Yes, CHIMNEYS is a Scrabble word!

Letter values in Scrabble US: C 3, H 4, I 1, M 3, N 1, E 1, Y 4, S 1.

Is it a valid word?

CHIMNEYS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a vertical flue that provides a path through which smoke from a fire is carried away through the wall or roof of a building
a glass flue surrounding the wick of an oil lamp

Also: lamp chimney.