andrews 32/143 User manual

NATURAL GAS
FIRED STORAGE
WATER HEATERS
HI-FLO RANGE
Models
32/143, 65/173,
81/264, 62/341,
54/418, 54/440
Permanent Pilot,
Auto Ignition
with Flue Damper
‘E’/‘F’ Series
STANDARD RANGE
Models
24/39, 32/40, 40/61,
63/62, and 84/87
Permanent Pilot,
Auto Ignition ‘G’ Series
INSTALLATION
GUIDE,
OPERATION
AND SERVICE
MANUAL
T H I S M A N U A L M U S T B E K E P T W I T H T H E A P P L I A N C E
April 2007 Part No. E132

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© Copyright Andrews Water Heaters 2007
Reproduction of any information in this publication by any method is not permitted
unless prior written approval has been obtained from Andrews Water Heaters.
Andrews Storage Water Heaters have been designed and manufactured to comply
with current International standards of safety. In the interests of the health and
safety of personnel and the continued safe, reliable operation of the equipment,
safe working practices must be employed at all times. The attention of U.K. users is
drawn to their responsibilities under the Health and Safety Regulations 1993.
All installation and service on the Andrews Water Heater must be carried out by
properly qualified personnel, and therefore no liability can be accepted for any
damage or malfunction caused as a result of intervention by unauthorised
personnel.
The Andrews Water Heaters policy is one of continuous product improvement, and
therefore the information in this manual, whilst completely up to date at the time of
publication, may be subject to revision without prior notice.
Further information and assistance can be obtained from:
Andrews Water Heaters
Wood Lane, Erdington, Birmingham B24 9QP
Technical Helpline
Tel: [phone] Fax: [phone]
THE ANDREWS WATER HEATERS COVERED IN THIS MANUAL
ARE FOR USE WITH NATURAL GAS ONLY

CONTENTS
SECTION 1 GENERAL AND SAFETY INFORMATION
General Information 2
British Standards 2
Health and Safety Regulations 1993 3
Legionellae in Water Heaters 3
SECTION 2 TECHNICAL DATA
Standard Range 4
Hi-Flo Range 5
SECTION 3 INSTALLATION
Introduction 6
Draught Diverter 6
Location 6
Gas Supply 7
Electrical Supply 8
Flue Systems 10
Air Supply and Ventilation 12
Water Quality and Treatment 14
Water Connections- Hydrojet System 15
Vented Systems, Standard Range 16
Unvented Systems, Standard Range 18
Vented Systems, Hi-Flo Range 20
Unvented Systems, Hi-Flo Range 23
SECTION 4 COMMISSIONING
Standard Range 26
Hi-Flo Range 28
SECTION 5 OPERATION
Standard Range 35
Hi-Flo Range 35
SECTION 6 SERVICING
Introduction 36
Burner Assembly, Standard Range 36
Burner Assembly, Hi-Flo Range 36
Gas Control Valve, Standard Range 37
Gas Control Valve, Hi-Flo Range 37
Flue Ways 37
Cleaning the Storage Vessel 38
Magnesium Anode(s) 38
Safety Valve 38
SECTION 7 REPLACING COMPONENTS, Hi-Flo RANGE
Gas Control Valve 40
Burner 40
SECTION 8 FAULT FINDING
Permanent Pilot Models - Standard and Hi-Flo Range 41
All Models 42
Auto Ignition Models, Hi-Flo Range 43
SECTION 9 PARTS LISTS AND ILLUSTRATIONS
Standard Range 45
Hi-Flo Range 46
Unvented Systems Kit 50
24V Auto System Kit 52
PAGE

