Honeywell I mm ersion Well, 1/2" NPT, 3/8" Bulb Dia., 3" Max. Insertion/Bulb Length

HVAC thermowells protect temperature sensors from flow, high pressure, and harsh environments. Thermowells allow sensors to accurately measure liquid temperatures without substantially insulating the sensors. Also known as immersion wells, aquastat wells, and bulb wells, they consist of a tube that's closed at one end and mounted in the stream. The temperature sensor inserts into the open end of the tube, which is typically in the open air outside the pipe or vessel.