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INSTALLATION
19
Concord CXSi/H - Installation & Servicing
16
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.
Normal operation
When any thermostat is satisfied while
others are calling for heat, power is
At the start of the next call for heat (or the next clock period)
valves on zones not calling for heat will motor shut.
Water circulation system - refer to page 5
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 period.
17
ZONES WITH INDIVIDUALLY PUMPED ZONES (3 zones shown)
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. For each zone (except Zone
1) a relay with 2 C/O contacts is required.
Overrun
During overrun periods, Zone 1 pump performs
the overrun facility; this zone, therefore, must
satisfy the conditions in the foregoing paragraphs
and Graph 1.
Normal operation
During a call for heat on Zone 1 only, Zone 1
thermostat energises the boiler, which in turn
energises Zone 1 pump from terminal L2.
During a call for heat on other zones the
appropriate relay directs power to L1 to energise
the boiler, at the same time ensuring that Zone 1
pump is controlled by Zone 1 thermostat.
Water circulation system - refer to page 5
INSTALLATION
157294-3.pmd 11/8/2005, 9:59 AM19