Section 8: Electrical Page 27
BURNER LEAD PLUG/SOCKET CONNECTOR
On all models, the electrical cable between the boiler control
panel and burner is now tted with an in-line 3-way plug
and socket connector. This enables the burner to be easily
disconnected from the boiler control panel for ease of removal
and servicing.
! NOTE !
A Service switch is tted to the control panel to allow the
Service Engineer to test-re the boiler.
When set to ‘ON’ the switch temporarily by-passes the
external control system to operate the boiler.
This is a ‘momentary’ or non-latching switch that cannot be left
set to ON. The boiler will automatically revert to normal operation
when 15 minutes have elapsed since it was last operated.
If required, this 15 minute override period can be stopped by
switching the boiler On / O switch OFF and then back to ON.
The boiler will then operate as normal under control of the
external heating/hot water controls (timer, room thermostat or
programmer).
8.3 FROST PROTECTION
The boiler is tted with a pre-set internal frost protection
thermostat. If the air temperature around the boiler falls below
2°C, then this thermostat will be activated to protect the boiler
from freezing.
Also, to protect any exposed heating system pipework, it is
recommended that an ‘external’ frost thermostat is also installed.
This frost thermostat will operate in parallel with the internal frost
protection of the boiler.
It 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.
For connection details please refer to Figures 8-1 and 8-2.
! NOTE !
For total system protection against freezing, particularly
during extended periods without electrical power, Grant
recommend the use of a combined heating system
antifreeze and corrosion inhibitor, used in accordance with
the manufacturer’s instructions.
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