GENERAL AND SAFETY INFORMATIONSECTION 1
The Andrews Water Heater has been designed for use with NATURAL GAS only and is
manufactured to give an efficient, reliable and long service life.
To ensure the continued, trouble-free operation of your heater at maximum efficiency, it
is essential that correct installation, commissioning, operation and service procedures are
carried out strictly in accordance with the instructions given in this manual. By law,
installation and commissioning of the heater must be carried out by properly qualified
personnel.
The heater(s) must be installed in accordance with the following requirements;
The current GAS SAFETY (INSTALLATION AND USE) REGULATIONS
The current BUILDING REGULATIONS
The Water Supply (WATER FITTINGS) REGULATIONS 1999
Additionally, installation should be performed in accordance with all relevant
requirements of the Gas Supplier, Local Authority and recommendations of the British
Standards and Codes of Practice detailed below.
STANDARD RANGE
BS 6700: 1997 Specification for design, installation, testing and maintenance of
services supplying water for domestic use within buildings and their
curtilages. This standard supersedes the following British Standards
and Codes of Practice: CP99, CP310, CP324, 202, CP342 Part 2,
Centralised Hot Water Supply.
BS 5440 Installation of flues and ventilation for gas appliances of rated output
not exceeding 60kW.
Part 1:2000 Specification for installation of flues.
Part 2:2000 Specification for installation of ventilation for gas appliances.
BS 5546:1990 Installation of gas hot water supplies for domestic purposes.
BS 6891 Installation of low pressure gas pipework of up to 28mm in domestic
premises.
BS 7206:1990 Specification for unvented hot water storage units and packages.
I/M2 Purging procedures for non-domestic gas installations.
I/M5 Soundness testing procedures for industrial and commercial gas
installations.
I/M11 Flues for commercial and industrial gas fired boilers and air heaters.
I/M16 Notes on installation of gas pipework
(excluding 25mm and below).
IGE/UP/10 Pt.1
Edition 2 Installation of Gas Appliances in Industrial and Commercial Premises
Hi-Flo RANGE
As STANDARD RANGE plus:
BS 6644: Installation of gas fired hot water boilers of rated inputs between
60kW and 2MW.
NOTE: Consideration should be given to amendments or updates to the
above standards.
GENERAL
INFORMATION
BRITISH
STANDARDS
AND CODES OF
PRACTICE
2

GENERAL AND SAFETY INFORMATION SECTION 1
It is the duty of manufacturers and suppliers of products for use at work to ensure, so far
as is practicable, that such products are safe and without risk to health when properly
used and to make available to users, adequate information about their safe and proper
operation.
Andrews Water Heaters should only be used in the manner and purpose for which they
were intended and in accordance with the instructions in this manual. Although the
heaters have been manufactured with paramount consideration to safety, certain basic
precautions specified in this manual must be taken by the user.
It is imperative that all users of the heater must be provided with all the information and
instruction necessary to ensure correct and safe operation.
Water systems in buildings have been associated with outbreaks of Legionnaires' Disease,
particularly in health care facilities where occupants are significantly more susceptible to
infection.
In recognition of the risks in hospitals, a Code of Practice for the Control of Legionellae
in Health Care premises has been issued by the Department of Health (1991). Codes of
Practice applicable to other premises have been published by other organisations,
principally the Health and Safety Executive (HS)(G70) and the Chartered Institute of
Building Services Engineers (CIBSE, TM13).
All Codes of Practice draw attention to the design and operation of water systems with
reference to avoidance of factors that favour colonisation by Legionellae bacteria. These
factors include stagnation, lukewarm conditions (20ºC to 45ºC) and the accumulation of
debris, scale and corrosion in the base of tanks and calorifiers.
Andrews Water Heaters has commissioned an independent evaluation of their products
to investigate their resistance to build-up of legionellae bacteria.
Experiments were conducted to determine whether, following a substantial challenge by
legionellae pneumophilia, after overnight and stagnation conditions, the system was
rendered free from viable recoverable legionellae. It was found that at 61ºC, following a
challenge of approximately 107 organisms per litre, within one hour, more than 99.999%
of organisms had been killed. After a subsequent stagnation period, sampling did not
reveal any residual contamination. The design of the base of the water heater precludes
legionellae colonisation, even after build-up of debris. The burner positioning ensures
that the water at the bottom of the heater reaches the same, or higher temperature as in
the rest of the heater.
Based on data obtained through experiment, the Andrews Water Heater can be described
as legionellae resistant as it is considered unlikely that, at the temperature tested, the
organism would colonise the water heater and present a possible health risk.
HEALTH AND
SAFETY
REGULATIONS
1993
EFFECTIVENESS
IN COMBATING
LEGIONELLAE
3

