Electrical - Worcester 50/70 Installation And Servicing Instructions

10. Electrical

(See Figs. 10 to 12).
10.1 The wiring between the appliance and the electrical supply
shall comply with current IEE Wiring Regulations and any local
regulations which apply.
10.2 To gain access to the electrical terminal strip.
1. Isolate the mains electrical supply.
2. Remove the cabinet front panel by pulling forwards to
release the ball studs.
3. Pull the thermostat control knob forwards to remove from
its spindle.
4. Undo the facia retaining screws and remove the plate.
10.3 Mains Wiring
Mains supply - 230 / 240 V AC ~ 50 Hz 5A External Fuse.
LIVE - Brown, NEUTRAL - Blue, EARTH - Green/Yellow
2
Mains Cable: 0.75mm (24 x 0.20mm) to BS 6500 Table 16.
The method of connection to the appliance must allow complete
isolation of the appliance, preferably via a double pole isolator
with a contact separation of 3 mm in all poles supplying the
boiler and controls only.
The mains supply cable should be connected into the terminals
marked L (Live), N (Neutral) and E (Earth) on the appliance
terminal strip and securely held in the cable clamp located in the
right-hand side of the electrical tray base. To secure the cable,
remove the clamp retaining screw and pull its inner body out to
allow the cable to be fed through. With the cable in position refit
the screw and fully tighten to grip the cable. Feed the cable
between the side panel and the boiler insulation jacket and route
to the connection point avoiding any hot surfaces.
The appliance must be earthed.
Fig. 10. Wiring Diagram (Standard).
Mains
High limit
supply
5 Amp
thermostat
230/240V
50Hz
Brown
(C)
(1)
Control
thermostat
1 2 3 4 5 6 7 8
E
Satronic
control box
10.4 Programmer (See Fig. 11 and 12).
A time clock or programmer may be added to the control
system. A two channel programmer will allow independent
control of the central heating and hot water. However, it must be
noted that the programmer used must be suitable for gravity
feed applications when used as shown in Figs. 11 and 12, such
that the hot water channel is always on when the central
heating channel is on, otherwise the boiler will not fire when
there is a central heating demand.
10.5 Safety Check
In the event of an electrical fault after the installation of the
appliance, the electrical system shall be checked for short
circuits, fuse failure or incorrect polarity of connections.
10.6 Basic Control (Room Thermostat) (See Fig. 11).
As supplied the hot water and central heating circuits are
controlled by the boiler thermostat. Additional control may
be obtained by the use of a room thermostat. The boiler will
remain hot when there is no demand via the room
thermostat.
10.7 Off On No Demand (Room and Cylinder Thermostat)
(See Fig. 12).
This control system allows the boiler to cool when both the
cylinder and room thermostats are de-energised. The boiler
control thermostat must be set to a temperature above that of
the cylinder thermostat for the control system to function
correctly.
10.8 Frost Protection (See Fig. 11 and 12).
For full frost protection a single pole double switch
thermostat should be fitted so that both the boiler and the
circulating pump circuits are energised under frost
conditions. A suitable frost thermostat is manufactured by
SOPAC Ltd.
Plug-in
connector
Brown Brown
1
Green/Yellow Green/Yellow
2
Blue Blue
N
Brown Brown
L
Green/Yellow Green/Yellow
E
3
E
Brown
Burner
control
9
10
Manual reset
overheat
thermostat