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(e)
Electrical Connection Testing
Carryout preliminary electrical checks below after wiring before switching on the supply: -
The insulation resistance to earth of mains cables.
Test the earth continuity and short circuit of cables.
Test the polarity of the mains.
5.2.01 Wiring – Conventional Systems
(a) The schematic wiring diagram of conventional heating system with vented or unvented domestic hot
water storage is shown in figure 5.3. Although diagram shows 2 zone valves, the boiler is equally
suitable for systems designed with a 3-port valve.
(b) When designing and planning the system wiring, take into account recommendations of control
manufacturers and requirements of controls selected.
(c) The boiler incorporates pump overrun control logic. Therefore only feed the system pump from the
boiler wiring terminals marked ‘L-P’, ‘N-P’, and ‘E’ (see diagrams 5.2 and 5.3) and not from a separate
electricity supply.
(d) The boiler has integrated frost protection control logic to prevent the boiler from freezing. This will be
automatically activated if the temperature inside the boiler drops below 5
o
C provided the electricity and
the gas supplies to the boiler are not switched off. If frost protection is required for other parts of the
heating circuit, then a 230Vac frost thermostat should be wired as shown in diagram 5.3.
VER: 02.3 _260505
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