Residential heat pump water heater

A method of heating water within a water storage tank of a heat pump water heater wherein a controller is operatively connected to a heat pump, heating elements and a first temperature sensor positioned near the top of the water storage tank, the method comprising:

• receiving temperature readings transmitted by the first sensor;
• processing the temperature readings transmitted by the first sensor in order to determine a drop in temperature of water near the top of the water storage tank below a threshold temperature;
• and
• selecting and energizing at least one of the heat pump and the electric heating elements in response to the drop in temperature of water near the top of the water storage tank below the threshold temperature;
• and
• prior to selecting and energizing the at least one of the heat pump and the electric heating elements, automatically determining, by the controller, whether the water level within the water storage tank is at a sufficient level to allow a heating sequence to begin by performing the following steps:
• initiating the condenser of the heat pump for a defined period of time,
• processing the temperature readings received from the sensor positioned to measure the temperature of the water storage tank in order to determine whether the temperature of the water storage tank has increased to a level that exceeds a defined increase level, and
• upon a determination that the temperature of the water storage tank has exceeded a defined level, disabling the heating sequence and transmitting a signal indicating that an insufficient level of water is within the water storage tank.

A heat pump water heater comprising:

• a water storage tank;
• a heat pump positioned wherein the heat pump condenser is positioned in contact with the side and bottom of the water storage tank, wherein the heat pump condenser includes a side portion wrapped around the exterior of the water storage tank side wall and a bottom portion arranged proximate to and in a heat exchange relationship with the bottom wall of the water storage tank, wherein the bottom portion includes the condenser inlet, whereby the refrigerant flows first through the bottom portion of the condenser before flowing through the side portion;
• a pair of electric resistance heaters, wherein a first electric resistance heater is positioned within the water storage tank in proximity to the bottom portion of the water storage tank, and a second electric resistance heater is positioned within the water storage tank in proximity to the top of the water storage tank;
• a temperature sensor positioned to determine the temperature of water within and in proximity to the top of the water storage tank;
• a controller configured to:
• process information representative of temperature readings measured by the temperature sensor to detect a change in the temperature of water in the water storage tank, wherein the controller is operative to automatically energize one or more of the heat pump, the first electric resistance heater, and the second electric resistance heater in response to the change of the temperature of water in the water storage tank, and
• prior to energizing one or more of the heat pump, the first electric resistance heater, and the second electric resistance heater, automatically determine whether the water level within the water storage tank is at a sufficient level to allow a heating sequence to begin by being configured to:
• initiate the condenser of the heat pump for a defined period of time,
• process the temperature readings received from the sensor positioned to measure the temperature of the water storage tank in order to determine whether the temperature of the water storage tank has increased to a level that exceeds a defined increase level,
• upon a determination that the temperature of the water storage tank has exceeded a defined level, disable the heating sequence, and
• transmit a signal indicating that an insufficient level of water is within the water storage tank.

A heat pump water heater comprising:

• a water storage tank;
• a heat pump, comprising a sealed system including a compressor an evaporator, a condenser and a refrigerant configured for refrigerant flow from compressor to condenser to evaporator and back to the compressor, wherein the condenser is positioned in a heat exchange relationship with the water storage tank for heating the contents of the tank;
• a first electric resistance heater positioned proximate the upper region of the water storage tank;
• a first temperature sensor positioned proximate the top of the water storage tank;
• and
• a controller operatively connected to the first temperature sensor and including an event flow module configured to receive and process data representative of temperature readings measured by the first temperature sensor in order to determine if water is flowing from the water storage tank, wherein the controller is operatively connected to the heat pump and the first electric resistance heater, the controller being further configured to automatically select and energize at least one of the heat pump and the first electric resistance heater in response to the temperature readings measured by the first temperature sensor,
• wherein the heat pump condenser is wrapped around the exterior of the water storage tank side wall, wherein the inlet of the condenser is positioned proximate the lower portion of the water storage tank side wall, whereby refrigerant flow through the condenser is initiated through the condenser proximate the lower portion of the water storage tank side wall,
• wherein the heat pump condenser includes a portion arranged proximate to and in a heat exchange relationship with the bottom wall of the water storage tank, wherein flow through the portion of the heat pump condenser that engages the bottom wall of the water storage tank occurs following flow through the portion of the condenser wrapped around the exterior of the water storage tank side wall.