Publication No. 5105703
19
2.9.
Set Overheat Thermostat Bulb
Position
Ensure that the system change-over switch
in the control box is correctly set e.g. for
GRAVITY DHW system or FULLY PUMPED
system. See Fig. 1.
If the boiler is to be used on a GRAVITY
DHW system the bulb of the overheat
thermostat must be repositioned as shown
in Fig. 21. To do this loosen the plastic
retaining screw and withdraw the thermostat
bulb from its pocket.
Position the bulb as illustrated and secure it
by finger tightening the plastic screw. Do not
over-tighten.
2.10. Electrical Connections
The boiler and all external control circuit
wiring must be supplied from the same
single isolating switch or plug and socket,
and should be fused at 3A.
Care must be taken to ensure that all wiring
to the boiler is kept clear of sharp edges and
hot surfaces.
The boiler terminal block which is situated in
the control box is not designed to accept
wiring from all the on site controls and
therefore the installer will usually need to
incorporate a suitable junction box. This
may not be required if a Potterton Electronic
Programmer is used as this incorporates a
junction box. The principle of wiring is shown
in Fig. 22.
Remove control box securing screw and
lower the control box to gain access to the
boiler terminal block.
Gravity DHW
Position
Fully Pumped
System Position
PRF0025A
Securing Screw
PRF0026A
PRF0024A
EXTERNAL
ELECTRICITY
SUPPLY
PROGRAMMER
ROOM AND/OR
CYLINDER
THERMOSTAT
CONTROL
VALVES
ETC.
BOILER
PUMP
EXTERNAL
ISOLATOR
SWITCH
4 OR 6 Core
3 Core
3 Core
4 OR 5 Core
5 OR 8 Core
4 Core
JUNCTION BOX
Installation
Fig. 21
Fig. 22
Fig. 23
