Integrated system for heating water

Abstract

One variation of a water heater includes: a housing; a water tank arranged within the housing and configured to store water received from a cold water supply of a building; a heat pump arranged within the housing and configured to heat water stored in the water tank; an inline heater arranged within the housing and configured to heat water exiting the water tank; and a mixing valve arranged within the housing and configured to combine cold water from the cold water supply of the building with hot water exiting the water tank. The water heater is configured to: detect a water temperature of water stored in the water tank; and, in response to flow of water from the water tank, selectively activate the inline heater based on the water temperature to supply hot water, proximal the target supply temperature, to the building.

I claim: 
     
         1 . A water heater comprising:
 a housing;   a cold water inlet:
 arranged on the housing; and 
 fluidly coupled to a cold water supply of a building; 
   a water tank:
 arranged within the housing; and 
 configured to store water received from the cold water supply via the cold water inlet; 
   a heat pump:
 arranged within the housing; and 
 configured to heat water stored in the water tank; 
   an inline heater:
 arranged within the housing; and 
 configured to heat water exiting the water tank; 
   a hot water outlet:
 arranged on the housing; and 
 configured to fluidly couple the water tank to hot water supply lines within the building; 
   a mixing valve:
 arranged within the housing; and 
 configured to combine cold water from the cold water supply of the building with hot water between the water tank and the hot water outlet; and 
   wherein the water heater is configured to:
 at a first time:
 detect a first water temperature of water stored in the water tank; and 
 in response to flow of water from the water tank and in response to the first water temperature approximating a target supply temperature, supply hot water, proximal the target supply temperature, from the water tank to the building; 
 
 at a second time:
 detect a second water temperature of water stored in the water tank; and 
 in response to flow of water from the water tank and in response to the second water temperature falling below the target supply temperature, trigger the inline heater to heat water exiting the water tank toward the target supply temperature; and 
 
 at a third time:
 detect a third water temperature of water stored in the water tank; and 
 in response to flow of water from the water tank and in response to the third water temperature exceeding the target supply temperature, at the mixing valve, combine cold water with hot water, exiting the water tank proximal the third water temperature, to cool water exiting the water heater toward the target supply temperature. 
 
   
     
     
         2 . The water heater of  claim 1 , further comprising:
 a first power junction:
 configured to:
 couple to a first power supply limited to a first amperage; and 
 supply power to the heat pump; and 
 
 electrically isolated from the inline heater; and 
   a second power junction configured to:
 couple to a second power supply limited to a second amperage greater than the first amperage; and 
 supply power to the heat pump and the inline heater. 
   
     
     
         3 . The water heater of  claim 2 , further comprising a controller configured to:
 at an initial time preceding the first time:
 trigger the heat pump to heat water stored in the water tank when power is supplied to the first power junction; and 
   at the second time:
 in response to flow of water from the water tank and in response to the second water temperature falling below the target supply temperature when power is supplied to the second power junction:
 trigger the inline heater to heat water exiting the water tank; and 
 trigger the mixing valve to combine cold water with hot water, between the water tank and the hot water outlet, to cool water to the target supply temperature. 
 
   
     
     
         4 . The water heater of  claim 3 , wherein the water heater is configured to:
 during a fourth time period when power is supplied to the first power junction:
 heat water stored in the water tank via the heat pump; 
 detect a fourth water temperature of water stored in the water tank falling below the target supply temperature; and 
 supply water from the water tank, proximal the fourth water temperature, to the building. 
   
     
     
         5 . The water heater of  claim 1 , further comprising:
 a recirculation pump:
 arranged within the housing; and 
 configured to purge cooled water from hot water supply lines within the building with water stored in the water tank; and 
   a controller configured to:
 during an initial time period preceding the first time:
 access an initial water temperature in a first hot water supply line within the building; and 
 in response to the initial water temperature falling below the target supply temperature, activate the recirculation pump to pump water stored in the water tank, proximal the target supply temperature, to the first hot water supply line. 
 
