Programmers & Timers
Single Channel Programmer (time switch)
In short
A single channel programmer is a clock with one channel, also called a time switch. Inside is one changeover switch, fed from the live (L). Its terminals: E, L, N, 1, 2, 3, 4. Units based on makers’ products sit under it in the parts list, such as the Danfoss TS715Si and the Drayton LP711.
If this is your home: this page is written for heating engineers. Mains wiring and gas appliances are not DIY jobs; call a Gas Safe registered engineer. If you smell gas, leave the building and call the National Gas Emergency Service on 0800 111 999.
What it is
A SINGLE CHANNEL programmer is a clock with one channel, also called a TIME SWITCH. Inside is one CHANGEOVER switch, fed from the live (L). While it is ON, it puts a live on 2 and 4. While it is OFF, it puts the live on 1.
It times one service on its own: it is the programmer of a COMBI boiler, or of a system with one service to time. The thermostat times the heating, and the time switch the hot water.
The numbers are this simulator's own. A branded time switch prints its own, so read its plate. Many put the common on 1 and ON on 3 or 4. The ST9100C prints the words HW OFF and HW ON beside its L and N.
Terminals
| Terminal | What it is for |
|---|---|
| E (Earth) | The earth (E) PARKING SCREW. It holds the cable's earth core, in green-and-yellow sleeving. The unit itself does not use it. |
| L (Live) | The live (L) in. It feeds the clock and the switch. |
| N (Neutral) | The neutral (N) for the clock. |
| 1 | OFF: live while the channel is off. |
| 2 | ON: the DEMAND, live while the channel is on. |
| 3 | Not used. |
| 4 | ON: the same demand, on a second contact. 2 and 4 are not linked to each other inside. |
What the meter reads
With its live (L) and neutral (N) on, the clock runs. 2 and 4 are live while the channel is ON, and 1 while it is OFF. Without them, the switch rests on 1, OFF.
Press HEATING to turn the channel on or off. While the unit has its supply, the screen shows HEATING ON, with a flame, or OFF.
Units based on makers’ products
In the parts list these sit under the Single Channel. Each is the simulator’s own unit, simplified for teaching, and may differ from the product it is based on: on site, read the unit’s own instructions. DrawWarm is not part of these makers and is not approved by them.
- Based on the Danfoss TS715Si
- Based on the Drayton LP711
- Based on the Honeywell ST9100C
- Based on the Salus EP110
- Based on the Secure / Horstmann H17XL
- Based on the ESi ES1247B
- Based on the Honeywell ST6100Colder
Where it connects
Lessons that use it
- The single channel programmer
Foundation · The parts
- The installer's link
Intermediate · Reading branded units
- Hot water on its own timer
Intermediate · More zones
- Underfloor downstairs, radiators upstairs
Intermediate · Underfloor and mixed systems
- The UFH interlock
Intermediate · Underfloor and mixed systems
- Combi timer and room stat (page 48)
Worcester wiring
- Combi two heating zones (page 45)
Worcester wiring
Also in programmers & timers
Practise it in the simulator.
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