Possible Clues:

• With the final change there's a certain amount of heat
• Gas-bill unit
• Gas bill measure
• The return of Mister with some heat
• A hot unit, the Marines!
• Unit of heat as in gas supply
• Unit of heat and gas measure
• One on the Bench gets heated
• Amount of heat used in the small room
• Article on marine's unit when the heat's on?