CB / CBLE

Excess fuel use is almost always excess air in the combustion process or degraded heat transfer surfaces. Run a flue gas analysis to set the air-fuel ratio correctly, then check for scale and soot.

Most flame failure lockouts are a contaminated flame detector (UV cell or flame rod), a failed igniter, or a fuel supply problem. Clean the flame detector first. It fixes the fault in the majority of cases.

Low steam pressure with the boiler at full fire means heat transfer is degraded, most often from fireside soot or waterside scale. Compare flue gas exit temperature to baseline: a rise of more than 10 degrees C per 100 hours indicates fouling.

A lifting safety valve means the pressure controls failed to cut the burner at the operating setpoint. Inspect the operating pressure control and high-limit control for proper setpoint and contact operation. Do not attempt to adjust or prevent the safety valve from lifting.

Scale is calcium and magnesium carbonate or sulfate deposited from untreated or undertreated feedwater. It insulates tubes and causes overheating. Chemical descaling removes it; fixing the water treatment program prevents recurrence.

Identify whether the noise comes from the combustion side (burner, air blower, or flue gas ductwork) or the steam/water side. Combustion pulsation needs air-fuel ratio adjustment. Steam-side banging is water hammer.

Water hammer means condensate is pooling in the steam line and being picked up by high-velocity steam. Check that all drip legs are sized correctly, steam traps are discharging, and the system is warmed up slowly before opening the main steam valve.

Water level fluctuation (swell and shrink) is often caused by a faulty modulating feedwater valve, a high total dissolved solids level increasing foaming, or a worn feedwater pump. Check TDS and the level control valve response first.