In a Scotch marine boiler, the furnace is a large plain or corrugated tube running the length of the shell, and it takes the most radiant heat. In a watertube boiler it is the combustion space lined with water-cooled tube walls. Outside the trade, furnace usually means a forced-air heater, so a boiler technician hears furnace and boiler as two very different machines.
Furnace has a bulge right over the burner, somebody dry-fired this thing or it's scaled solid.
Call a boiler a furnace in front of a boiler tech and expect to be corrected.
Also heard as
- firebox
- furnace tube
Related terms
Scotch marine boiler
A horizontal packaged firetube boiler with a large internal furnace tube and two to four gas passes.
Bag
A local bulge in a boiler tube, furnace or shell plate where overheated metal has been pushed out by pressure.
Pass
One run of combustion gases from end to end through a boiler before they turn or leave.
Dry fire
To run the burner on a boiler that has lost its water, overheating and often destroying the heating surfaces.