through-tube boiler

space

U+0020

hyphen-minus

U+002D

latin small letter b

U+0062

latin small letter e

U+0065

latin small letter g

U+0067

latin small letter h

U+0068

latin small letter i

U+0069

latin small letter l

U+006C

latin small letter o

U+006F

latin small letter r

U+0072

latin small letter t

U+0074

latin small letter u

U+0075