Section 658-110-19 - Thermostatically-Controlled, Hand-Fired warm air Units1. A 250 degree Fahrenheit limit control shall be installed in the supply plenum not more than ten (10) inches above the top surface of the heat exchanger and shall extend at least twelve (12) inches into the supply plenum.2. The limit control shall automatically prevent operation of the furnace in the event of powerfailure or shut off when 250 degrees Fahrenheit temperature is reached whether or not the electrical power source is available.3. A barometric draft control, if required, shall be installed in accordance with the manufacturer's instructions.02-658 C.M.R. ch. 110, § 19