I do not create heat or cold yet I control both I sense changes and respond without being seen I keep balance within a space and quietly adjust the environment what hidden controller keeps comfort in check

A glass envelope for ocean bound messages

I absorb what surrounds me without complaint I grow heavier as I do my task yet I can release everything with a simple squeeze I am soft but useful in cleaning and care what object takes in liquid only to give it back Alternative Answers:

A trail between two points High above valleys and water And could be left in suspension So, to pass the time, how about a game of cards?

I have legs but cannot walk, I have a seat but cannot talk. I'm often found where spirits flock.