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This product is discontinued

Electro-mechanical Programmer

425 series mechanical programmers are the simplest way to control hot water and central heating in the home. A single circuit time-switch for straight forward, accurate time control. The 425 Coronet is particularly suitable for combi boiler systems, warm air systems and extra zone control.

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Model Replacement
425 Coronet (for loads of 3A or under)* The above units use the same backplate as H3747 and only require simple wiring changes H3747 or C1727**
* H3747 is not suitable for immersion heaters ** C1727 backplate change and rewire required (economical option)


  • Control of most domestic gas or oil-fired central heating and hot water systems
  • Combination (‘combi’) boiler systems
  • Stored hot water systems
  • Solid-fuel systems
  • Additional zone control


  • Simple to use with easily understood settings adjustable in seconds
  • All control elements are visually accessible
  • Allows the user to switch the heating Off or on early without disturbing any existing settings
  • Advanced controls to allow manual override On or Off
  • Allows the user to pre-set a choice of programmes
  • Coronet can be used for loads up to 3kw as well as conventional heating


  • Rotating 24-hour dial and tappet arrangement
  • Easy to install using a 9-pin backplate
  • Advance control to allow manual override On or Off
  • Programme options: On, Off, All day or Auto
  • 7 years no quibbles warranty

Technical specifications

Contact rating Single circuit 13 (6) A 230V AC
Contact type Micro-disconnection changeover voltage-free
Motor Synchronous 230V 50Hz double insulated
Power consumption 2.5W
Dirt protection Normal situations
Moisture protection Ordinary
Enclosure protection Ip20
Maximum operating +55°C
Temperature dial setting 2 On, 2 Off tappets, Min. On/Off period 45 mins
Dimensions 152 x 107 x 39mm
Mounting 9-pin wall fixing plate
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