Abstract: One example embodiment relates to a water heater controller. The water heater controller includes an operating conditions circuit structured to receive temperature measurement signals indicative of temperatures over time of water in a tank of a water heater, and occupancy measurement signals indicative of whether individuals are present in an area proximate the water heater. A drift threshold circuit is structured to, in response to the occupancy measurement signals indicating that an individual is present or not present, define a plurality of drift threshold levels to trigger operation of a heating element of the water heater. A control circuit is structured to controllably operate the heating element based on the occupancy measurement signals and on the plurality of drift threshold levels.

Abstract: One example embodiment relates to a water heater controller. The water heater controller includes an operating conditions circuit structured to receive temperature measurement signals indicative of temperatures over time of water in a tank of a water heater, and occupancy measurement signals indicative of whether individuals are present in an area proximate the water heater. A drift threshold circuit is structured to, in response to the occupancy measurement signals indicating that an individual is present or not present, define a plurality of drift threshold levels to trigger operation of a heating element of the water heater. A control circuit is structured to controllably operate the heating element based on the occupancy measurement signals and on the plurality of drift threshold levels.

Abstract: A method for estimating temperature drift and drive curves comprises the steps of: (1) obtaining a plurality of temperature data samples over a period of time, the period of time corresponding to one of a drive operation or a drift period of an environmental control unit; (2) if the period of time corresponds to a drive operation, calculating a plurality of drive curves, each curve calculated using a different data sample subset; (3) else if the period of time corresponds to a drift period, calculating a plurality of drift curves, each curve calculated using a different data sample subset; (4) determining which curve best fits the data samples; and (5) using the best fit curve to predict one of a future temperature at a known time or a future time at which a known temperature will be reached.

Abstract: A method for logging data from an HVAC system comprises the steps of: collecting, within a thermostat, a plurality of data elements corresponding to a current time, at least one user setting, at least one HVAC system state, and at least one environmental measurement; correlating, within the thermostat, the collected data elements according to the current time; and storing, within the thermostat, the collected data elements. The method may further comprise the steps of: transmitting the stored data elements from the thermostat to an external device; and analyzing, within the external device, the transmitted data to determine energy savings. The data may be transmitted from the thermostat when the thermostat receives a request from the external device. The data may be transmitted from the thermostat to the external device over a communication link comprising one of a hard-wired communication link or a radio frequency communication link.

Abstract: A method and apparatus for selecting an operating level of an HVAC system uses historic and predicted drive durations to ensure that drive periods fall within the recommended minimum and maximum drive times, thereby increasing efficiency and reducing strain on the system. The method comprises the steps of: receiving a minimum and a maximum drive time of the HVAC system; determining a current temperature of a room; estimating, based on a prior drive operation of the HVAC system, a time to drive the current temperature to a predefined desired temperature; and selecting an operating level of the HVAC system based on a relationship of the calculated drive time to the minimum drive time and the maximum drive time. Selecting the operating level comprises at least one of: selecting a fan speed; activating a compressor; activating an auxiliary or emergency heating element; or activating an auxiliary or emergency cooling element.