External Electrical Controls - IDEAL icos system HE15 Installation And Servicing

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38 EXTERNAL ELECTRICAL CONTROLS

Wiring external to the boiler MUST be in accordance
with the current I.E.E. (BS.7671) Wiring Regulations and
any local regulations. For IE reference should be made
to the current ETCI rules for electrical installations.
The fuse rating should be 3A.
Room Thermostat
If the thermostat has a neutral connection, use it (it
provides for more energy efficient operation by reducing
switching temperature differentials).
Frost Protection
If parts of the pipework run outside the house or if the
boiler will be left off for more than a day or so then a
frost thermostat should be wired into the system. This is
usually done at the programmer, in which case the
programmer selector switches are set to OFF and all the
other controls MUST be left in the running position.
The frost thermostat should be sited in a cold place but
where it can sense heat from the system.
If the boiler is installed in a garage it may be necessary
to fit a pipe thermostat, preferably on the return
pipework.
Designation of the terminals will vary but the
programmer and thermostat manufacturers' leaflets will
give full details.
IMPORTANT.
Ensure that the frost thermostat is wired so that the
system pump and / or external flow control valve is
energised as appropriate.
Diagram A shows an application to boilers fitted with a
room thermostat only.
Diagrams B & C show applications to boilers fitted with
alternative time controls.
Earths are not shown for clarity but must never be
omitted.
32
INSTALLATION
A
L3 N L2 L1
Room 'stat
Mains in
System
controls
Optional
Frost 'stat
icos system -
Installation and Servicing
N
if required