Horstmann 425 Tiara User Manual

The Horstmann 425 Tiara and Diadem programmers are 2 circuit central
heating and hot water programmers able to switch ON and OFF twice
every 24 hours. An advance switch is provided to make temporary
overrides to the ON or OFF periods and a selector switch gives a further
choice of programmes.
Horstmann 425 Tiara/Diadem
Electro-mechanical Programmers
User Operating Instructions
1

Horstmann 425 Tiara Specifications

General

Display	LCD
Battery Backup	Yes
Voltage	230V AC
Switching Current	3A
Temperature Range	5°C to 30°C
Weight	200g
Type	Electronic
Programming	5/2-day
Power Supply	230V
Contact Rating	3(1)A
Number of on/off times	3 per day
Boost Function	Yes

Summary

User Operating Instructions

The 425 Tiara/Diadem Programmer

Setting the Time and ON/OFF Times

Setting the Time of Day

Instructions on how to set the correct time of day on the programmer's dial.

Setting the ON/OFF Times

Guide to positioning tappets on the dial to define system ON and OFF periods.

Manual Overrides and Controls

Advance Control

Explanation of how to use the advance control for temporary overrides of ON/OFF periods.

Switch State Indicator

Details on the indicator showing the last operated tappet number.

Programme Options and System Types

Programme Override Facilities

Description of individual override options for Hot Water (HW) and Central Heating (CH).

Fully Pumped or Gravity Systems

Explanation of how programmes differ based on system type (fully pumped vs. gravity).

Indicators - Diadem Only

Notes on indicator illumination for the Diadem model.

Understanding Programmers and Service

What is a Programmer?

An explanation for householders on the function of programmers.

Service and Repair

Information regarding user serviceability and contacting support for faults.