return-flue boiler

18 LETTERS · STARTS WITH R

return-flue boiler is a valid 18-letter word worth 21 points in Scrabble and 27 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS

R1E1T1U1R1N1-0F4L1U1E1B3O1I1L1E1R1

1 + 1 + 1 + 1 + 1 + 1 + 0 + 4 + 1 + 1 + 1 + 0 + 3 + 1 + 1 + 1 + 1 + 1 =21 PTS

DOUBLE WORD → 42TRIPLE WORD → 63

MEANING

What does return-flue boiler mean?