronic controller
Over temperature control 85ºC manually re-settable double pole cut out
2.4 ELECTRIC BOILER & CENTRAL HEATING PRIMARY CIRCUIT
Rated pressure 0.3 MPa (3bar)
Operating pressure 0.1 MPa (1bar)
Pressure relief valve 0.3 MPa (3bar)
Expansion vessel capacity 12 litres
Expansion vessel pre charge 0.1 MPa (1bar)
Automatic bypass valve ` 0.05 MPa (0.5bar)
Automatic air vent Fitted
Circulating pump Grundfos UPS 15-50
Electric boiler 9kW Electric ow type
Thermostatic Control Electronic Controller: Radiator 65 ºC - 80 ºC
Underoor 30 ºC - 60 ºC
Over temperature Control 85ºC manually resettable double pole cut out
2.5 CYLINDER PERFORMANCE
TABEL 01:
MODEL AUXILIARY
VOLUME
HEAT UP TIME
- AUX (MINS)
HEAT UP TIME -
BOOST (MINS)
STANDING HEATLOSS
kWhr/24hr
185 120 126 60 1.76
220 145 152 60 1.73
250 170 178 60 1.70
Heat up time is based on raising the auxillary volume from 15ºC to 60ºC using the lower 3kW
immersion heater.
Boost Volume = 57 Litres
Heating times using solar primary circuit will be variable as they will depend on the amount of
solar radiation, sunshine hours, collector panel type, size and orientation.

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3.0 INSTALLATION
3.1 INSTALLATION - GENERAL
It is recommended that installation of the Electromax Solar is carried out in the following
order:
Location•
Domestic Hot Water•
Solar•
Central Heating•
Electrical•
3.2 PANEL REMOVAL
Installation will require removal of the panels:
TOP PANEL - Unscrew the two screws located on the top face, about two thirds of the•
way back, pull panel towards you and lift up.
LOWER FRONT PANEL - Pull the panel forward.•
FRONT PANEL - Remove the lower front panel. Unscrew the two screws located either•
side at the bottom of the front panel and pull the panel forwards.
FRONT INSULATION - Remove front and lower front panel and pull front insualtion piece•
away from pipework manifolds.
CONTROL PANEL - Remove top panels, front panels and front insulation piece. Unscrew•
the two screws located either side at the top of the control panel and allow the control
panel to drop forwards.
CONTROL PANEL REAR COVER - Open the control panel. Unscrew the two screws•
located either side of the control panel rear cover and remove the rear cover.
TOP
PANEL
TOP PANEL
SCREWS
FRONT
PANEL
FRONT
PANEL
SCREWS
LOWER
FRONT
PANEL CONTROL PANEL
CONTROL PANEL
SCREWS
REAR COVER
REAR COVER
SCREWS
FIGURE 04: PANEL REMOVAL
FRONT
INSULATION

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3.3 INSTALLATION - LOCATION
The Electromax Solar must not be sited outside or in any location where it could be exposed
to the weather. It must be installed in a dry and frost free environment.
It must be vertically mounted on a at, level surface capable of supporting its full weight when
full of water.
Sufcient access must be allowed around the Electromax Solar to allow for removal of the
top and front panels, and for servicing and maintenance (see gure 05).
Consideration should also be given to the location of:
COLD WATER INLET - this can be from underneath the Electromax Solar or through•
knock out panels at the front, bottom on the right hand side. Connection is made by 22mm
compression tting.
COLD WATER COMBINATION VALVE - this must be installed in the incoming mains•
supply.
HOT WATER OUTLET- this can be from underneath the Electromax Solar or through•
knock out panels at the front, bottom on the right hand side. Connection is made by 22mm
compression tting.
HOT WATER DISCHARGE - discharge pipe runs are required from the Temperature and•
Pressure Relief Valve on the Electromax Solar and the Expansion Relief Valve on the
Cold water Combination Valve.
SOLAR COLLECTORS - connections are made at the back, top left hand side of the•
Electromax Solar by 22mm compressions ttings.
SOLAR EXPANSION VESSEL - the solar expansion vessel should be sited as close to the•
Electromax Solar as possible, allowing sufcient access for servicing and maintenance.
SOLAR DIVERTOR VALVE - the solar divertor valve ( East/West models only ) should be•
sited as close to the Electromax Solar as possible, allowing sufcient access for servicing
and maintenance.
SOLAR EXPANSION RELIEF - a container to hold solar uid discharge should be sited •
as close to the Electromax Solar as practicably possible. A pipe run from the Solar Relief
Valve to the container needs to be installed.
CENTRAL HEATING CONNECTIONS - these can be from underneath the Electromax•
Solar or through knock out panels at the front, bottom on the left hand side. Connection
is made by 22mm compression ttings.
ROOM THERMOSTAT - the room thermostat is wall mounted. Provision to route the wiring•
back to the Electromax Solar must be allowed for.
CABLE ENTRY POSITIONS - Cable entry can either be made from the front, top right or•
left hand side of the Electromax Solar.

