Programmers/Timers
Dual Channel Programmer
In short
Dual Channel Programmer: Controls HW and CH circuits. It has 7 terminals: E (Earth), L (Live), N (Neutral), 1 (HW OFF), 2 (CH OFF), 3 (HW ON), 4 (CH ON).
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.
Terminals
| Terminal | What it is | On an S-Plan | On a Y-Plan |
|---|---|---|---|
| E | Earth | Wiring centre terminal 3 (earth) | Wiring centre terminal 3 (earth) |
| L | Live | Wiring centre terminal 1 (permanent live) | Wiring centre terminal 1 (permanent live) |
| N | Neutral | Wiring centre terminal 2 (neutral) | Wiring centre terminal 2 (neutral) |
| 1 | HW OFF | — | Wiring centre terminal 7 (HW OFF, with the cylinder stat satisfied contact, on to the valve grey) |
| 2 | CH OFF | — | — |
| 3 | HW ON | Wiring centre terminal 6 (HW demand, on to the cylinder thermostat common) | Wiring centre terminal 6 (HW demand, on to the cylinder thermostat common) |
| 4 | CH ON | Wiring centre terminal 4 (CH demand, on to the room thermostat L) | Wiring centre terminal 4 (CH demand, on to the room thermostat L) |
How it fails
- Programmer: heating channel failed
The display says CH ON but terminal 4 never goes live: the heating relay inside the programmer has failed.
- Programmer: hot water channel failed
HW ON is selected but terminal 3 stays dead: failed hot water relay in the programmer.
Where it connects
Lessons that use it
- Permanent Live vs Switched Live
Electrical Fundamentals
- The Wiring Centre
Electrical Fundamentals
- The Programmer
Component Library
- Programmer Connections
S-Plan Wiring
- Programmer Connections
Y-Plan Wiring
- No Power to System
Fault Diagnosis
- Heating Not Working
Fault Diagnosis
- Hot Water Not Working
Fault Diagnosis
Systems it is part of
Also in programmers/timers
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