Air to water heat pump system having optimized operation

Abstract

An air to water heat pump system is configured to minimize operating cost of the system utilizing one or more of hot water demand patterns, present or predicted ambient conditions, and/or electrical power cost. The system may be configured to reduce production and/or storage of hot water during periods of low demand, and increase production and storage of hot or hotter water immediately prior to a period of predicted high demand for hot water. The system may be configured to take into account ambient weather conditions to increase production and storage of hot water during favorable ambient conditions, and/or to increase production and storage of hot water prior to predicted cold ambient conditions.

What is claimed is: 
     
         1 . A heat pump water heater system, comprising:
 an air-to-water heat pump unit including a compressor that compresses and heats refrigerant to heat water, and a heat exchanger that is configured to be exposed to ambient air from outside of a building whereby heat from the ambient air is transferred to refrigerant flowing through the heat exchanger;   a hot water tank system that is configured to receive and store hot water from the heat pump unit;   a plurality of temperature sensors that are configured to measure water temperatures in the hot water tank system, wherein the plurality of temperature sensors are configured such that a volume of water in the hot water tank system at a temperature above or below a sensed temperature can be determined based, at least in part, on measured temperatures from the plurality of temperature sensors, whereby a volume of hot water in the hot water tank system above a predefined temperature can be determined;   wherein the system is configured to supply hot water from the hot water tank system and/or the heat pump unit to a hot water system of a building having periods of reduced demand for hot water and periods of increased demand for hot water, wherein the periods of reduced and increased demand form predictable demand patterns;   and wherein the system is configured to produce hot water having a first temperature during periods of reduced demand for hot water, and prior to a predicted period of increased demand for hot water: 1) provide a load up cycle that includes reducing a temperature and/or a volume of hot water produced by the heat pump unit to initially increase a volume of water having a temperature that is less than the first temperature in the hot water tank system, followed by increasing a temperature and/or a volume of hot water produced by the heat pump to increase a volume of hot water in the hot water tank system having a temperature that is greater than the first temperature prior to the period of increased demand for hot water; and/or: 2) adjust a temperature and/or a volume of hot water produced by the heat pump united and stored in the hot water tank system above a preselected temperature based, at least in part, on present and/or predicted ambient temperatures whereby a volume of hot water in the hot water tank system is adjusted to increase efficiency by increasing production and storage of hot when the ambient temperature is sufficiently high to increase efficiency of the heat pump relative to the predicted efficiency during a period of increased demand.   
     
     
         2 . The heat pump water heater system of  claim 1 , wherein:
 the heat pump unit utilizes electrical power during operation;   the system is configured to adjust a temperature and/or a volume of hot water produced by the heat pump unit and/or stored in the hot water tank system to account for changes in cost of electrical power whereby the heat pump unit provides increased production and storage of hot water during periods in which a cost of electrical power is reduced, and the system provides at least some hot water to a building that was produced utilizing electrical power having a lower cost than the cost at the time the hot water is provided to the building.   
     
     
         3 . The heat pump water heater system of  claim 2 , wherein:
 the system is configured to utilize predicted hot water demand, outdoor temperature, and the cost of electrical power to minimize an estimated cost of electrical power.   
     
     
         4 . The heat pump water heater system of  claim 2 , wherein:
 the system is configured to be operably connected with a communication system to receive information concerning the cost of electrical power supplied to the system.   
     
     
         5 . The heat pump water heater system of  claim 4 , wherein:
 the hot water tank system includes at least two stratified tanks that are fluidly interconnected such that when the system is increasing a volume of hot water in the hot water tank system, hot water from the heat pump unit flows into a top of a first tank, water from a bottom of the first tank flows into a top of a second tank, water from a bottom of the second tank is returned to the heat pump unit and heated, whereby the temperature of the water in each of the tanks is higher at a top of the tank and lower at a bottom of the tank, and the water in the top of the first tank has a higher temperature than water in the top of the second tank.   
     
     
         6 . The heat pump water heater system of  claim 5 , wherein:
 a first water temperature sensor is located at an upper portion of the first water tank;   a second water temperature sensor is located at a lower portion of the first water tank;   a third water temperature sensor is located at an upper portion of the second water tank;   a fourth water temperature sensor is located at a lower portion of the second water tank;   a fifth water temperature sensor is located at an upper portion of the third water tank;   a sixth water temperature sensor is located at a lower portion of the third water tank;   and wherein the system is configured to determine a volume of hot water in the hot water tank system based, at least in part, on water temperatures measured by the first, second, third, fourth, fifth, and sixth water temperature sensors.   
     
     
         7 . The heat pump water heater system of  claim 1 , wherein:
 the system is configured to cause the heat pump unit to produce water at a first temperature during a baseline mode of operation;   the system is configured to cause the heat pump unit to produce water at a second temperature that is greater than the first temperature during a second mode of operation.   
     
     
         8 . The heat pump water heater system of  claim 7 , wherein:
 the system if configured to utilize the second mode of operation if the cost of utilizing the second mode of operation is less than the cost of utilizing the first mode of operation.   
     
