A.O. Smith DURA-Power DRE-52 Guide

HOT WATER STORAGE DEVICES
United Kingdom / Ireland
MODELS DRE 52
DRE 80
DRE 120
INSTALLATION AND USER INSTRUCTIONS

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Read this manual carefully
Warning
Read this manual carefully before using the device. Not reading this manual and not
following the instructions in this manual may lead to personal injuries and damage to the
device.
Copyright © 2009 A.O. Smith Water Products Company
All rights reserved.
Nothing from this edition may be copied, reproduced and/or made public by means of
press, photocopying or in any other way without the prior written permission of A.O. Smith
Water Products Company.
A.O. Smith Water Products Company reserves the right to change the specications as
mentioned in this manual.
Trademarks
All brand names mentioned in this manual are registered trademarks of the respective
suppliers.
Liability
A.O. Smith Water Products Company does not accept any liability for claims of third parties
as a result of incompetent use other than mentioned in this manual and in conformity with the
General Terms and Conditions as led with the Chamber of Commerce.
For further information see the General Terms and Conditions. These can be obtained
from us free of charge.
Although utmost care has been taken in ensuring a correct and, where necessary,
complete description of the relevant parts, the manual may contain errors and some things
may be unclear.
Should you still discover faults or things which are unclear, please inform us about this. It
helps us to further improve the documentation.
Additional information
If you have any remarks or questions concerning specic subjects related to the device,
please do not hesitate to contact:
A.O. Smith Water Products Company
P.O. Box 70
5500 AB Veldhoven
The Netherlands
Telephone: (free) 0870 - AOSMITH
0870 - 267 64 84
General: [phone]
Fax: [phone]
E-Mail: [email protected]
Website: www.aosmithinternational.com
For problems with respect to connections to electricity and water supplies, please contact
the supplier/installation engineer of your installation.
Note: “A.O.Smith Water Heaters” is tradingname of Advance Services (Sales) Ltd.Reg.

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TABLE OF CONTENTS
1. GENERAL........................................................................................... 4
1.1 Device Description............................................................................................ 4
1.2 Regulation and Safety ..................................................................................... 5
1.2.1 Boil Dry Protection ............................................................................................ 7
1.2.2 Checking the Float Switch ................................................................................ 8
1.3 Technical description ........................................................................................ 9
1.4 Technical Data ................................................................................................ 10
2. FOR THE INSTALLER .....................................................................12
2.1 Installation procedures.................................................................................... 12
2.1.1 General Installation......................................................................................... 12
2.1.2 Water Connections ......................................................................................... 12
2.1.3 Electrical Connection ..................................................................................... 12
2.1.4 Electrical Diagrams......................................................................................... 13
2.2 Putting into operation...................................................................................... 17
2.2.1 Filling the Device ............................................................................................ 17
2.2.2 Putting Into Operation..................................................................................... 17
2.2.3 Putting out of Operation.................................................................................. 17
2.2.4 Temperature Regulation ................................................................................. 18
2.3 Maintenance ................................................................................................... 18
2.3.1 Sacricial anode ............................................................................................. 18
2.3.2 Descaling ........................................................................................................ 18
2.4 Steps When There is a Fault .......................................................................... 18
2.4.1 Water Temperature Not Good......................................................................... 19
2.4.2 Presumed Water Leakage .............................................................................. 19
2.4.3 Fault Table ...................................................................................................... 20
2.5 Spare Parts..................................................................................................... 20
3. FOR THE USER ...............................................................................21
3.1 Instructions for Use......................................................................................... 21
3.1.1 Filling the Device ............................................................................................ 21
3.1.2 Putting into operation...................................................................................... 21
3.1.3 Use ................................................................................................................. 21
3.1.4 Putting out of operation................................................................................... 22
3.2 Maintenance ................................................................................................... 22
3.3 Faults .............................................................................................................. 22
4. WARRANTY ..................................................................................... 23
4.1 General Warranty............................................................................................ 23
4.2 Tank Warranty................................................................................................. 23
4.3 Conditions of installation and use ................................................................... 23
4.4 Exclusions....................................................................................................... 24
4.5 Extent of the warranty..................................................................................... 24
4.6 Claims............................................................................................................. 24
4.7 No obligations for A.O. Smith other than those specied here. ...................... 24