TECHNICAL DATASECTION 2
STANDARD
RANGE
4
Storage Capacity l 109 145 182 286 382
gal 24 32 40 63 84
Recovery thro' 44ºC/80ºF l/h 178 182 278 281 397
gal/h 39 40 61 62 87
Recovery thro' 56ºC/100ºF l/h 142 146 220 227 316
gal/h 31 32 49 50 70
Heat Input Gross kW 12 12.5 19 19 26
Btu/h 40,944 42,650 65,000 65,000 88,712
Heat Input Net kW 11 11.4 17 17 24
Btu/h 37,532 38,900 58,004 58,004 81,888
Gas NATURAL CAT I2H
Burner Gas Pressure mbar 10 10 10 10 10
ins wg. 4 4 4 4 4
Max. Gas Input Pressure mbar 35 35 35 35 35
ins wg. 14 14 14 14 14
Gas Flow Rate m3/h 1.12 1.16 1.78 1.78 2.43
ft3/h 39.4 41.22 62.86 62.86 85.71
Gas Connection Rc (in BSP Int) 1/2 1/2 1/2 1/2 1/2
Flue Gas Temp. ºC 200 205 195 160 125
Flue Gas Volume m3/h 17 18 26 31 37
Gas Injector Orifice Diameter mm 2.95 3.05 3.86 3.86 4.22
in 0.116 0.120 0.152 0.152 0.166
Flue Size (Secondary) mm 100 100 100 125 125
in 4 4 4 5 5
Cold Water Feed Connection R (in BSP/Exl) 1 1 1 1 11/4
Hot Water Flow Connection R (in BSP/Exl) 1 1 1 1 11/4
*Return Connection Rp (in BSP/Int) 3/4 3/4 3/4 3/4 3/4
Drain Port Size R (in BSP/Ext) 3/4 3/4 3/4 3/4 3/4
Max. Working Pressure bar 10.3 10.3 10.3 10.3 10.3
lbf/in2150 150 150 150 150
Max. Test Pressure bar 20.6 20.6 20.6 20.6 20.6
lbf/in2300 300 300 300 300
Weight Empty kg 43 57 65 110 181
lb 94 126 144 244 400
Weight Full kg 151 202 247 396 562
lb 334 446 544 874 1240
Shipping Weight kg 44 59 68 120 194
lb 98 131 150 264 428
Shipping Dimensions Depth mm 546 587 587 692 914
in 211/2 231/8 231/8 271/4 36
Shipping Dimensions Width mm 486 537 537 651 762
in 19 1/8 21 1/8 21 1/8 25 5/8 30
Shipping Dimensions Height mm 1194 1245 1499 1575 1829
in 47 49 59 62 72
ANDREWS MODEL NO. 24/39 32/40 40/61 63/62 84/87

