Q: What is the difference between the GPT-3 and SST-2?A: The GPT-3 has the capability of using two temperature sensors when controlling constant wattage cable so it can be used with both constant wattage and self regulating cable. ETI GPT-3 Freeze Protection Thermostat with GFEP, 120-277 VAC UL / CSA ETI SST-2 Automatic Freeze Protection Electric Thermostat. […]