Horstmann CentaurStat 7 User manual

Electronic 7
Installation Instructions
The Horstmann Electronic 7 is an advanced water heating control, which can be
programmed to take advantage of cheap night-rate electricity, so that there is a tank
of hot water available for the morning.
1
INSTALLATION AND CONNECTION SHOULD ONLY BE CARRIED OUT BY A
SUITABLY QUALIFIED PERSON AND IN ACCORDANCE WITH THE CURRENT
EDITION OF THE IET WIRING REGULATIONS.
WARNING : ISOLATE MAINS SUPPLY. BEFORE COMMENCING INSTALLATION
ENSURE THE UNIT IS PROPERLY EARTHED.
The Electronic 7 is supplied with its own surface mounting box, which can also be
mounted over a single or double gang flush wall box. It should NOT be mounted on
an unearthed metal surface. Means of disconnection from the supply having at least
3mm contact separation in both poles must be incorporated in the fixed wiring.
Horstmann recommends a separate fused circuit from the consumer unit (24 Hour
supply) protected by a 15 amp HRC fuse or, preferably, a 16 amp MCB. In some
cases immersion heater failure can damage the ELECTRONIC 7. Installation of a
100 mA RCD will provide additional protection for the unit. If the ELECTRONIC 7 is
to be connected to a ring main then the spur feeding the controller should be
protected in the same way.

Mounting
The Electronic 7 should be removed from the mounting box by unscrewing the 2
captive screws securing the
unit.
Conduit Box Mounting
Use either holes marked 'A' in
Fig.1 to secure to a single gang
box, or the two holes marked
'C' for a double gang box.
Cable entry is through the cut-
out between the 2 fixing holes
'A'.
Surface Mounting
Use the two holes marked 'B' in
Fig. 1 Cable entry is through
the most appropriate cut-out
REMOVE THE APPROPRIATE CABLE ENTRY CUT-OUTS BEFORE FIXING THE
BOX, WHERE POSSIBLE DRILL THE BOX TO PROVIDE A CLOSE FITTING
ENTRY FOR CABLES AND HEAT-RESISTANT FLEXIBLE CORDS. TAKE CARE TO
REMOVE SHARP EDGES .
Connections
Use a three-core cable with a minimum
conductor size of 1.0mm for a 2kW heater, or
1.5mm for a 3kW heater to connect the unit to
the supply. Connect the incoming wires to the
terminal block as follows;
TERMINAL 1 - LIVE in
TERMINAL 2 - NEUTRAL in
TERMINAL 3 - NEUTRAL(s) out to immersion
heater(s)
TERMINAL 4 - LIVE out to Boost immersion
heater
TERMINAL 5 - LIVE out to Off-Peak immersion
heater
Clamp all surface wiring adjacent to the box or
use trunking where appropriate. Secure the
heat resistant flexible cords from the immersion
heaters using the cable clamp in the box.
Link terminals 4 & 5 when using
a single immersion heater
2

Single Element Immersion Heaters
The 3 core flexible cord should be heat-resistant and rated to 85°C.
TERMINAL 4 (Boost live output) should be connected to TERMINAL 5 (Off-Peak
live output) and to the immersion heater.
The Neutral connection should go to TERMINAL 3 and the Earth connection to the
EARTH TERMINALS.
Dual Element Immersion Heaters
The elements should be controlled through separate thermostats. In practice the
thermostat for the top (short) element is usually set 5-10°C less than the thermostat
for the long Off-Peak element. The 3 core flexible cords should be heat-resistant
and rated 85°C.
TERMINAL 4 (boost live output) should be connected to the short element and
TERMINAL 5 (Off-Peak live output) to the long element.
The Neutral connections should go to TERMINAL 3 and the Earth connection to the
EARTH TERMINALS.
Twin Immersion Heaters
The thermostat for the top immersion element should be set lower than the
thermostat for the bottom immersion heater.
The 3 core flexible cords should be heat-resistant and rated 85ºC. TERMINAL 4
(boost live output) should be connected to the top immersion heater and TERMINAL
5 (off-peak live output) to the bottom immersion heater. The two Neutral connections
should go to TERMINAL 3 and the Earth connections to the EARTH TERMINALS.
When wiring is complete ensure that all terminal screws, including the earth terminal
screws are securely tightened to achieve a minimum torque of .75Nm.
Commissioning Instructions
3
The commissioning switch is on the rear of the unit (once removed from
the back box) and must now be set to achieve the correct operation of the
controller and to engage the BATTERY RESERVE. The display will remain
blank with the switch in the “OFF” position.
It is essential that the correct commissioning switch position is selected. Incorrect
setting of the commissioning switch may result in inefficient use of the available off-
peak supply. On installation the installer needs to select whether the Electronic 7 will
switch at GMT times throughout the year or whether the timings need to alter as the
clocks change.

