IDEAL Concord CXA 40/H Installation & Servicing Manual page 15

17 ZONES WITH BI-DIRECTIONAL MOTORISED VALVES
IMPORTANT
Terminal L2 may control the appropriate pump(s) directly,
provided that the total running or starting current does not
exceed 6A (resistive or inductive): if this rating would be
exceeded then appropriate switchgear must be used to
control the pumps indirectly.
Three zones are illustrated but the principles may be
extended as required, provided the above conditions are
met. Each relay will then require as many contacts as there
are zones.
Overrun
Since any zone may be the load during overrun, all zones
MUST individually be able to satisfy the conditions in the
foregoing paragraph. If not all zones can do this then
consider other means of control detailed on other sheets.
Concord CXA/H -
Installation and Servicing
INSTALLATION
Normal operation
When any thermostat is satisfied while others are calling for
heat, power is available via relay contacts to close the valve for
that zone. When all thermostats are satisfied (also when the
clock period ends) all relays will be off, so the zone valves
which were open will remain open for the pump overrun. At the
start of the next call for heat (or the next clock period) valves on
zones not calling for heat will motor shut.
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