If the temperature of the air passing through the radiator rises, the heat alerts a bimetal coil spring to "uncoil" or expand.
(the air; passing; through the radiator) (the temperature of the air; rises; ) (the heat; alerts; a bimetal coil spring to "uncoil" or expand)
the air the temperature of the air the heat
passing rises alerts
through the radiator
a bimetal coil spring to "uncoil" or expand