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FIGURE 05: CONNECTION POINTS AND CLEARANCE DISTANCES
CABLE ENTRY
POINTS
(RHS & LHS)
REMOVABLE
PANELS FOR
PIPE ENTRY
(RHS & LHS)
DISCHARGE
PIPE
COLD
WATER
INLET
HOT
WATER
OUTLET
SOLAR FLOW SOLAR RETURN
CENTRAL
HEATING
FLOW
CENTRAL
HEATING
RETURN
SOLAR
DISCHARGE
50mm SIDE
CLEARANCE
MINIMUM
50mm SIDE
CLEARANCE
MINIMUM
300mm TOP
CLEARANCE
MINIMUM
CABLE ENTRY (SOLAR
SENSOR & DIVERTOR VALVE)
50mm FRONT
CLEARANCE MINIMUM
TOP VIEW
FRONT VIEW
SIDE VIEW

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3.4 INSTALLATION - DOMESTIC HOT WATER
Installation of the domestic hot water system requires:
Check mains water supply•
Connection to cold water supply•
Installation of the cold water combination valve•
Installation of the solar rated thermostatic mixing valve•
Connection to hot water outlets•
Installation of discharge pipework from the Temperature & pressure relief valve and•
expansion relief valve.
3.4.1 WATER SUPPLY
The mains water supply to the property will be supplying both the hot and cold water require-
ments simultaneously. It is recommended that the maximum water demand be assessed and
the water supply be checked to ensure this demand can be satisfactorily met.
A high mains water pressure will not always guarantee high ow rates. Wherever possible
the mains water supply pipe should be in 22mm copper pipe or 25mm blue MDPE pipe. The
minimum mains water supply requirements should be 1.0 bar (dynamic) and 20 litres per
minute ow rate. At these values outlet ow rates may be poor if several outlets are used
simultaneously, the higher the available pressure and ow rate the better the system perform-
ance will be.
The Electromax Solar unvented cylinder has an operating pressure of 3.5 bar which is controlled
by the cold water combination valve. The cold water combination valve can be connected to
a maximum mains supply pressure of 16 bar.
FIGURE 06: DOMESTIC HOT WATER SCHEMATIC
CYLINDER
EXPANSION
VESSEL
TEMPERATURE
AND PRESSURE
RELIEF VALVE
EXPANSION
RELIEF VALVE
PRESSURE
REDUCING
VALVE
CHECK
VALVE
TUNDISH
TUNDISH
MAINS
WATER
SUPPLY
HOT WATER
OUT
COLD WATER
COMBINATION VALVE
BALANCED COLD
WATER SUPPLY
THERMOSTATIC
MIXING
VALVE
DRINKING
WATER
SUPPLY

