Abstract: A mobile heating apparatus to heat a space for the treatment of bed bugs within the space includes an air mixing chamber, a fresh air inlet extending from outside the space to the mixing chamber; and a recirculation air inlet extending from inside the space to the mixing chamber. Air from the mixing chamber is passed through a heat exchanger and to an outlet for return to the space. A first CO sensor is associated with the fresh air inlet, and a second CO sensor associated with the recirculation inlet. A control, responsive to the first and second CO sensors, can disable the burner if the first CO sensor detects a CO level in the fresh air in excess of a first predetermined level, and disable the burner if the second CO sensor detects a CO level in excess of a second predetermined level that is higher than the first predetermined level.