How to Select the Correct Thermocouple
- 1). Figure out the high and low temperatures of your device. These should be in the manual, or written somewhere on the of the furnace or air conditioner. There are 8 types of thermocouples, 4 commonly used ones: K, J, E and T; and 4 that are used to measure extremely high temperature: C, S, R and GB. The chart in the resources section has the temperature scales.
- 2). Look at the junction connection on the current thermocouple. The area where the thermocouple wires reach the probe wall will be covered in a protective sheath. There are three types to choose from. Exposed thermocouples have a tip that is not covered by the sheath, while grounded thermocouples are connected directly to the inside probe wall, adding extra protection. Ungrounded thermocouples are not connected to the probe wall at all. Each of the 8 types of thermocouples are available in these three types.
- 3). Determine the material that covers the lead wire on the thermocouple. It will be made of either fiberglass, teflon, overbraid or flexhose. The fiberglass lead wire is enclosed with silicon resin, while the teflon one is insulated with teflon. The overbraid is made of stainless steel braiding, and the flexhose is stainless steel hosing. Use these clues to find a matching thermocouple to suit your device.