Horstmann 425 range User Manual

1
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 IEE WIRING REGULATIONS.
WARNING : ISOLATE MAINS SUPPLY BEFORE COMMENCING INSTALLATION
Horstmann 425 range
Installation Instructions

Horstmann 425 range Specifications

General

Brand	Horstmann
Model	425 range
Category	Switch
Language	English

Summary

Fitting the Backplate

Direct Wall Mounting

Instructions for mounting the backplate directly to a wall, ensuring correct clearances.

Wiring Box Mounting

Instructions for mounting the backplate to a single gang steel flush wiring box.

Electrical Connections

Guidance on making electrical connections, cable sizing, and maintaining earth continuity.

Diadem/Tiara Wiring

Diadem/Tiara Mains Voltage Systems

Wiring instructions for Diadem/Tiara with MAINS VOLTAGE SYSTEMS, linking terminals L, 2, and 5.

Coronet Wiring

Coronet Mains Voltage Systems

Wiring instructions for Coronet with MAINS VOLTAGE SYSTEMS, linking terminals L and 5.

Interlocking Diadem and Tiara

Selector Slide Interlocking

Procedure for interlocking selector slides on Diadem/Tiara for correct programme selection.

Typical Wiring Diagrams Overview

Combination Boiler Diagram

Example circuit for a 425 Coronet controlling a combination boiler via room thermostat.

Gravity Hot Water Diagrams

Wiring examples for gravity hot water systems with pumped heating via room/cylinder stats.

Fully Pumped System Diagrams

Wiring examples for fully pumped systems with various valve configurations.

Fitting the Programmer Unit

Securing the Programmer

Steps for attaching the programmer unit to the backplate and switching on mains supply.

User Requirement Settings

Instructions for setting the tappets to suit user requirements, referring to the user's guide.

General Installation Information

System Response Check

Ensure system responds correctly and other equipment is adjusted before handover.

User Handover

Explain controls and hand over user operating instructions to the user.

Product Specifications

Model Specifications

Details on Coronet, Diadem, and Tiara models including circuits, voltage, and contact type.

Operating Characteristics

Information on motor supply, enclosure protection, temperature, and control purpose.

Physical and Functional Details

Case material, dimensions, clock type, program selection, override, and backplate connection.