Image is for illustration only and should not be relied upon Horstmann (Secure) Diadem Programmer

Horstmann (Secure) Diadem Programmer

Ex Tax: £59.99
HCO Code: 03A02
Availability:  Out Of Stock

H425 Diadem

This twin circuit hot water and central heating programmer with indicator lights has 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. A new backplate is included with the 425 Diadem.


Compatible alternatives with same backplate & wiring:
Horstmann H21XL - 24 Hour digital programmer with boost holiday & 5 year warranty
Horstmann H27XL - 7 day digital programmer with boost holiday & 5 year warranty

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Will this programmer work with a Potterton combi HE plus boiler
With a combi boiler you would usually use the Coronet model as hot water is not needed.
Is there a room thermostat to go with this unit
Any room thermostat can be used with this programmer.
Hi, Would the Horstmann Diadem Programmer be a suitable replacement for my Smiths, Switchmaster 600? (one of it's buttons has stuck!) Please advise. Best Regards..
Yes it would.
Can this programmer be replaced with an electronic programmer?
Yes, HCO Code 01D02 will clip onto the existing backplate for a simple swap.

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