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1. GENERAL
1.1 Device Description
The structure and equipment for this
electrical heating device are in accordance
with the European standard for electrical
household devices (EN 60335-1:2002
+ A11:2004 + A1:2004 + A12:2006
+ A2:2006 en EN 60335-2-21:2003
+ A1:2005) The device thus meets
the European Directive for Electrical
Household Devices and has the right to
bear a CE mark.
The device is suitable to be used with
an operating pressure of up to 8 bar
(= 800 kPa). The tank is made of steel
plate, which has a glass lined coating
on the inside. The tank is also provided
with two sacricial anodes to give extra
protection against corrosion. A thick CFC
free polyurethane insulation layer, covered
with a steel casing, prevents unnecessary
heat loss. The device is fully lled with
water and continually starts under water
pipe pressure. When hot water is drawn off
from the device, it is immediately topped
up with cold. Incoloy heating elements are
used for good transfer of heat.
To create extra comfort in case of long
pipelines, circulating piping with a
circulating pump may be connected to
the piping. The circulating pipeline can be
connected to the cold-water supply.

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Fig. 1 - regulation and safety
1.2 Regulation and Safety
For clarication see the diagram below:
(the image is an extract from the electrical
diagram further on)

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3 relays (3) and a control current
transformer (5) are fed from the main
connection block (1). The main circuit
is protected by 30 Amp T fuses.
The transformer (400V to 24V) is
primarily secured with T0,2 A (4). A boil
dry protection mechanism (in the form of
a oat switch) (7) is included in the 24V
current control circuit. (The oat switch
is indicated diagrammatically. See boil
dry protection further on for more precise
explanation) The control current circuit is
closed if there is water in the device (oat
switch). In this case an auxiliary relay (6)
is used which in turn switches the relay
(3). The relays determine whether the
electrical elements are fed.
The elements are fed via the relay (3).
The wire goes to the maximum thermostat
(8) via the relays (2). The maximum
thermostat has a reset button. The output
from the maximum thermostat goes to the
regulating thermostat (9). The element
(10) is fed from the regulating thermostat.
During normal operation the regulating
thermostat (9) switches the element (10)
on and off. If a temperature of above
93°C occurs on an element the maximum
thermostat (8) locks the element. In order
to put the element back into operation the
reset button of the maximum thermostat
must be pressed in. The temperature
must have dropped by approximately
20°C before the maximum thermostat can
be reset.
If the temperature of the water above in
the tank exceeds 98°C for any reason,
the combined temperature and pressure
safety device (T&P valve) will open.
The safety control circuit will be interrupted
if the water level drops to below the oat
switch (7) or if the device is switched on
while empty.
The device is then switched off completely.
This is to prevent the elements coming
into operation while there is insufcient
water present in the device (boil dry
protection).
The safety fuses, 30 Amp T for 600 V can
be ordered retrospectively from A.O. Smith.

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1.2.1 Boil Dry Protection
Fig. 2 - oat switch
The boil dry protection mechanism
consists of a oat switch which monitors
the water level approximately halfway
up the tank above the elements. If there
is insufcient water present in the tank,
then the oat (1) hangs down. If the tank
is lled with water then the oat is moved
upwards by the water. In the electrical
diagram the oat switch is reproduced
diagrammatically. The actual process
is as follows: the oat arm moves a
magnet with respect to the reed-contact
(2) which is located in the black plastic
tube at the end of the oat switch. The
movement of the magnet changes the
magnetic eld and the reed-contact is
closed.
The exposure height (3) of the reed
contact is very important.
This is 14 mm. This setting may not
be changed!
Explanation:
With an exposure height of 14 mm the
switch point is approximately halfway
along the stroke of the oat.
If the exposure height is set lower, then
the switch point shifts upwards. If the
exposure height is too small the contact
will no longer connect even if the oat
is completely above it. In this case the
device will not come into operation.
If the exposure height is set lower than
14 mm , then the switch point shifts
downwards. This means that the contact
will already connect upon a small
upwards movement of the oat. If the
exposure height is set too high then the
contact is permanently closed and the
safety mechanism does not work. This
means that the elements can come into
operation without there being sufcient
water present in the device. This will lead
to the elements burning out in a very
short time and short circuit and leakage.
So never change the exposure height.
The reed contact and the oat must
always be vertical. The arrow on the
clamping plate on the front must point
upwards. The oat switch is secured in
the tank with nut (5). By loosening nut
(4) the oat switch can be set vertically.
Nut (4)
is sealed with an o-ring with respect to
nut (5). The oat switch must be taken
out of the device as a complete unit
for checking or replacement. (The oat
cannot be passed through the opening in
nut (5).) For this purpose the device thus
has to be drained.