TECHNICAL DATA SECTION 2
5
Storage Capacity l 145 295* 368* 282* 245* 245
gal 32 65 81 62 54 54
Recovery thro' 44ºC/80ºF l/h 649 786 1199 1549 1900 1998
gal/h 143 173 264 341 418 440
Recovery thro' 56ºC/100ºF l/h 517 629* 959 1239* 1520* 1598*
gal/h 114 138 212 273 334 352
Recovery thro' 72ºC/130ºF l/h 399 484* 730 953* 1169* 1223*
gal/h 88 106 162 210 257 270
Heat Input Gross kW 42.8 50 80 102 128 139
Btu/h 146,034 170,600 272,960 384,024 436,736 474,268
Heat Input Net kW 39 45 73 93 116 126
Btu/h 133,068 153,540 249,076 317,316 395,792 430,000
Gas NATURAL CAT I2H
Burner Gas Pressure mbar 6.8 6.8 6.8 6.8 6.8 N/A
Pernament Pilot ins wg. 2.73 2.73 2.73 2.73 2.73 N/A
Burner Gas Pressure mbar 10 10 10 10 10
Auto Ignition ins wg. 4 4 4 4 4
Max. Gas Input Pressure mbar 35 35 35 35 35
ins wg. 14 14 14 14 14
Gas Flow Rate m3/h 4.0 4.68 7.44 9.48 11.94 13.14
ft3/h 141 164.76 263.58 336.24 421.98 465.06
Gas Connection Rc (in BSP Int) 3/4 3/4 3/4 3/4 3/4 3/4
Flue Gas Temp. ºC 117 140 150 195 185 215
Flue Gas Volume m3/h 62 73 116 149 186 202
Gas Injector Orifice Diameter mm 2.69 2.87 3.66 3.45 3.50 N/A
Permanent Pilot in 0.106 0.113 0.144 0.136 0.138 N/A
Gas Injector Orifice Diameter mm 2.40 2.58 3.25 3.18 N/A 3.26
Auto Ignition in 0.094 0.101 0.127 0.125 N/A 0.128
Flue Size (Secondary) mm 150 150 200 200 250 250
in 6 6 8 8 10 10
Cold Water Feed Connection R (in BSP/Exl) 11/2 11/2 11/2 11/2 11/2 11/2
Hot Water Flow Connection R (in BSP/Exl) 11/2 11/2 11/2 11/2 11/2 11/2
*Return Connection Rp (in BSP/Int) 3/4 3/4 3/4 3/4 3/4 3/4
Drain Port Size R (in BSP/Ext) 3/4 3/4 3/4 3/4 3/4 3/4
Max. Working Pressure bar 10.3 10.3 10.3 10.3 10.3 10.3
lbf/in2150 150 150 150 150 150
Max. Test Pressure bar 20.6 20.6 20.6 20.6 20.6 20.6
lbf/in2300 300 300 300 300 300
Weight Empty kg 190 200 289 257 269 269
lb 419 441 637 566 594 594
Weight Full kg 335 495 656 538 514 514
lb 738 1091 1447 1186 1134 1134
Shipping Weight kg 199 223 316 282 293 293
lb 438 492 697 623 645 645
Shipping Dimensions Depth mm 902 914 914 914 914 914
in 35 1/2 36 36 36 36 36
Shipping Dimensions Width mm 768 762 762 762 762 762
in 30 1/4 30 30 30 30 30
Shipping Dimensions Height mm 1270 1960 2083 1960 1960 1960
in 50 77 82 77 77 77
ANDREWS MODEL NO. 32/143 65/173 81/264 62/341 54/418 54/440
Hi-Flo
RANGE
* If the water heater is to be
used on an unvented system,
the combined temperature/
pressure relief valve must be
fitted directly into the tank.
The secondary return is then
connected to the drain port
via a suitable tee.

LOCATION
INSTALLATIONSECTION 3
THE LAW REQUIRES THAT INSTALLATION IS CARRIED OUT BY A
PROPERLY QUALIFIED PERSON
Installations must be carried out in accordance with Gas safety (Installation and Use)
Regulations 1998, Building Regulations, The Water Supply (Water Fittings) Regulations
1999 and any requirements of the local Gas Authority, Local Authority, Water and Fire
Authorities and the current British Standards and Codes of Practice listed in Section 1.
The fittings pack supplied with the heater contains the items listed below.
1 - Installation and Service Manual.
1 - Coupler Socket 3⁄4in BSP.
1 - Gas Cock.
1 - Drain Cock.
1 - Flue Adaptor Socket (Where required).
2 - Cap End 11⁄2in BSP (Hi-Flo only).
2 - 11⁄2in x 3in Nipples (32/143 Model only).
1 - Warranty Card.
The draught diverter must be assembled with the legs provided.
Attach the legs to the draught diverter with the nuts and bolts provided.
Fit the draught diverter (1) as shown in Fig.1 to the water heater using the screws
provided. For Standard Range fit the draught diverter to the top of the water heater
using the location holes.
In some cases, it may be necessary to drill the fixing holes in the top cover to fit the
draught diverter to the water heater. By using the draught diverter as a template,
position carefully over the flueway and mark the hole positions to be drilled 4mm.
Fit the adaptor socket (2) and caulk into the draught diverter as shown in Fig. 1.
The location selected for installation of the heater must allow the provision of a
satisfactory flue, adequate air supply, drain facilities and must be well illuminated.
A purpose built boiler room or compartment is strongly recommended.
A manual valve for isolation of the boiler room should be installed in the gas supply;
it should be clearly identified and readily accessible for use at all times.
If a purpose built boiler room is not available, measures should be taken to protect the
heater from damage and prevent any extraneous matter from being stored on or around
the heater.
See BS 6644 Clauses 4, 5 and 6 for details.
INTRODUCTION
ASSEMBLING
THE DRAUGHT
DIVERTER
Fig. 1
Draught Diverter
Assembly
6
Top Connections
81/264 Only
Elbows must be used
Top Connections
65/173

