CentaurPlus C21 & C27 Series 2
Installation Instructions
CentaurPlus C21 and C27 two channel programmers offer up to
three on/off periods a day for hot water and heating with a hot
water boost and heating advance facility.
Installation and connection should only be carried out by a
suitably qualified person and in accordance with the current
edition of the lET wiring regulations.
WARNING: Isolate mains supply before commencing
installation.
1
Fitting the backplate
Once the backplate has
been removed from the
pa ck agin g pl ea se
ensure the programmer
is resealed to prevent
damage from dust and
debris.
The backplate should
be fitted with the wiring
terminals located at the top and In a position that allows a total
clearance at last 50mm around the unit.
50mm
50mm
1 2 3 4
N L
50mm
100mm
Direct Wall mounting
Offer the backplate to the wall in the position where the
programmer is to be mounted, remembering that the backplate
fits to the left hand end of the control. Mark the fixing positions
through the slots on the backplate (fixing centres of 60.3mm), drill
and plug the wall, then secure the backplate position. The slots in
the backplate will compensate for any misalignments of the
fixing.
Wiring box mounting
The backplate may be fitted directly onto a single gang steel flush
wiring box complying with BS4662 using two M3.5 screws.
CentaurPlus controls are suitable for mounting on a flat surface
only, they must not be positioned on a surface mounted wall box
or on unearthed metal surfaces.
2
Electrical Connections
All necessary electrical connections should now be made. Flush
wiring can enter from the rear through the aperture in the
backplate. Surface wiring can only enter from beneath the
programmer and must be securely clamped. The mains supply
terminals are intended to be connected to the supply by means of
fixed wiring. Recommended cable sizes are 1.00 or 1.5 mm2.
CentaurPlus programmers are double insulated and do not
require an earth connection but an earth connection is provided
on the backplate for terminating cable earth connectors. Earth
continuity must be maintained and all bare earth connectors must
be sleeved. Ensure no earth conductors are left protruding
outside the central space enclosed by the backplate.
Internal wiring diagram - C21 & C27 Series 2
L
N
230V 50Hz
3
1 2
HW
CH
OFF OFF ON ON
4
CHHW
New Installations
Example circuit diagrams for some typical installations are
shown in the pages which follow. These diagrams are schematic
and should be used as a guide only.
Please ensure that all installations comply with current IET
regulations.
3
For reasons of space and clarity not every system has been
included and the diagrams have been simplified - for example
some Earth connections have been omitted.
Other control components shown in the diagrams, i.e valves,
Room stats etc are general representations only. However the
wiring detail can be applied to the corresponding models of most
manufacturers for example Honeywell, Danfoss Randall, ACL
Drayton etc.
Cylinder and Room Thermostat key;
C= Common; CALL = Call for heat or break on rise; SAT =
satisfied on rise; N = neutral.
L
N
E
MAINS
SUPPLY
N
L
L
N
BOILER
1.Gravity Hot water with pumped heating
1 2
3
N
PUMP
4
L
4
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