25
7. Replace the back of control
panel and complete the electrical
connection procedure from
paragraph 2 of Section 8.1.
Refer to the User's Operating
Instructions provided with the boiler
for the operation and setting of the
programmer.
8.3 Connect The Power Supply
(Boiler House models only)
It is recommended that the boiler should
be connected to a switched mains power
supply from an external programmer or
control system. Fit and connect the dual
thermostat control as follows:
1. For 26/36 and 36/46 models – First
fit the flow pipe and then the dual
thermostat and bracket. Refer to
Section 5.4. Fit the thermostat phials
of the combined boiler/overheat
thermostat into the thermostat
pockets on the flow pipe. Refer to
Figure 5-4.
2. For 46/58 and 58/70 models – Fit the
thermostat phials of the combined
boiler/overheat thermostat into the
thermostat pocket in the top of the
boiler. Refer to Section 5.4. Push the
assembly fully home into the pocket,
and secure in position by tightening
the two fixing screws. Refer to Figure
5-2.
3. Undo the three screws securing the
combined boiler/overheat thermostat
cover and lift off the cover.
4. Withdraw the cable support bushes
from the cover. Pass the burner
supply cable through one of the
bushes and connect it to the boiler
(control) thermostat (refer to Figure
8-5) as follows:
Live (Brown) to terminal 1 on the
control thermostat
Green/Yellow to the earth terminal,
marked
, on the control
thermostat
5. Pass a switched mains power supply
through the other cable support
bush and connect it to the overheat
thermostat (refer to Figure 8-8) as
follows:
Switched live (Brown) to terminal C
on the overheat thermostat
Earth (Green/Yellow) to the earth
terminal (marked
) on the
overheat thermostat
One of the two Earth ‘flying leads’
(Green/Yellow) from casing to
earth terminal, marked
, on the
overheat thermostat
The remaining Earth ‘flying lead’
(Green/Yellow) from casing to earth
terminal (marked
) on the control
thermostat
Neutral (Blue) wire from incoming
switched mains supply must be
linked to the neutral (Blue) wire to the
burner using a single connector (not
supplied).
Refer to Figure 8-5 for typical system
wiring diagram.
For other systems not covered, contact
Grant Engineering (UK) Ltd.
dO NOT connect the neutral wires to
either of the two thermostats.
6. Connect a link between terminal 2 on
the overheat thermostat and terminal
C on the control thermostat.
7. There are NO connections
to terminal 1 on the overheat
thermostat and terminal 2 on the
control thermostat.
8. Position the support bushes so as
not to strain the connections when
the cover is replaced. Place the
cover in position locating the bushes
at the same time.
Electrical
It may be necessary to rotate the
thermostat knob to engage it on the
operating spindle as the cover is
replaced.
9. Secure the cover in position by
tightening the three screws. Tighten
the cable support bush nuts to
secure the cables.
10. Ensure that all external wiring is
adequately supported. Do not switch
on the electricity supply at this stage.
8.4 Frost Protection
For additional protection of either the
entire heating system, or the boiler and
localised pipework, it is recommended
that a frost thermostat be installed.
Refer to Figures 8-1 to 8-5 (as
appropriate) for connection details.
To protect the heating system, the
frost thermostat should be sited within
the house in such a place that it can
detect any rise and fall in the ambient
air temperature, i.e. in a room with a
radiator.
Where the frost thermostat is installed
outside the house (to protect a boiler
installed in an external boiler room or
garage) or in an attic, it is recommended
that it be used in conjunction with a pipe
thermostat to avoid unnecessary and
wasteful overheating of the property. The
pipe thermostat should be located on
the boiler return pipe, and set to operate
at 25°C.
Refer to Figures 8-1 to 8-5 (as
appropriate) for connection details.
WARNING
!
NOTE
!
