Boiler
CSI Division 23, HVAC
A pressure vessel that heats water or generates steam by burning fuel or using electric resistance, used to provide space heating, domestic hot water, or process heat throughout a building, sized and selected, fire-tube or water-tube, condensing or non-condensing, based on the building's actual heating load and fuel availability.
Why it matters
A boiler is a pressure vessel operating at genuinely dangerous temperatures and pressures, so its installation, venting, and combustion air supply are governed by specific code requirements, and a mistake in any of those isn't just an efficiency problem, it's a real safety hazard.
On a real project
A building's mechanical engineer specifies a condensing boiler sized to the calculated heating load, with venting and combustion air sized specifically to the manufacturer's requirements for that unit rather than a generic vent size assumed to work for any boiler.
Who this matters most to
A Pipefitter or HVAC Technician installs the boiler and its piping. A MEP Engineer calculates the building's heating load and selects the boiler sized to meet it.
Where this goes wrong
A contractor installs a boiler using a smaller vent size than the manufacturer's installation instructions specify, assuming any reasonably sized vent will work. The undersized vent causes incomplete combustion and a buildup of carbon monoxide, caught only when a combustion safety inspection during commissioning flags the mismatch before the building is occupied.