Why coals, radiants and fuel beds must match the maker's layout exactly, and how to judge the flame picture that results.
Why the layout is a safety matter
The coals, radiants or ceramic fuel bed are part of how the fire burns. The manufacturer sets the type, number and position of every piece to achieve correct air and gas mixing and complete combustion.
If pieces are rearranged, missing, broken or added, the flames can strike them or burn starved of air. The result is sooting and incomplete combustion, which can produce carbon monoxide: colourless, odourless and tasteless. A customer piling the coals into a thick heap, or a careless refit after cleaning, is a classic cause.
Radiants
On a radiant fire the ceramic radiants sit in front of the burner and glow when heated, radiating heat directly to people and surfaces. That is how a radiant fire delivers most of its warmth. Their position also shapes the flames, so broken or wrongly placed radiants disturb combustion.
Judging the flame picture
Compare the flames with the picture the manufacturer specifies for that model:
- Use the specified flame shape and colour for the actual burner. A radiant or convector label does not tell you how the flames should look.
- Some fuel-effect burners deliberately produce yellow flames, including models that provide radiant and convected heat.
- Sooting, staining or a persistent departure from the specified pattern needs investigation. A normal-looking flame does not measure CO or replace the required combustion and flue checks.
On a service
- Check the type, number and position of the pieces against the layout diagram.
- Replace damaged pieces only with the specified parts, including the fret. Substitute parts disturb the flame picture and combustion.
- Confirm the flame picture matches the specification once the fuel bed is in place.