   
     
     
         6 . The water heater of  claim 5 , wherein the controller is further configured to:
 access a water temperature in a hot water supply line within the building; and   in response to the water temperature approaching a freeze-risk temperature:
 trigger the recirculation pump to supply water, proximal the target supply temperature, to the hot water supply line. 
   
     
     
         7 . The water heater of  claim 1 , further comprising:
 an air inlet arranged on the housing and configured to supply inlet air to the heat pump;   a set of resistive heaters:
 arranged within the water tank; and 
 configured to heat water stored in the water tank; 
   an air temperature sensor configured to output signals representing air temperatures of air entering the air inlet; and   a controller configured to:
 during a fourth time period:
 access a first air temperature of air entering the air inlet based on a signal output by the air temperature sensor; and 
 in response to the first air temperature exceeding a minimum heat pump operating temperature:
 trigger the heat pump to heat water stored in the water tank toward the target supply temperature; and 
 
 
 during a fifth time period:
 access a second air temperature of air entering the air inlet based on the signal output by the air temperature sensor; and 
 in response to the second air temperature falling below the minimum heat pump operating temperature:
 trigger the set of resistive heaters to heat water stored in the water tank toward the target supply temperature. 
 
 
   
     
     
         8 . The water heater of  claim 1 , further comprising:
 an air outlet arranged on the housing and configured to exhaust air from the heat pump;   an air return valve configured to selectively couple the air outlet to:
 an external air source; and 
 an interior space of the building occupied by the water heater; 
   an air temperature sensor configured to output signals representing air temperatures proximal the water heater; and   a controller configured to:
 at the first time:
 access a first air temperature of the interior space of the building based on a first signal output by the air temperature sensor; and 
 in response to the first air temperature exceeding a threshold air temperature:
 trigger the air return valve to couple the air outlet to the interior space; and 
 
 
 at the second time:
 access a second air temperature of the interior space of the building based on a second signal output by the air temperature sensor; and 
 in response to the second air temperature falling below the threshold air temperature:
 trigger the air return valve to couple the air outlet to external air source. 
 
 
   
     
     
         9 . The water heater of  claim 1 , further comprising:
 an air inlet:
 arranged on the housing; and 
 configured to supply air to the heat pump; 
   an air supply valve configured to selectively couple the air inlet to:
 an external air source; and 
 an interior space of the building occupied by the water heater; 
   an air temperature sensor configured to output signals representing air temperatures proximal the water heater;   a set of resistive heaters:
 arranged within the water tank; and 
 configured to heat water stored in the water tank; and 
   a controller configured to:
 prior to the first time:
 access a first air temperature of air proximal the water heater based on a first signal output by the air temperature sensor; and 
 in response to the first air temperature exceeding a minimum heat pump operating temperature:
 trigger the air supply valve to couple the air inlet to the interior space of the building to supply air from the interior space of the building to the heat pump; and 
 trigger the heat pump to heat water stored in the water tank toward the target supply temperature; and 
 
 
 prior to the second time:
 access a second air temperature proximal the water heater based on a second signal output by the air temperature sensor; 
 access a third air temperature of the external air source; and 
 in response to the second air temperature and the third air temperature falling below the minimum heat pump operating temperature:
 deactivate the heat pump; and 
 trigger the set of resistive heaters to heat water stored in the water tank toward the target supply temperature. 
 