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The water supply must be of wholesome water quality (uid category 1 as dened by the water
supply regulations 1999). In some areas of the UK the water supply may have a high level
of natural hardness. Whilst this is not detrimental to the quality of the water, in water heating
systems the calcium carbonate which causes the water’s “hardness” can precipitate onto
hot surfaces and in time adversely affect hot water performance. If the temporary hardness
of the cold water mains supply exceeds 200mg/l (check with your Water Supply Company)
it is recommended that some form of water treatment is considered. Any device selected
must be suitable for use in unvented water heating systems and not unduly affect the ow
rate capacity to the Electromax Solar cylinder, consult the manufacturer of the device for
details.
3.4.2 CONNECTION TO THE COLD WATER SUPPLY
Connection to the cold water supply can be from underneath the Electromax Solar or through
knock out panels at the front, bottom right hand side.
Connection is made by 22mm compression tting.
Solder connections directly to the unit must not be made as the heat may damage the
Electromax Solar insulation materials. Damage caused by heat applied to solder ttings in
close proximity to the unit will not be covered by the warranty.
Solder connections may be used elsewhere in the system away from the Electromax Solar.
Use water soluble ux for making soldered joints and ensure any ux residue is removed
following installation
3.4.3 COLD WATER COMBINATION VALVE
EXPANSION VALVE
COLD MAINS
CONNECTION (22mm)
EXPANSION VALVE
OUTLET (15mm)
OUTLET CONNECTION
(22mm)
PRESSURE REDUCING
VALVE HOUSING
PRESSURE REDUCING
VALVE CARTRIDGE (3.5bar)
FIGURE 07: COLD WATER COMBINATION VALVE

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The cold water combination valve can be connected anywhere on the cold water mains
supply prior to the Electromax Solar. Whilst it is often more convenient to do so, there is no
requirement to site the valve close to the Electromax Solar, it can be located at a point remote
from the Electromax Solar if this is more convenient. However, ensure the discharge from the
expansion relief valve can be correctly installed. The expansion relief valve connection must
not be used for any other purpose
The cold water combination valve is installed as a complete one-piece unit. The valve
incorporates an isolating valve, a pressure reducer, a strainer, an expansion relief valve and
a single check valve. The cold water combination valve can be tted in any orientation to
suit the installation, however, ensure the valve is installed with the direction of ow arrows
(stamped on the side of the brass body) pointing towards the Electromax Solar.
NOTE: No other valve should be tted between the Cold Water Combination Valve and the
Electromax Solar cold inlet.
3.4.4 BALANCED COLD WATER SUPPLIES
It is advantageous in many mixer showers or taps to have balanced hot and cold water
pressure. In these instances the balanced cold water supply should be teed off the supply to
the Electromax Solar immediately after the cold water combination valve.
Branches to cold outlets where drinking water may be drawn should be taken directly from
the main supply before the Cold Water Combination Valve to avoid the possibility of warm
expanded water being drawn from cold taps.
3.4.5 CONNECTION TO HOT WATER OUTLET
Connection to the hot water outlet can be from underneath the Electromax Solar or through
knock out panels at the front, bottom right hand side. Connection is made by 22mm
compression tting.
Solder connections directly to the unit must not be made as the heat may damage the
Electromax Solar insulation material. Damage caused by heat applied to solder ttings in
close proximity to the unit will not be covered by the warranty.
3.4.6 SOLAR THERMOSTATIC MIXING VALVE
It is recomended that hot water outlets are supplied via a solar rated thermostatic mixing valve
(supplied with the Heatrae Sadia Electromax Solar Colelctor kits).
The solar rated thermostatic mixer valve is connected as follows:
Inlet marked ‘HOT’ connected to Electrommax Solar hot outlet•
Inlet marked ‘COLD’ connected to balanced cold water supply•
Outlet marked ‘MIX’ connected to hot water outlets•
Connectionsaremadeby22mmcompression󰘰ttings.
The pipework from the thermostatic mixing valve to the hot outlet ttings should be in 22mm
pipe with short runs of 15mm pipe to showers and basins. Small bore pipe can be used to
suit some taps, but runs should be kept as short as possible. Pipe sizes may vary due to
system design.

