zero
one
two
four
locomotive boiler
Babcock and Wilcox boiler
Stirling boiler.
all of the above
Cochran boiler
Cornish boiler
1 tp 1.25m
1 to 1.75 m
2 to 4 m
1.75 to 2.75 m
supplied by same manufacturer loose and assembled at site
supplied mounted on a single base
purchased from several parties and packed together at site
packaged boiler does not exist