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1.2.2 Checking the Float Switch
Switch off the feed voltage and remove
the fuses from the elements. In this
way the control circuit can be tested
without the elements being put into
operation. Drain the device until the
water is denitely below the oat switch.
If desired the oat switch can now be
removed for visual inspection. Check
the resistance of the contacts with a
multimeter and check whether the switch
point is situated approximately halfway
along the stroke of the oat. (For new
contacts this resistance is between 1
and 1.5 Ohms). Screw the oat switch
back into the tank and place it vertically.
Check the exposure height. Close the
door and connect the feed voltage. The
safety relays must not come in. (The
tautening and release of the safety
relays is clearly audible.) Now allow
water to ow into the device. If the water
presses the oat upwards, the oat
switch closes the control circuit and the
safety relays will tauten. Then drain the
device once again. The lowering of the
water level will lead to the oat switch
blocking the control circuit once again
and the safety relays will release. Repeat
this operation at least one time.
Switch off the feed voltage and t the
fuses of the elements again. Close the
door and reconnect the feed voltage.

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1.3 Technical description
Fig. 3 - Measurements
Measurement Description 52 80 120
AHeight hot water connection 1460 1580 1600
BHeight of upper side of device 1420 1540 1570
DDiameter of boiler 560 640 750
EDepth 690 790 910
MHeight of drain valve 125 125 125
RHeight cold water supply 125 125 125
SHeight T&P connection 1230 1335 1380
1Cold water connection 1¼”-14NPT 1¼”-14NPT 1¼”-14NPT
2Hot water connection 1¼”-14NPT 1¼”-14NPT 1¼”-14NPT
3T&P connection ¾”-14NPT ¾”-14NPT ¾”-14NPT
4Drain plug connection ¾”-14NPT ¾”-14NPT ¾”-14NPT
All measurements are in mm (rounded up to 5mm).

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1.4 Technical Data
Type DRE 52-9 DRE 52-18 DRE 52-36
Tank capacity litres 200 200 200
Number of elements - 3 3 6
Power 380V-3F kW 7.6 15.2 30.3
Power 400V-3F kW 8.4 16.8 33.6
Power 414V-3F kW 9.0 18.0 36.0
Heating time up to 60C*
(400/414V) min 83/78 42/39 21/19
Heating time up to 40C*
(400/414V) min 50/47 25/23 12/12
Tap capacity 1st hour 60°C**
(400/414V) litres 329/339 467/486 741/781
Tap capacity continuous 60°C**
(400/414V) litres/hour 145/155 289/310 578/619
Tap capacity 1st hour 40°C**
litres 549/565 778/810 1235/1300
Tap capacity continuous 40°C
litres/hour 241/258 482/516 963/1032
Weight kg 73 73 73
Type DRE 80-9 DRE 80-18 DRE 80-36 DRE 80-54
Tank capacity litres 300 300 300 300
Number of elements - 3 3 6 9
Power 380V-3F kW 7.6 15.2 30.3 45.5
Power 400V-3F kW 8.4 16.8 33.6 50.4
Power 414V-3F kW 9.0 18.0 36.0 54.0
Heating time up to 60C*
(400/414V) min 125/116 62/58 31/29 21/19
Heating time up to 40C*
(400/414V) min 75/70 37/35 19/17 12/12
Tap capacity 1st hour 60°C**
(400/414V) litres 425/435 563/582 837/876 1112/1170
Tap capacity continuous 60°C**
(400/414V) litres/hour 145/155 289/310 578/619 867/929
Tap capacity 1st hour 40°C**
litres 709/725 938/970 1395/1460 1853/1951
Tap capacity continuous 40°C
litres/hour 241/258 482/516 963/1032 1445/1548
Weight kg 110 110 110 110