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3.4.7 PIPEWORK, FITTINGS AND OUTLET / TERMINAL FITTINGS
All pipework, ttings and terminal ttings must be compatible with unvented systems and
have a rated operating pressure of at least 6 bar. Where plastic pipe / ttings are being used
the rated pressure must be achievable at outlet temperatures that can be expected within the
hot water distribution pipework. If in doubt, consult the manufacturer of the ttings selected.
3.4.8 SECONDARY CIRCULATION
Secondary circulation is not recommended for the Electromax Solar as it is intended for off
peak electrical operation. Circulating the stored water would gradually cool the Electromax
Solar to an unacceptable temperature during off peak periods.
FIGURE 08: SOLAR THERMOSTATIC MIXING VALVE
ELECTROMAX
SOLAR
BALANCED COLD INLET
ELECTROMAX SOLAR
HOT OUTLET
MIXED HOT OUTLET
HOT
COLD
MIX
SOLAR RATED
THERMOSTATIC
MIXING VALVE

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3.5 INSTALLATION DISCHARGE
It is a requirement of Building Regulations that any discharge from an unvented system
should be visible and safely conveyed away from the system without danger to persons in
or about the building where it is installed. The discharge pipe should be tted in accordance
with the requirements and guidance notes of Building Regulations. Building Regulation G3
Requirements and Guidance section 3.9 are reproduced in the following sections.
Information Sheet No.33 available from the British Board of Agrement gives further advice on
discharge pipe installation. For discharge pipe arrangements not covered by G3 Guidance or
BBA Info sheet No. 33 advice should be sought from either your local Building Control Ofcer
or Heatrae Sadia. The discharge pipework supplied tted to the Electromax Solar will convey
any discharge from the unvented cylinder Temperature and Pressure Relief Valve and the
sealed system Pressure Relief Valve. A discharge pipe will also be required from the Expansion
Valve tted to the Cold Water Combination Valve. Where practical this can be teed into the
discharge pipe from the Electromax. It is recommended that an additional tundish is tted into
this discharge pipe to give an early indication of operation of the Expansion Valve.
In some instances it may be possible to discharge into an internal waste system and soil stack.
To do this a self sealing waste valve must be tted into the discharge pipe after the tundish
to prevent foul odours or back-pressurisation from the waste system entering the building via
the tundish. In these systems it is essential that the tundish is tted in a visible position as the
nal point of discharge will not be visible. Consult the manufacturer’s recommendations with
respect to the correct tting, orientation and waste and soil stack materials selection. It will also
be necessary to get dispensation from your local Building Control Ofcer to discharge in this
manner. Discharges from an unvented system can be up to 95oC for several minutes, ensure
any waste or soil pipe connected to the discharge can safely accept these conditions.
G3 REQUIREMENT
“…there shall be precautions…to ensure that the hot water discharged from safety devices
is safely conveyed to where it is visible but will not cause danger to persons in or about the
building.”
Water may drip from the discharge pipe of the pressure-relief device and that this pipe must
be left open to the atmosphere.
The pressure-relief device is to be operated regularly to remove lime deposits and to verify
that it is not blocked.
The discharge pipe connected to the pressure relief device is to be installed in a continuously
downward direction and in a frost free environment
G3 GUIDANCE SECTION 3.9
The discharge pipe (D1) (see gure 8, page 19) from the vessel up to and including the tundish
is generally supplied by the manufacturer of the hot water storage system. Where otherwise,
the installation should include the discharge pipe(s) (D1) from the safety device(s). In either
case the tundish should be vertical, located in the same space as the unvented hot water
storage system and be tted as close as possible and within 500mm of the safety device e.g.
the temperature relief valve.

