How to find the air flow required for a forced draft fan?

Question

If a boiler uses forced draft fan for supplying air to boiler, How to find the mass of air required?

Answer 1

you are going to have two requirements, combustion air and ventilation air.  The ventilation air is the air required to maintain whatever your indoor design temperature using CFM = heat gain/(1.08*deltaT).

The combustion air requirements can be found in the International Mechanical Code section 706.  It is 1 CFM per 2400 BtuH of combined input rating of all combustion equipment in the room.

add those two up and you have the amount of ventilation you need.

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