425D Diadem Central Heating Programmer (Discontinued)

Please try Horstmann Programmers for alternative products.

425D Diadem Central Heating Programmer5015914551017425 Diadem

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Width: - 152mm
Height: - 107mm
Depth: - 39mm
Horstmann 425D Diadem Programmer
  • This twin circuit, hot water and central heating programmer, with indicator lights,
  • 16 programmes available for fully pumped systems, including independent programming of heating and hot water
  • and 10 programmes for gravity HW/pumped CH systems. Programmes allow permanently ON or OFF, On all day or ON/OFF twice a day.
  • An advance switch gives temporary override without altering settings.
  • The Diadem is ideal for gravity systems and fully pumped systems with spring return zone valves.


Horstmann Data & Wiring Sheet + Compatability list
Product Code
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product photo
HO 425D

425D Diadem Central Heating Programmer Clearance Stock