Gas sample monitoring apparatus

Apparatus 30 for use in a sample monitoring system includes a first enclosure 40 configured to enclose a probe body 80 into which the sample is drawn, a sensor 90 coupled to the probe body to sense a chemical composition of the sample and at least one first heater 100 to heat an interior of the first enclosure, a second enclosure 50 to enclose a pump 110 coupled to the probe body and configured to draw the sample therein and a second heater 120 to heat the pump, and a third enclosure 60 configured to enclose a pump motor 130 to control operation of the pump and to support heating control units 140, 141 to control the at least first and second heaters 120. The sensor may monitor oxygen on a hot wet basis in exhaust gases in a power plant.