A thermostat for use with multistage Heating, Ventilating and Air Conditioning (HVAC) plants where a proportional/integral control loop is present for each stage of the multistage HVAC plant. Filter constants, Ki and Kp as well as stage control points and interstage values can be set independently for...http://www.google.de/patents/US6101824?utm_source=gb-gplus-sharePatent US6101824 - Flexible thermostat controller that permits various control point profiles when controlling multistage HVAC equipment
