Secure Meters 425 TIARA, 425 DIADEM, 425 CORONET Installation Instructions

425 Series

Installation Instructions

The 425 range of traditional electro-mechanical
programmers offer a simple yet effective way of
controlling hot water and central heating with the twin
circuit Diadem and Tiara also allowing independent
control of both.

INSTALLATION AND CONNECTION SHOULD ONLY BE CARRIED OUT
BY A SUITABLY QUALIFIED PERSON AND IN ACCORDANCE WITH
THE CURRENT EDITION OF THE IET WIRING REGULATIONS.

WARNING: ISOLATE MAINS SUPPLY BEFORE COMMENCING
INSTALLATION

1

Fitting the backplate:

Once the backplate has been
removed from the packaging
please ensure the programmer is
re-sealed to prevent damage from
dust, debris etc.

The backplate should be fitted with the wiring terminals
located at the top and in a position which allows the
relevant clearances around the programmer
(see diagram)

Direct Wall Mounting

Offer the plate to the wall in the position where the
programmer is to be mounted, remembering that the
backplate fits to the right hand end of the programmer.
Mark the fixing positions through the slots,(fixing
centres 60.3mm), drill and plug the wall, then secure the
plate in position. The slots in the backplate will
compensate for any misalignment of the fixings.

Wiring Box Mounting

The backplate may also be fitted directly on to a single
gang steel flush wiring box complying with BS4662,
using two M3.5 screws. 425 electro mechanical
programmers 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. The
recommended cable sizes are 1.0mm or 1.5mm for a
Diadem / Tiara and 1.5mm for a Coronet.

2

2 2

425 Electro-Mechanical Programmers are double
insulated and do not require an earth connection but an
earth terminal is provided on the backplate for
terminating any cable earth conductors.

Earth continuity must be maintained and all bare earth
conductors must be sleeved. Ensure that no conductors
are left protruding outside the central space enclosed by
the backplate.

3

Diadem / Tiara:

When used to control MAINS
V OLT A G E S Y ST EM S
Terminals L, 2 and 5 should
be electrically linked by
means of a suitable piece of
sleeved conductor. When
used to control EXTRA LOW
VOLTAGE SYSTEMS these
links MUST NOT be fitted.

Coronet:

When used to control MAINS
V OLT A G E S Y ST EM S
Terminals L and 5 should be
electrically linked by means
of a suitable piece of sleeved
conductor. When used to
c on t ro l E XT RA LO W
VOLTAGE SYSTEMS these
links MUST NOT be fitted.

4

Interlocking - Diadem and Tiara only

If a Diadem or Tiara is used on gravity hot water/pumped
central heating systems the selector slides must be
interlocked for correct programme selection.

This is achieved by rotating the interlock located at the
top of the HW programme slide. First select 'Twice' on
the HW selector slide, then select the Off position on the
CH selector slide; this will reveal the screwdriver slot in
the interlock.

Position the screwdriver in the slot and rotate anti­clockwise until the slot is almost horizontal (a stop will
prevent the interlock from being turned too far).

Check for correct operation of programme slides. This
should result in the HW selector slide moving up to
match any CH selection (twice, all day and 24 hours).

When the CH slide switch is returned to any of the lower
positions (all day, twice and off), the HW slide switch will
stay in the uppermost position reached and will have to
be manually moved to the desired new position.

5

Typical wiring diagrams

Example circuit diagrams for some typical installations
on pages 7 & 8. These diagrams are schematic and
should be used as a guide only.

Please ensure that all installations comply with the
current lET regulations.

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 slats etc are general representations only.
However the wiring detail can be applied to the
corresponding models of most manufacturers.

6

Cylinder and Room Thermostat Key:
C = common CALL = call for heat or break on rise
SAT = Satisfied on rise N = Neutral

7

8

Fitting the programmer

If surface wiring has been used,
remove the knockout / insert from
the bottom of the programmer to
accommodate it.

Loosen the two 'captive' retaining
screws on the top of the unit. Now fit
the programmer to the backplate
and line the lugs on the programmer
with the flanges on the backplate.

End view of 425 electro
mechanical programmer

Swing the top of the programmer into position ensuring that the
connection blades on the back of the unit locate into the terminal
slots in the backplate.

Tighten the two 'captive' retaining screws to fix the unit securely,
then switch on the mains supply.

The tappets can now be set to suit the user's requirements.
Please refer to the user's guide provided.

9

GENERAL INFORMATION

Before handing over the installation to the user, always
ensure that the system responds correctly on all control
programmes and that other electrically operated
equipment and controls are correctly adjusted.

EXPLAIN HOW TO OPERATE THE CONTROLS AND
HA ND OV ER T HE U SE RS OP ER AT IN G
INSTRUCTIONS TO THE USER.

10

Specification: Coronet, Diadem and Tiara

Models:

Coronet: Single Circuit 13(6)A 230V AC
Diadem: Double Circuit 6(2.5)A 230V AC
Tiara: Double Circuit 6(2.5)A 230V AC
Contact type: Micro disconnection
(Voltage free, Coronet and
Tiara only)
Motor Supply: 230-240V AC 50Hz
Double Insulated:
Enclosure Protection: IP 20
Max. Operating Temperature: Coronet 35°C Diadem/Tiara 55°C
Dirt protection: Normal situations.
Mounting: 9 Pin Industry Standard Wallplate
Purpose of Control: Electronic Time Switch
Operating time limitation: Continuous
Type 1 Action
Case material: Thermoplastic, flame retardant
Dimensions: 153mmx112mm x 33mm
Clock: 24 hour
Programme selection: 24 Hours, On all day, Twice, Off
Operating periods per day: Two
Override: Instant advance
Backplate: 9 Pin terminal connection
Design Standard: BSEN60730-2-7

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NP0 02 76 73 00 0

Secure Meters (UK) Limited
South Bristol Business Park,
Roman Farm Road, Bristol BS4 1UP, UK
t: [phone] f: [phone]
e: [email protected]
www.Securemeters.com

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Part Number P27673 Issue 23