INSTALLATION SECTION 3
The heater must not be installed in any location which contains a bed, bath or shower.
There must be easy access to the boiler room and heater at all times.
A clearance of 800mm (311⁄2in) for Hi-Flo and 300mm for Standard Range should be left
at the front of the heater for removal of the burner.
Clearances at the sides and rear of the heater should be at least 305mm (12 in).
Service clearances for removal of the anodes and flue baffles should be provided as
detailed below.
STANDARD RANGE
Models 24/39, 32/40, 40/61 762mm (30 in)
Model 63/62 1143mm (45 in)
Model 84/87 1270mm (50 in)
HI-FLO RANGE
Model 32/143 597mm (231⁄2in)
Model 81/264 1300mm (52 in)
Models 65/173, 62/341, 54/418, 54/440 1143mm (45 in)
The floor on which the heater is installed must be non-combustible, flat, level and of
sufficient strength to withstand the weight of the heater filled with water (see Section 2,
Technical Data) and should satisfy the requirements of the Local Authority and Building
Regulations.
NOTE:
If the heater is in an exposed position and out of use during a period of heavy frost, it is
recommended that the whole system is drained down to prevent damage due to the
formation of ice inside the storage vessel.
THE ANDREWS WATER HEATERS COVERED IN THIS MANUAL MUST
ONLY BE USED WITH NATURAL GAS.
The installation of the gas supply must conform, depending on it's size, to the
requirements of British Standards and Codes of Practice listed in Section 1 of this manual.
A gas meter will be connected to the service pipe by British Gas plc or it's authorised
contractor.
The meter and service pipe should be checked by British Gas or it's authorised contractor
to ensure that they are adequate to deal with the gas supply to the water heater(s) in
addition to any existing or additional requirements.
Gas Supply Cock, Standard Models
Fit the gas supply cock immediately upstream of the gas control thermostat using a
suitable jointing compound and connect to the gas supply. Do not apply heat in close
proximity to the gas thermostat as damage to the control will result. A pressure test point
nipple is fitted to the gas control thermostat at the gas inlet to test the incoming gas
pressure.
LOCATION
7
GAS SUPPLY

INSTALLATIONSECTION 3
Gas Supply Cock, Hi-Flo Models
Fig 2.
Fit the gas cock immediately upstream of the gas control valve using a suitable jointing
compound and connect to the gas supply. An inlet nipple complete with pressure test
point nipple is factory fitted to the gas control valve to avoid possible damage.
Where the water heater(s) is(are) installed in a boiler house or purpose built
compartment, a manually operated valve for the boiler house must be fitted in
accordance with the Gas Safety (Installation and Use) Regulations 1998. The valve must
be easily identified and readily accessible.
After installation, the system should be pressure tested for soundness and purged in
accordance with BS 6891 or IM/2 and IM/5 as appropriate.
HI-FLO MODELS - STANDARD RANGE MODELS
External wiring to the water heater(s) must be installed in accordance with current I.E.E.
Regulations for the wiring of buildings and to any Local Regulations that may apply.
The Auto Ignition Heater is designed to operate from a 220/240V, 1Phase supply.
The fuse rating is 5 amps.
The method of connection to the mains electricity supply should facilitate complete
electrical isolation of the appliance, preferably by use of an unswitched shuttered socket
outlet in conjunction with a fused three pin plug, both complying with the requirements
of BS 1363.
Alternatively, a fused double pole switch or fused spur box serving only the heater may
be used.
The point of connection to the mains electricity supply should be readily accessible and
adjacent to the appliance.
Fig 3a and 3b.
Connect the electrical supply to the main control panel terminal block via the cable
glands in the base of the control panel. Mains input cable should be 0.75mm2, 3 core,
and should be connected to the mains supply as detailed above.
It is recommended that screen cable is used where the volt-free contacts are to be
connected from an external supply. This will eliminate the risk of possible interference
from nearby high voltage cables.
Data sheets available for Hi-Flo and Standard Range, Automatic Ignition Control System.
Contact Andrews Water Heaters.
GAS SUPPLY
ELECTRICAL
SUPPLY -
AUTO IGNITION
UNITS
8
Fig 2.
Gas Cock
BSP Thread U.P.T. Thread
Nipple
Gas Valve

