I have a single-pole thermostat on a 240 v baseboard heater. The heater seems to be on continuously even when the thermo is turned completely down. Is it possible for a baseboard heater to operate on one leg of a 240 v circuit? And what do I need to do to get the heater to shut off beyond turning the breaker off on the circuit?

Either the stat is defective and is not opening when in the Off position, or there something is not wired correctly.