Commissioning a gas cooker and checking combustion

The commissioning sequence

For a conventional flueless cooker, complete the model’s prescribed checks, including the following.

1. Tightness test. Prove the connection is gas-tight before the cooker is used. Seeing it power up or light proves nothing about leaks.
2. Fuel and measurements. Confirm the appliance category, injectors and conversion settings suit the connected gas. Complete the operating-pressure and gas-rate measurements specified for the model, comparing each with its own target. A pressure reading does not measure heat input. Convert an LPG-set cooker correctly before natural-gas use; adjusting aeration alone is not a conversion.
3. Light each burner. Check ignition and whether the flame carries around each burner’s own ports, then judge the flame picture. Cross-lighting concerns one burner, not its separate neighbour. A correctly aerated natural-gas burner gives stable, crisp, mainly blue flames with well-defined inner cones, seated on the ports.
4. Turn each burner down. A flame that is stable at full rate can lift off or go out at simmer, so check the whole turn-down range.
5. Oven and grill. Compare the burner with the maker’s specified pattern; heat alone does not prove correct burning. Follow the required grill-door position, which can be safety-critical, and check the thermostat’s prescribed control action.
6. Prove each flame supervision device. Use the maker's flame-failure test for every burner fitted with that protection. On a manual-relight model, check that gas shuts off within its allowed response time. If automatic re-ignition is fitted, check the prescribed retry sequence and final shut-off if the flame is not restored. A steady flame shows neither.
7. Room and connection. Confirm the ventilation is present and unobstructed; even burning perfectly, a cooker releases carbon dioxide and water vapour into the room. Check the cooker is stable and the hose is not kinked or touching the hot flue outlet.
8. Handover. Confirm safe operation, explain safe use and ventilation, and leave the manufacturer's instructions. Warn that the cooker must never be used to heat the room.

What abnormal flames and faults tell you

• Lazy yellow flames with soot or blackened pan bases: investigate abnormal burning and possible CO. Do not treat persistent soot as running-in or try to cure it by increasing the gas setting.
• Yellow flames soon after cleaning: first check for a cap or crown refitted out of position, or ports blocked by residue. Food debris round the ports has the same effect.
• Flames lifting off the ports: a combustion fault to investigate.
• Roaring low down near the injector: light-back; the flame has burnt back to the injector.
• Delayed ignition: gas is reaching the burner before it lights. Check the ignition, the burner ports and seating, and the gas-air setup.
• One burner sparks but will not light: check its cap seating, clean dry ports and the ignition electrode.
• Part of one burner stays unlit or burns unevenly: check its ports, cap and crown. If the fault appears only at simmer, check the maker’s minimum-setting procedure. Correct the cause before handover.
• Oven flame dies after the control is released: first check that it was held for the maker’s specified lighting period. Repeated dropout after correct lighting points to the flame-proving system; investigate before use.

Compare observations with the complete model-specific checks. Flame colour alone does not measure CO: particles in the air can colour a flame, and expected tips vary with fuel and design. Persistent lazy burning or soot must be investigated before use. Poor combustion and inadequate ventilation can allow CO to accumulate; headaches during use call for the possible-CO response, not a diagnosis from appearance alone.

Working through a manufacturer's procedure

Where the pressure is measured

For the Rangemaster Excel 110 Dual Fuel, use a hotplate injector other than the wok injector. Another hotplate burner is lit for the reading, and the control serving the gauge connection is opened as prescribed. Compare the result with the appliance data badge; then turn off, remove the gauge and restore the burner correctly. Complete the soundness and operating checks before handover.

The Stoves 60 cm gas cooker guide identifies the oven injector as its pressure-test point. That is a different appliance procedure, not a reason to transfer an oven test point to the Excel 110. Working pressure and gas rate remain separate measurements.

When lighting does not succeed

On the Excel 110, the usual lighting hold is about 10 seconds. If the flame dies when the knob is released, return the control to off and leave one minute before the next attempt. That pause does not prove a fault has cleared: repeated failure after the correct lighting sequence needs investigation.

The Stoves 60 cm commissioning procedure allows a 15-second hold and expressly forbids a longer attempt. If ignition has not occurred, release the control and wait one minute before trying again. Do not respond to repeated failure by continually feeding gas and sparking.

Completing an LPG conversion

For the Excel 110 conversion from natural gas to LPG, fit the specified jets and turn each hotplate bypass adjustment clockwise until it reaches its stop. Apply the supplied LPG identification to the part of the data badge that previously described natural gas. Then complete the specified pressure, gas-soundness and burner-operation checks. A new label records the work; it does not perform or prove the conversion.

These settings belong to that model and direction of conversion. Do not transfer them to a different gas control or use an aeration adjustment as a substitute. The Stoves guide, for example, states that its burner aeration is fixed and cannot be adjusted. On the CDA HVG65 gas-on-glass hob, each injector's diameter is marked on its body in hundredths of a millimetre; match it to the conversion table rather than judging by eye.

Lids and igniters

On a Stoves cooker with a lid safety system, light every hotplate burner and close the lid: all the flames must go out. Tell the user the lid is never the way to turn the burners off; the knobs are always returned to off after use.

On the Excel 110, pressing any hotplate knob sparks every burner. Never take apart or clean around one burner while another is on, because of the risk of an electric shock.