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Central heating timers

A combination boiler only heats up water when you turn on a hot tap, so you don’t need to programme it.   However, if you have a hot water cylinder, the water in the cylinder will need to be heated up during the course of the day.

In most cases, the functions on your programmer are:

  • Auto or Twice means the heating goes on and off during the day at the times it has been programmed to do so
  • 24hrs or On means the heating stays on all the time
  • Off means the heating will remain off all the time
  • All day or Once means the heating will switch on at the first ‘on’ setting you have programmed and then remain on until the last ‘off’ setting of the day
  • Boost or +1hr switches the heating on for a one-hour boost of heat
  • Advance moves the programmer to the next ‘on’ or ‘off’ setting in the daily cycle


Programmer - Drayton LP111

This is a 24-hour time switch with 4 switching options, along with:

  • Boost and advance
  • Holiday mode
  • Automatic summer/winter time change
  • Built-in standard programme – 3 on/off settings
  • User instructions are available to download here

Programmer - Horstmann CentaurPlus C17

The Horstmann CentaurPlus C17 timeswitch will allow:

  • Up to 3 ON/OFF settings per day for each day of the week
  • Has a 1-hour manual boost
  • Advance button to temporarily override current settings
  • A programming switch allowing permanent selection of OFF/ON/AUTO/ALL DAY
  • User instructions are available to download here