Error D.23

Safety precautions:

- Do not open the boiler casing or work on gas plumbing or internal wiring unless you are a qualified, Gas Safe registered engineer. Isolate mains electric and gas only if instructed by a Gas Safe engineer.

- Only use the boiler display and menus to read/change settings. Avoid changing other d.### settings unless you know their function.

- If you smell gas or suspect a leak, ventilate the area, do not operate electrical switches or the boiler, and call the gas emergency number immediately.

Initial checks a homeowner can do:

1. Check the room thermostat and programmer: ensure the programmer/room thermostat is calling for heat (set to a temperature higher than room temp and set the heating schedule to ON). If the thermostat is not calling, the boiler will not fire regardless of D.23.

2. Verify domestic hot water: turn on a hot tap. If hot water is available but radiators are cold, the behaviour is consistent with a summer-mode heating disable.

3. Check boiler pressure on the gauge: ensure system pressure is within normal range (typically around 1.0–1.5 bar cold). Low pressure can prevent heating.

4. Note any F‑codes or warnings on the display. Genuine fault codes (F.xx) indicate a problem that needs engineer attention and are separate from D.23.

How to check/change D.23 (model-dependent; proceed only if comfortable and you understand installer menus):

1. Wake the display by pressing any button. Accessing diagnostic menus varies by display version. On many ecoTEC Plus displays you enter diagnostic mode by pressing the "i" (information) button and the "+" button together. If this does not work for your panel, consult the user manual or stop and call an installer.

2. Once in diagnostics, scroll to d.23. The display will show the current value: 1 = heating enabled (winter), 0 = heating disabled (summer).

3. If d.23 shows 0 and you want to enable heating, change the value to 1. Be aware some models require installer access level or a code to alter settings; if the menu is locked do not force changes.

4. After changing, exit diagnostics and request heat (raise the thermostat temperature or set central heating to ON). Observe whether the boiler fires and the pump runs. Listen for the burner and check radiators after a few minutes.

If D.23 is already set to 1 but the heating still does not work:

- Check for displayed F‑codes and record them. F‑codes indicate component or safety issues (sensors, pump, fan, gas valve) and require a Gas Safe engineer.

- Confirm system water pressure and bleed radiators if air is suspected.

- If you changed D.23 and the boiler behavior changed but you then see alarmed F‑codes, revert the setting if possible and call an engineer.

When to call a professional:

- If you cannot access or safely change the diagnostic setting, or if the menu is locked at installer level.

- If changing D.23 does not restore heating, or any F‑codes appear after making changes.

- If you detect gas smell, water leaks, persistent low pressure or error codes indicating sensor or safety trips.

A qualified Gas Safe engineer should be called to diagnose and repair wiring, sensors, pump or gas components and to make any installer-level configuration changes if needed.