Here's a professional grade dual temperature digital contact thermometer that takes readings of T1, T2, or T1-T2.
Professional-grade contact temperature designed for professional, commercial or industrial HVAC and Service technicians. The temperature range -328°F to 2500 (-200°C to 1372) covers a wide range of applications. Dual temperature measurement provides faster measurement of heating and cooling systems for HVAC work. Relative time display function gives you easy tracking of minimum, maximum and average temperatures over time. Includes two (2) K-type thermocouples