A pre-configured wiring centre for controlling heating zones.

Just connect power, boilers, thermostats and timers. SystemLex does the rest.



SystemLex is designed for up to:

  • Four zones
  • Two heat sources
  • Auxilliary functions (see below)
All connections are numbered for foolproof installation.

Let's look at the SystemLex board in more detail...


Wiring the zones...

Here is zone 1 on the left of the board.

Each heating zone is clearly marked. 

  • Terminal for clock
  • Terminal for thermostat (can be combined with the clock)
  • Terminal for zone pump (or motorised valve)
  • LED showing when that zone is supplying heat

There is also an LED to show that power is being delivered to the SystemLex.

All the LEDs are visible when the lid is in place.

This picture shows the mains fuse and also the fuse for the individual zone. 


Power supplies...

The power supplies are clearly marked


Boiler connections...

There are two sets of boiler supplies that switch in unison:

  • Permanent Live, Neutral, Earth terminations
  • Independent boiler voltage-free contacts to provide boiler switch-live or external controls link.

Auxiliary logic switching facility...

This set of connections may be used if an auxiliary function is to be performed, such as 'Hot Water Priority' or where an additional boiler, pump or valve is required.

There are two sets of 'voltage free' terminals situated at the right hand side of the wiring termination block. These switches have both normally open and normally closed sides. Both switches switch simultaneously when power is presented at any one of the auxilliary inputs.

The auxilliary inputs are independent of each other.

These terminals exist to cater for the unexpected control dilemmas that regularly occur during heating installation, and will easily solve many otherwise exasperating problems.


For more information on how to use SystemLex or any other Systemlink Product, see our Knowledge Zone


Technical downloads on SystemLex are here