Common Steam Boiler Problems and What to Check

---

• Power Be sure the electricity is available at the boiler. If not, check the breaker, switch, or door switch. 
• Call for heatIs there a call for heat?
• Steam pressure Check gauge to see if the boiler is off on steam pressure.
• Fuel Hopefully your boiler installer used a gas pressure gauge on the gas piping. Look for closed valves on gas pipe. Usually a lack of gas trips the flame safeguard control. 
• Flame failure If the boiler is off due to the flame safeguard, press the reset button Once. If it trips the flame safeguard again, have the burner checked by an expert to determine the cause.
• Low water cutoff Look at the gauge glass on the boiler and see if there is a water level inside the tube. Press the manual reset on the auxiliary low water cutoff. 
• Gas pressure switch Press the button on the gas pressure switch if your boiler has one. The gas pressure switches should be located on the gas train and burner head. 
• Limit control Verify boiler steam pressure is lower than the steam pressure control setpoint. The boiler limit control is a manual reset control. Press the reset button on the control. 
• Door switch The door switch located just outside the boiler room could be pushed off.
• Adjustable orifice The adjustable orifice is used to slow the opening of the valve for smoother ignition. Sometimes they need to be opened a bit further by turning counter clockwise.
• Gas train vent The vent could be plugged stopping the gas valve regulator from opening. 

• Negative condition Boiler room could be in negative condition due to exhaust fans in building.
• Combustion air Insufficient combustion air for gas fired equipment.
• Blocked flue Check for flue blockage
• Blocked fireside of boiler Verify the fireside is not plugged with soot or debris.
• Electric shutoff valve upstream of regulator Check to see that an electric shutoff valve is not closing upstream of the gas pressure regulator
• Valve opening too fast Close adjustable bleed orifice in gas valve 

• Loose wire Disconnect power to burner and verify each wire terminal screw is snug. 
• Electrical voltage Verify the electrical voltage does not drop below 102 or above 132 VAC.
• Ambient temperature Verify boiler room temperature is below 140 Degrees F.
• Pilot solenoid Sticking pilot solenoid valve. 
• Enable relay is a Triac type relay A Triac type relay allows voltage leaks through before relay contacts fully make). Replace with “ice cube” or similar definite purpose relay. 
• VFD Drive is too close Install a power line “noise” filter at the supply side of the boiler’s power-on switch. 
• Draft proving switch Verify draft proving switch is working properly. Check for blockage in draft sensing tube. 
• Gas pressure Verify gas pressure does not drop below minimum gas pressure setting when other gas fired equipment operates. 
• Flame safeguard A failing flame safeguard control could cause the flame failures.
• Pilot flame A weak pilot flame can be pulled away from the flame sensor. 
• Excess draft Draft could pull the flame away from the  flame sensor. 

• Oil in the boiler If some pipes were threaded or replaced, the cutting oil from the threads might find its way to the boiler. Since it is lighter than water, it will float and disrupt the steam bubbles. This could cause surging and bouncing.
• Test the boiler TDS Elevated TDS or Total Dissolved Solids in the boiler water could allow foaming and carryover, which can cause wildly fluctuating water levels inside the boiler. 
• Control valve opening too quickly If the valve opens too quickly into the steam heater or kettle, the water can be pulled from the boiler and cause it to trip. 
• Chemical treatment The chemicals may have accidentally been overfed to the boiler causing bouncing.

• Low water cutoff The low water cutoff may require service or could be defective.
• System vacuum The system could be going into a vacuum and may need a vacuum breaker.  

• Scale Scale could be forming on the water side of the boiler. The water treatment specialist should be notified.
• Low Water The boiler water may be too low. If so, do not add water to the boiler until the boiler is shut off and cool.

• System leak A leaking nipple or pipe can allow the water to be lost and new water has to be introduced.
• Boiler leak A leak inside the boiler can allow the water to be lost and new water has to be introduced.
• Steam pressure too high If the steam pressure is too high, the water can be lost when the condensate flashes to steam and exit via the vent. 
• Leaking steam traps If a steam trap is leaking and allowing steam to enter the condensate side of the system, it could be lost through the tank vent.

• Flue gas leak If the hot flue gases are not going up the flue, they could cause discoloration of the boiler jacket.
• Exhaust fan An exhaust fan in the boiler room could pull the flue gases from the boiler and into the room.
• Insufficient combustion air If the combustion air opening is blocked or restricted, it could cause the flue gases to roll out of the boiler and into the boiler room.
• Plugged flue passages If the flue passages are plugged, the flue gases could spill from the boiler into the boiler room.

Discoloration of jacket could signify dangerous back drafting of flue gases and boiler should not operate until checked.