INSTALLATION SECTION 3
9
Standard
Range
Hi-Flo Range
Fig 3a.
Fig 3b.
FLUE FAN
INTERLOCK 24V
REMOTE TIMER 24V
INDEPENDENT MOTOR SUPPLY
G737LGA
INTERMITTENT
PILOT IGNITION
CONTROL

INSTALLATIONSECTION 3
Detailed recommendations for flue installation are given in BS 6644, BS5440 Pt 1 and
British Gas publication IM/11 - Flues for Commercial and Industrial Gas Fired Boilers and
Air Heaters.
The flue connection is designed for BS 835 type heavy duty flue, but light quality flue
pipe, mild steel or stainless steel sheet may be used using the appropriate adapter.
Flue pipes etc. shall be fitted socket-up to keep any condensate within flue and
appliance. Flues up to 200mm (8in) diameter should be fitted with a suitable British Gas
Certified terminal.
Fig 4a.
The terminal position is most important and must be at least 1000mm (40in) above roof
surfaces or at least 600mm (24in) above any parapet and clear of any adjacent
obstruction as well as being clear of any openable windows, ventilators or features which
could allow re-entry of flue products into the building. Pressure areas should also be
avoided to prevent blowdown. See recommendations in BS 6644. BS 5440 Part 1 also
provides useful additional advice.
Flue materials, including jointing materials and fittings shall be asbestos-free, robust,
durable, corrosion resistant and non-combustible and shall comply with BS 5854 and
BS 715 or BS 4076 as appropriate, as well as being of a type accepted by the Local Gas
Authority.
When passing up through or adjacent to combustible materials, measures shall be taken
to prevent the temperature of the combustible material from exceeding 60ºC (150ºF).
The flue shall not be closer than 50mm (2in) to any combustible material except when
passing through, when it must be enclosed by a non-combustible sleeve and separated
from the sleeve by not less than 25mm (1in) air space.
Flues shall be of a size not less than specified in Section 2, Technical Data (i.e. nominal
flue size) and fitted so that there is no risk to persons in the building or from accidental
damage.
Fig 4b.
If using an existing brick chimney, it should be swept and checked for soundness before
connecting the flue and should take the shortest possible route and rise continuously to
the terminal avoiding the use of 90º bends where a change of direction is required.
Horizontal and very shallow runs of flue should be avoided since they impede the flow of
gases and increase local cooling
FLUE
SYSTEMS
10
Fig 4a.
Terminal
1000mm
40”
Minimum
Roof
Terminal

INSTALLATION SECTION 3
FLUE
SYSTEMS
11
Fig 4b.
Fig 5.
*A minimum of 600mm of vertical flue directly above the draught diverter should be
provided where possible on all natural draught flue installations. If this dimension cannot
be achieved please contact Andrews Water Heaters. Please note this is not required
where a common flue header is used on multiple installations.
Fig 5.
Common flues may be used on multiple installations only if all the heaters are of the
same burner system and fuel type and should be sized to ensure complete evacuation of
the flue products from the installation.
Where one flue is to be used more regularly or for longer periods than the others in the
group, it should be connected at the point nearest to the main flue. See BS 6644 Clause
20 for further information and recommendations on this as well as general flue
requirements.
Fit a flue clip or flange joint close to the diverter so that it is secure but can be
disconnected for servicing. The weight of the flue must be borne by securing clips, etc.
and not by the heater.
1. This flue run
must not be used
Split Flue Clip
600mm*
2 & 3 are recommended flue runs
Heater with
highest usage
fitted nearest to
main flue
(if applicable)
Each unit has an
atmospheric
burner system &
uses natural gas.

