Today we will focus on Combustion and Ventilation makeup air. This vital, but often overlooked area is absolutely vital to the safe and efficient operation of fuel burning equipment such as the burners that provide the necessary heat for boilers. The combustion process, which is necessary for fuel fired boilers, requires oxygen to sustain the combustion process. The oxygen that is used in the combustion process, in most cases, is provided through the use of ambient air present in the machinery room. As the combustion process uses up the oxygen in the machinery room those oxygen levels must be replenished. OSHA 1910.134 states “Oxygen deficient atmosphere means an atmosphere with an oxygen content below 19.5% by volume”. If adequate makeup ventilation is not provided the oxygen levels in a fuel-fired boiler room can easily dip below this 19.5% threshold, therefore it is required to have a means of introduction to replenish this vital air for both employee safety and good clean combustion.
How makeup air is introduced into our boiler rooms is addressed in NBIC Part 1 1.6.6. While many methods may be used for the introduction of makeup and ventilation air, it should be understood that whichever method is chosen, it must provide the required volume of air to the room to support human life and combustion. Air MUST be provided to the boiler at the manufacturer’s specifications. If no specification is provided via the manufacturer then any applicable NFPA codes should be followed. Also, NBIC states that for permanent openings, i.e., louvers, a minimum unobstructed area of 1in2 per 2000 Btu/hr fuel input is required. A good rule of thumb is to maintain 10cfm/bhp of makeup air.
- 8cfm/bhp for combustion air
- 2cfm/bhp for ventilation air.
Makeup air openings SHOULD NEVER be blocked!!! It is a basic human instinct to want to cover cold drafty air openings in times of cold weather. This should never be allowed to happen as this can lead to many dangerous and inefficient situations. By not allowing boilers to properly breathe one can find themselves in an oxygen deficient environment. This can lead to boilers firing in a fuel rich state which can lead to serious health concerns for the employees of a facility as well as increased fuel cost. If oxygen is suddenly re-introduced to a boiler that was firing in a fuel-rich state this could also result in a highly dangerous furnace explosion. If the louvers for makeup air are power actuated, they SHALL be interlocked with the burner to ensure that the louvers are open during firing per NBIC Part 1 1.6.6.
Proper Ventilation is a requirement for employee safety as well as combustion efficiency. If the boiler is starving for air it will result in increased fuel usage, sooting and carbon monoxide production. All of these undesirable effects can be avoided by simply allowing the BOILER TO BREAHTE!!! In closing GCAP believes it to be good practice to constantly monitor oxygen levels in the boiler through the use of stationary detectors. For more information regarding Boiler Room air requirements keep up with our website or contact us here at GCAP. Stay safe out there!!!