For example:
GMT/BST – Switching time will be changed by one hour. In the GMT/BST mode the
clock display will match the actual switching time.
GMT ONLY – Switching will always take place at GMT times (summer and winter).
The clock display will tell the correct time of day.
If Connection is to be made where a 2-Rate electricity meter is controlled by a Radio
Teleswitch or other equipment which control tariffs remotely or seasonally, it is
essential that before setting the commissioning switch you find out how the off-peak
times are controlled.
The Customer Service Centre of your Electricity Supplier will confirm information
regarding Off-Peak electricity timing and the switching method used for your area.
On installations where the 2-Rate electricity meter is controlled by a mechanical
Tariff Timeswitch the commissioning switch should be set to GMT ONLY.
Time Display
The Electronic 7 is fitted with an automatic clock that is pre-set on manufacture and
should not normally require any adjustments by the user.
The clock will automatically adjust the time to Summertime (BST) or Wintertime
(GMT) as appropriate and this setting is always shown on the clock display.
No adjustment is needed to be made by the installer/user.
TIMED RUN SUMMER
WINTER
TIMED BOOST
CLOCK
BOOST PROGRAMME
OFF PEAK PROGRAMME
AM
Resetting The Unit
Sometimes electronic equipment can become scrambled or frozen. To overcome
this you should reset the unit.
This can be achieved by holding down the buttons marked “BOOST, MINUS, PLUS
& SELECT” simultaneously.
The clock should now be adjusted to the correct time of day by following Setting
Time of Day on page 5.
4

Press the green
“SET” button
until the
indicator on
the left hand
side of the
screen is next
to “CLOCK”.
Setting Time of Day
Adjust the hour
by pressing
the white
“MINUS” or
“PLUS”
buttons. Once
you are happy
with the hour
selected, press
the blue
“SELECT”
button.
The minutes
will now flash.
To adjust the
minutes you
need to once
again press the
“MINUS” or
“PLUS”
buttons.
Once you are
happy with the
time selected,
press the blue
“SELECT”
button, this will
now take it
back to the
“RUN” position
on the left
hand side of
the screen.
Setting Off-Peak Heating Periods
Press the green
SET button until
the indicator on
the left hand
side of the
screen is next to
“OFF PEAK
PROGRAMME”
The hour will now
flash for the 1st on
time, this can be
adjusted by pressing
the “MINUS” and
“PLUS” buttons.
Once you are happy
with the hour you
have selected press
the “SELECT” button
This will then make
the minutes flash,
which can be
adjusted by pressing
the “MINUS” and
“PLUS” buttons as
required. Once you
are happy with the
minutes, press the
“SELECT” button to
take you to the 1st
off time
Use the “MINUS” and “PLUS”
buttons to adjust the hour. When you
are happy with the hour selected
then press the “SELECT” button
which shall now take you to the
minutes. Press the “MINUS” and
“PLUS” buttons to SELECT the
minutes you require and once you
are happy with the minutes press the
“SELECT” button.
The hour will be
flashing on the 2nd on
time, if this is not required
then press
the green “SET” button
which will take you back
to the main screen.
If your electricity tariff offers multiple off peak periods then the 2nd and 3rd off peak
periods should be set up by repeating the above procedure. Should you not require
any further off-peak settings ensure that the remaining periods are set at the same
time. For example; 2nd On 12:00pm - 2nd Off 12:00am; 3rd On 12:00am - 3rd Off
12:00pm (These are de-fault settings).
5

Default Time Settings
Default Times
1st ON 1st OFF 2nd ON 2nd OFF 3rd ON 3rd OFF
2:15am 7:15am 12:00pm 12:00am 12:00am 12:00pm
After re-setting the unit the off-peak heating times will revert back to the default
factory settings, these are shown above, however if you wish to change these times
please proceed as instructed in the SETTING OFF-PEAK HEATINGS PERIODS
part of this manual on page 5.
Completing The Installation
To assemble the controller to its mounting box, first push the connectors numbered
1-5 into the corresponding numbered terminal as shown in Fig.1
Carefully offer the controller to the box and secure with the fixing screws, ensuring
the wiring does not become damaged.
Switch on the mains supply and put the rocker switch in the TIMED position.
Questions
(Q) There is no display on the screen?
(A) Ensure there is mains supply getting to the unit and that the battery switch on the
rear of the unit is in either the GMT / BST or GMT ONLY position.
(Q) The display has become frozen?
(A) This could be due to local electrical interference. Using the RESET procedure in
this manual may rectify the fault.
(Q) How do I change the back-up battery?
(A) The back-up battery is integral to the unit and will save the settings for at least
two years if the power is disconnected. The battery is NOT replaceable and any
attempt to remove it will invalidate the warranty.
6

Specification
Electrical
Purpose of Control Electronic Immersion Heater Control for E7
Tariffs
Contact Rating 13A Amp 230V AC
(Suitable for Emmersion Heaters up to 3kW)
Contact Type Micro-disconnection
Switch Type Rocker switch, double-pole micro-disconnection
Supply 230V AC 50Hz only
Protection Class I
Control Action Type 1B,R
Operating Time Limitation Intermittent
Software Class Class A
Battery Type Lithium
Battery Life 2 Years
Display Custom LCD, Backlit
Clock 12 hour AM/PM
Display Time Adjustment 1 Minute Intervals
Switch Time Adjustment 1 Minute Steps
Programme Selection Off-Peak, 3 periods per day.
Programmable Boost & 1 Hour Manual Boost
Mechanical
Dimensions 170mm x 115mm x 60mm
Case Material Thermoplastic, flame retardant
o
Ball Pressure Test Temperature 75 C
Mounting Custom surface mounted back
box,.Independantly mounted
Environmental
Impulse Voltage Rating Cat III 4000V
Enclosure Protection Ip30
Pollution Degree Degree 2
o o
Operating Temperature Range 0 C to +35 C
Compliance
Design Standard EN 60730-2-7 RoHS
BEAB Approved
7

Part Number P83080 Issue 3
South Bristol Business Park,
Roman Farm Road, Bristol BS4 1UP
t: [phone]
e: [email protected]
www.horstmann.co.uk