The single-stage A1101 thermostat can be used with most 24volt,1stage heat and/or 1 stage cool: gas, oil, or electric heating General The single-stage A1101 thermostat can be used with most 24volt,1stage heat and/or 1 stage cool: gas, oil, or electric heating and air conditioning systems, or single-stage heat pumps. The multi-stage A1102 thermostat can be used with most 24volt, 2 stage heat and/ ...