Error D.83

Safety first:

- If you smell gas, turn off the gas supply at the meter, do not operate electrical switches or the boiler, get everyone out, and call the gas emergency number immediately.

- Turn the boiler off and isolate the mains electricity before doing any physical inspection. Do not remove the boiler casing or touch internal components unless you are a qualified engineer.

Initial checks a homeowner can do:

1. Check the boiler pressure gauge. Normal cold system pressure is typically around 1.0–1.5 bar. If pressure is below ~1.0 bar, the system may cause temperature-rise faults.

2. If pressure is low, repressurise using the filling loop: locate the flexible silver filling loop under the boiler (two small taps), open the taps together slowly while watching the pressure gauge until it reaches about 1.0–1.5 bar, then close both taps. Do not over-pressurise.

3. Bleed radiators to remove trapped air which can prevent circulation. After bleeding, check pressure again and repressurise if it has dropped.

4. Reset the boiler following the manufacturer’s instructions (normally press the reset button for a few seconds). Observe the boiler during restart to see if the error returns.

5. Check for visible signs of leaks around the boiler and pipework, and check the external condensate outlet for blockage or freezing in cold weather (a frozen condensate pipe can cause faults). Thaw a frozen condensate pipe with warm (not boiling) water runoff if safe to do so.

6. Visually check the flue terminal for obvious blockages (birds’ nests, debris). Don’t attempt to clear the flue from inside the boiler—leave that to an engineer.

If the fault persists or if you find any leaks, gas smells, or you are not comfortable performing the checks above:

- Call a Gas Safe registered engineer. Explain the D.83 / F83 fault and what you have already tried (pressure reading, bleeding, reset, any visible leaks or frozen condensate).

What an engineer will check and possible fixes (for information only):

- Test flow and return NTC thermistors and wiring for correct resistance and continuity; replace sensor or harness if faulty.

- Inspect and test the circulation pump and any isolation valves for correct operation; replace or service pump if required.

- Check for blockages, scale or failure in the heat exchanger; clean or replace as necessary.

- Test the gas valve and ignition components; correct adjustment or replace parts if faulty.

- Inspect the PCB and wiring for loose connections, moisture or faults and repair or replace as required.

- Pressure test the system for leaks and recommend a powerflush if there is debris affecting flow.

Do not attempt internal electrical or gas component repairs yourself. If the boiler locks out repeatedly after your basic checks, arrange a Gas Safe engineer visit so the fault can be diagnosed and repaired safely and legally.