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The discharge pipe (D2) from the tundish should terminate in a safe place where there is no
risk to persons in the vicinity of the discharge, preferably be of metal and:
a. Be at least one pipe size larger than the nominal outlet size of the safety device unless its
total equivalent hydraulic resistance exceeds that of a straight pipe 9m long i.e. discharge
pipes between 9m and 18m equivalent resistance length should be two pipe sizes larger,
and so on. Bends must be taken into account in calculating the ow resistance. Refer to
table 2 and the worked example.
b. Have a vertical section of pipe at least 300mm long below the tundish before any elbows
or bends in the pipework.
c. Be installed with a continuous fall.
d. Have discharges visible at both the tundish and nal point of discharge, but where this is
not possible or is practically difcult there should be clear visibility at one or other of these
locations.
An alternative approach for sizing discharge pipes would be to follow BS6700:1987 Specication
for design, installation, testing and maintenance of services supplying water for domestic use
within buildings and their cartilages, appendix E, section E2 and table 21.
Examples of acceptable discharge arrangements are:
i. Ideally below a xed grating and above the water seal in a trapped gully.
ii. Downward discharges at low level; i.e. up to 100mm above external surfaces such as car
parks, hard standings, grassed areas etc. are acceptable 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.
iii. Discharges at high level; e.g. into a metal hopper 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 3m from any plastics guttering system that would
collect such discharges (tundish visible).
iv. Where a single pipe serves a number of discharges, such as in blocks of ats, the number
served should be limited to not more than 6 systems so that any installation discharging
can be traced reasonably easily. The single common discharge pipe should be at least one
pipe size larger than the largest individual discharge pipe (D2) to be connected. If unvented
hot water storage systems are installed where discharges from safety devices may not be
apparent i.e. in dwellings occupied by blind, inrm or disabled people, consideration should
be given to the installation of an electronically operated device to warn when discharge
takes place.
Note: The discharge will consist of scalding water and steam. Asphalt, roong felt and non-
metallic rainwater goods may be damaged by such discharges.
Worked example of discharge pipe sizing:
The example below is for a G1/2 temperature relief valve with a discharge pipe (D2) having
4 No. elbows and length of 7m from the tundish to the point of discharge.
From Table 2:
Maximum resistance allowed for a straight length of 22mm copper discharge pipe (D2)•
from a G1/2 temperature relief valve is 9.0m.
Subtract the resistance allowed for 4 No. 22mm elbows at 0.8m each = 3.2m•

20
Therefore the permitted length equates to: 5.8m•
5.8m is less than the actual length of 7m therefore calculate the next largest size.•
Maximum resistance allowed for a straight length of 28mm pipe (D2) from a G1/2•
temperature relief valve equates to 18m
Subtract the resistance of 4 No. 28mm elbows at 1.0m each = 4.0m•
Therefore the maximum permitted length equates to 14.0m•
As the actual length is 7m, a 28mm (D2) copper pipe will be satisfactory.•
TABLE 02:
Valve outlet
size
Minimum size of
discharge pipe
D1
Minimum size of
discharge pipe
D2 from tundish
Maximum resistance
allowed, expressed as
a length of straight pipe
(i.e. number of elbows
or bends)
Resistance created
by each bend.
G1/2 15mm 22mm
28mm
35mm
up to 9m
up to 18m
up to 27m
0.8m
1.0m
1.4m
G3/4 22mm 28mm
35mm
42mm
up to 9m
up to 18m
up to 27m
1.0m
1.4m
1.7m
G1 28mm 35mm
42mm
54mm
up to 9m
up to 18m
up to 27m
1.4m
1.7m
2.3m
Fixed grating
Discharge below
fixed grating
(Building Regulation
G3 section 3.9d gives
alternative points
of discharge)
Trapped
gully
Discharge pipe (D2) from tundish,
with continuous fall. See Building
Regulation G3 section 3.9d i-iv,
Table 4 and worked example
300mm
minimum
500mm maximum
Metal discharge pipe (D1) from
Temperature relief valve to tundish
Tundish
Safety device
(e.g. Temperature
relief valve)
FIGURE 09: DISCHARGE PIPE ARRANGEMENT