     
         9 . The heat pump water heater system of  claim 8 , wherein:
 the system is configured to receive information concerning present and/or future electrical rates;   the system is configured to utilize the information concerning present and/or future electrical rates to determine if the cost of utilizing the second mode of operation is less than the cost of utilizing the first mode of operation.   
     
     
         10 . The heat pump water heater system of  claim 7 , wherein:
 the system is configured to utilize the second mode of operation if a present ambient temperature is greater than a predicted ambient temperature.   
     
     
         11 . The heat pump water heater system of  claim 8 , wherein:
 the system is configured to utilize the second mode of operation to increase a temperature of hot water stored in the hot water tank system to reduce a cost of operation even if the increase in temperature of hot water stored in the hot water tank system is not necessary to meet a predicted increase in demand for hot water.   
     
     
         12 . The heat pump water heater system of  claim 1 , wherein:
 the system is configured to provide a load up cycle based on user-identified demand patterns.   
     
     
         13 . The heat pump water heater system of  claim 1 , wherein:
 the system is configured to identify demand patterns and to provide a load up cycle based on the demand patterns identified by the system.   
     
     
         14 . The heat pump water heater system of  claim 1 , wherein:
 the system is configured to turn the heat pump unit ON and OFF based, at least in part, on temperatures from a pair of temperature sensors being below and above, respectively, LOW and HIGH temperatures;   the system is configured to utilize a first pair of temperature sensors during a baseline operating mode whereby the system maintains a baseline volume of stored hot water at a baseline temperature;   the system is configured to initially utilize a second pair of sensors during a load up cycle whereby the volume of stored hot water at the baseline temperature is initially reduced during a load up cycle;   the system is configured to utilize a third pair of sensors after the volume of stored hot water at the baseline temperature is reduced whereby a volume of hot water at or above the baseline temperature is increased prior to a predicted period of increased demand.   
     
     
         15 . The heat pump water heater system of  claim 14 , wherein:
 at least one of the ON and OFF temperatures of the third paid of sensors is greater than the baseline temperature whereby at least some stored hot water has a temperature that is greater than the baseline temperature.   
     
     
         16 . The heat pump water heater system of  claim 15 , wherein:
 the system is configured to cause the heat pump unit to produce hot water at a baseline output temperature in the baseline operating mode, and cause the heat pump unit to produce hot water at a load up output temperature that is greater than the baseline output temperature when the third pair of sensors is being utilized, whereby the system produces and stores at least some hot water having a temperature that is greater than the baseline temperature prior to a period of increased demand.   
     
     
         17 . A heat pump water heater system, comprising:
 an air-to-water heat pump unit that heats water utilizing a heat exchanger that is exposed to ambient air;   a hot water tank system that is configured to receive and store hot water produced by the heat pump unit;   wherein the system is configured to supply hot water from the hot water tank system and/or the heat pump unit to a hot water system of a building having periods of reduced demand for hot water and periods of increased demand for hot water, wherein the periods of reduced and increased demand form demand patterns that are at least somewhat predictable;   wherein the system is configured to: 1) utilize present and predicted ambient air temperatures to increase a volume and/or a temperature of water produced by the heat pump unit and/or stored in the hot water tank system when the ambient air temperatures provides more efficient production of hot water, and/or 2) utilize present and/or predicted electrical power costs to increase production and storage of hot water when electrical power costs are less than future electrical power costs.   
     
     
         18 . The heat pump water system of  claim 12 , wherein:
 the system is configured to utilize predicted periods of increased demand for hot water to provide a load up cycle prior to a period of increased demand, the load up cycle including initially reducing a volume and/or a temperature of hot water produced by the hot water tank system and stored in the hot water tank system prior to a period of increased demand, followed by increase a volume and/or a temperature of hot water produced by the hot water tank system and stored in the hot water tank system prior to a period of increased demand.   
     
     
         19 . The heat pump water heater system of  claim 18 , wherein:
 the system is configured to store a baseline volume of hot water at a baseline water temperature during a baseline operating mode, wherein the baseline operating mode is utilized after a period of increased demand and before a load up cycle;   the system is configured to adjust the baseline volume of hot water based, at least in part, on ambient air temperature, whereby a first volume of hot water is stored in the hot water tank system when the heat exchanger is exposed to a ambient air at a first temperature, and a second volume of hot water is stored in the hot water tank system when the heat exchanger is exposed to ambient air at a second temperature, and wherein the first volume of hot water is greater than the second volume of hot water, and the first temperature is less than the second temperature whereby a baseline volume of hot water stored in the hot water tank system is increased during cold ambient conditions and reduced during warm ambient conditions to thereby meet predicted demand.   
     
     
         20 . A method of controlling a heat pump water system having a heat pump unit including a heat exchanger that is exposed to ambient air and a hot water tank system that is configured to receive and store hot water produced by the heat pump unit, the method comprising:
 controlling a volume and/or a temperature of hot water produced and/or stored by the system to reduce a cost of supplying hot water to a building having a variable demand for hot water, wherein the control is based, at least in part, on one or more of: 1) predicted demand for hot water; 2) present and/or predicted ambient air temperature; and 3) the cost of present and/or future electrical power used to operate the heat pump unit.