INSTALLATIONSECTION 3
AIR SUPPLY
AND
VENTILATION
12
Minimum Heights from Roof to Base of Flue Terminal
For all installations, please refer to the table below for calculating requirements. Detailed
recommendations for the air supply are given in BS 5440 Part 2, BS 6644 Clause 19
and IGE/UP/10 Pt.1.
The following notes are provided for general guidance only.
Ventilation shall prevent the heater environment from exceeding 32ºC (90ºF).
The purpose provided space in which the heater(s) are installed must have permanent air vents
communicating directly with the outside air, at high and low level. Where communication with the
outside air is possible only by means of high level air vents, ducting down to floor level for the lower
vents must be used.
For an exposed building, air vents must be fitted on at least two sides, preferably on all four sides.
Air vents should have negligible resistance and must not be sited in any position where they are likely
to- be easily blocked or flooded, or in any position adjacent to an extraction system which is carrying
flammable vapour.
Grilles or louvers should be so designed that high velocity air streams do not occur within the space
housing the heater(s).
The grilles should have a total minimum free area for the water heater(s) in addition to any other
requirements as follows:-
Where the heater is to be installed in a room the following permanent
ventilation is required:
5cm2per kW in excess of 7kW net for installations up to 54kW net.
For installations exceeding 60kW the following permanent ventilation is required:
Low Level (inlet) 540cm2plus 5cm2per kilowatt in excess of 54kW total net input.
High Level (outlet) 270cm2plus 2.5cm2per kilowatt in excess of 54kW total net input.
Where the heater is to be installed in a compartment, permanent air vents are required in the
compartment at high and low level. These air vents must either communicate with a room or
internal space or be direct to outside air.
The minimum effective areas of the permanent air vents required in the
compartment are as follows;-
Not within 1.5m (5ft) of a
vertical surface of a
structure &on the roof
Internal Route
On Ridge Not on Ridge
Pitched
Flat
Pitch
exceeding
45º
Pitch not
exceeding
45º
At or
above
ridge
level 600 mm
(24 in)
above roof
intersection
600 mm
(2 ft)
above roof
intersection
With
parapet
Not
applicable
Without
parapet
250 mm
(10 in)
above roof
intersection
The base of
the terminal
should be
600 mm
(24 in)
above the
level of the
adjacent
roof edge
The base of the
terminal should
be 600 mm
(24 in) above
the level of
the top of the
structure
1m (3.3 ft)
above roof
intersection
1m (3.3 ft)
above roof
intersection
External
Route
Internal
Route
External
Route
Type of Roof
Within 1.5m (5ft) of a
vertical surface of a
structure &on the roof
Air Vent Areas
Position of Air Vents Air from room or internal space Air direct from outside
High Level 10cm2per kW net 5cm2per kW net
Low Level 20cm2per kW net 10cm2per kW net
Note:- Both air vents must communicate with the same room or internal space or must both be on the
same wall to outside air.

INSTALLATION SECTION 3
AIR SUPPLY
AND
VENTILATION
13
IMPORTANT!
1. The effective area requirements specified in the table are related to the maximum
net input of the heater(s) and are equivalent to those specified in BS 6644 and
IGE/UP/10 Pt.1.
2. The free area of the grilles should not be less than the size of the recommended
ventilation opening.
3. The supply of air to a space housing the heater(s) by mechanical means should be:
(a) Mechanical inlet with natural extraction.
(b) Mechanical inlet with mechanical extraction.
NOTE! Natural inlet with mechanical extraction must not be used.
Where a mechanical inlet and mechanical extraction system is used, the design extraction
rate must not exceed one third of the design inlet rate.
All mechanical ventilation systems must be fitted with automatic gas shut off safety systems
which cut off the supply of gas to the heater(s) in the event of failure of either the inlet or
extract fans.
The requirements for air supply by mechanical ventilation are given in BS 6644 Clause 19.3.
and IGE/UP/10 Pt.1.
The permanent air vents shall be sited away from any extract fans. Where an extract fan is
fitted, check for spillage at the draught diverter as detailed in BS 5440 Part 1 Appendix B.
It may be necessary to increase the ventilation area to compensate for the extract fan.
4. The vapours emitted by halogen based compounds can, if drawn into the combustion
air, cause corrosion of the gas burner, thermocouple and storage vessel. Therefore, if
heaters are to be installed in locations where halogens are likely to be present, they
should be isolated from such compounds and ventilated from and to outside
uncontaminated atmosphere.
Some of the vulnerable areas are:
(a) Hairdressing salons and adjoining rooms and basements
(b) Establishments where dry cleaning solutions are used or stored.
(c) Degreasing plants using hydrocarbon solvents.
(d) Premises where refrigerant gases are used or stored.

