User's Manual

ManualsBrandsHorstmann ManualsThermostatsHorstmann 425 Tiara

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

Summary of content (6 pages)

PAGE 1
User Operating Instructions Horstmann 425 Tiara/Diadem Electro-mechanical Programmers 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.
PAGE 2
The 425 Tiara/Diadem Programmer The simple instructions contained in this user guide are designed to help with the programming and operation of these units.
PAGE 3
SETTING THE TIME OF DAY The dial rotates clockwise and makes one complete revolution every 24 hours. To set the correct time turn the dial clockwise by hand (using the levers on the clock face) until the correct time of day is against the line marked TIME. (See diagram opposite) SETTING THE ON/OFF TIMES The four setting tappets, coloured red and blue, are moved around the circumference of the dial to set your required ON and OFF times. These tappets work in pairs to switch the system ON and OFF.
PAGE 4
Manual Overrides ADVANCE CONTROL The advance control allows you to start an ON or OFF period early without altering the tappet, time or programme selection settings. Moving the advance control to the extreme right brings forward the operation of the next tappet. The switch state indicator then changes to the appropriate number. When the next tappet passes the time line, normal operation returns. When the programme selector is in the All Day position, tappets 2 and 3 do not operate.
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PROGRAMME OVERRIDE FACILITIES The hot water (HW) or central heating (CH) may be individually overridden as shown below: (options are limited on gravity systems) 24 Hrs - The system will be permanently ON All Day - The system will switch ON from tappet 1 (red) and OFF at tappet 4 (blue) Tappets 2 and 3 are ignored Twice - The system switches ON at tappet 1 (red), OFF at tappet 2 (blue), ON at tappet 3 (red) and OFF at tappet 4 (blue) Off - The timer continues to operate but the system will be
PAGE 6
What is a programmer? ... an explantion for householders. Programmers allow you to set ‘On’ and ‘Off’ time periods. Some models switch the central heating and domestic hot water on and off at the same time; while others allow the domestic hot water and heating to come on and go off at different times. Set the ‘On’ and ‘Off’ time periods to suit your own lifestyle.