INSTALLATIONSECTION 3
Where extreme conditions of water hardness exist, scale can form in any water heating
equipment, especially when the heater is working under conditions of constant heavy
demand and at high temperatures.
Each water heater is fitted with one or more magnesium anode(s) which protect the tank
from corrosion caused by electrolytic action. Magnesium anodes are sacrificial in that
they corrode as they protect. When the anode has eroded to less than 50% of it's
original diameter, it may not offer protection.The anodes should be inspected annually
and replaced as necessary. Frequency of anode replacement will vary dependent on water
quality.
Andrews Water Heaters offer CorrexTM UP powered anodes as an alternative to the
standard magnesium anodes. These anodes do not need maintenance or replacement.
The potentiostat which regulates the current to the CorrexTM anode, features an indicator
light which shows green to indicate correct function and red to indicate malfunction.
An additional CorrexTM BEMS version is available, which provides a remote
warning signal.
These anodes are available as an optional extra on all Andrews heaters.
In hard water areas, scale formation can occur in hot water systems and hot water
heaters and the higher the temperature and volume of water used, the more problematic
the scale build-up can be. Water treatment is normally recommended when the hardness
reaches 100 - 150ppm (7 - 10 degrees Clark) and above. This problem can be minimised
by reducing the water temperature in the heater and by fitting suitable water pre-
treatment equipment.
When installing Andrews Water Heaters in hard water areas we would recommend
that a water treatment specialist is consulted.
The following companies have supplied water treatment equipment in the UK for a
number of years to various establishments including those where Andrews water heaters
have been installed.
WATER
QUALITY AND
TREATMENT
14
WATER TECHNOLOGY LTD
Powke Lane Ind. Estate
Blackheath
Birmingham
B65 0AH
Contact
Gareth Morris
Tel: [phone]
Fax: [phone]
LIFF INDUSTRIES LTD
Bay Hall
Miln Road
Huddersfield
West Yorkshire HD1 5EJ
Contact
Ingrid Ashman
Tel: [phone]
Fax: [phone]
HYDROTEC (UK) LTD
Hydrotec House
Potts Place
West Street
Marlow
Buckinghamshire SL7 2LY
Contact
Mark Darvill
Tel: [phone]
Fax: [phone]
HYDROPATH (UK) LTD
2 Lenton Business Centre
Lenton Boulevard
Nottingham NG7 2BY
Contact
Glyn Appleby
Tel: [phone]
THE ENERGY SHOP
Thames House
89 St Leonards Road
Windsor
Berkshire SL4 3BZ
Contact
Patrick McCart
Tel: [phone]
Fax: [phone]
ECO SYSTEMS
Po Box 330
Walton on Thames
Surrey KT12 5YU
Contact
James Christie
Tel: [phone]

INSTALLATION SECTION 3
WATER
CONNECTIONS
15
Hydrojet System
The upper “jet
ports” direct the
flow outward to
begin the dynamic
mixing action.
The lower “jet
ports” direct the
flow inward to
increase the
turbulence.
The heater is fitted with the Hydrojet Total Performance System incorporated in the cold
inlet dip tube. The tube is designed to increase turbulence and reduce sediment build up,
reduce thermal stacking and increase delivery.
Mini
Hydrojet Inlet Nipple
(Side Cold Inlet
Connection)
All models now incorporate the
new Mini Hydrojet system on
cold inlet side connections.
This system ensures water is
directed onto the tank base
which minimises sediment build
up from day one of installation.
Heater Casing
Tank