 
   
     
     
         10 . The water heater of  claim 1 , further comprising:
 an air inlet arranged on the housing and configured to supply inlet air to the heat pump;   a set of resistive heaters:
 arranged within the water tank; and 
 configured to heat water stored in the water tank; 
   an air temperature sensor configured to output signals representing air temperatures of air entering the air inlet; and   a controller configured to:
 during a first time period preceding the first time:
 access a first initial water temperature of water stored in the water tank; 
 access a first air temperature of air entering the air inlet based on a first signal output by the air temperature sensor; and 
 in response to the first initial water temperature falling below the target supply temperature by greater than a first threshold difference and in response to the first air temperature exceeding a minimum heat pump operating temperature:
 trigger the heat pump to heat water stored in the water tank toward the target supply temperature; and 
 
 
 during a second time period preceding the second time:
 access a second initial water temperature of water stored in the water tank; 
 access a second air temperature of air entering the air inlet based on a second signal output by the air temperature sensor; and 
 in response to the second initial water temperature falling below the target supply temperature by greater than a second threshold difference and in response to the second air temperature exceeding the minimum heat pump operating temperature:
 trigger the heat pump and the set of resistive heaters to heat water stored in the water tank toward the target supply temperature. 
 
 
   
     
     
         11 . The water heater of  claim 1 , further comprising:
 a shutoff valve:
 arranged within the housing; and 
 interposed between the cold water inlet and the water tank; 
   a pressure sensor:
 arranged downstream of the shutoff valve; and 
 configured to output signals representing water pressures in a hot water supply line within the building; and 
   a controller configured to:
 during a first time period:
 trigger the shutoff valve to transition from an opened position to a closed position to interrupt flow of water from the cold water supply to the water tank; 
 access a series of signals, output by the pressure sensor, representing water pressure in the hot water supply line while the shutoff valve occupies the closed position; 
 detect a water leak, within the building and downstream of the water heater, based on decay of water pressures represented in the series of signals; and 
 in response to interpreting the water leak, maintain the shutoff valve in the closed position. 
 
   
     
     
         12 . The water heater of  claim 1 , further comprising a condensate pump:
 arranged within the housing;   fluidly coupled to the heat pump; and   configured to pump condensate, generated by the heat pump while heating water stored in the water tank, to a head height greater than a height of the housing.   
     
     
         13 . The water heater of  claim 1 , wherein the water heater is configured to:
 at the first time:
 in response to flow of water from the water tank and in response to the first water temperature approximating the target supply temperature:
 deactivate the inline heater; and 
 at the mixing valve, interrupt mixing of cold water with hot water, exiting the water tank proximal the target supply temperature; and 
 
   at the third time:
 in response to flow of water from the water tank and in response to the third water temperature exceeding the target supply temperature:
 deactivate the inline heater. 
 
   
     
     
         14 . A water heater comprising:
 a housing;   a cold water inlet arranged on the housing;   a water tank:
 arranged within the housing; and 
 configured to store water received from a cold water supply of a building via the cold water inlet; 
   a heat pump:
 arranged within the housing; and 
 configured to heat water stored in the water tank; 
   a hot water outlet arranged on the housing;   a recirculation pump:
 arranged within the housing; and 
 configured to purge cooled water from hot water supply lines within the building with water stored in the water tank; and 
   wherein the water heater is configured to:
 at a first time:
 detect a first water temperature of water stored in the water tank; and 
 in response to flow of water from the water tank and in response to the first water temperature approximating a target supply temperature:
 supply hot water, proximal the target supply temperature and stored in the water tank, to the building; and 
 
 
 at a second time:
 in response to flow of water from the water tank:
 trigger the recirculation pump to draw cooled water from the building to the water tank; and 
 supply hot water, exiting the hot water outlet proximal the target supply temperature, to the building. 
 
 
   
     
     
         15 . The water heater of  claim 14 :
 further comprising:
 an inline heater:
 arranged within the housing; and 
 configured to heat water between the water tank and the hot water outlet; and 
 
 a mixing valve:
 arranged within the housing; and 
 configured to combine cold water from the cold water supply with hot water exiting the water tank; and 
 
   wherein the water heater is configured to:
 at a third time:
 detect a third water temperature of water stored in the water tank; and 
 in response to flow of water from the water tank and in response to the third water temperature exceeding the target supply temperature:
 at the mixing valve, combine cold water with hot water, exiting the water tank proximal the third water temperature, to cool water exiting the water heater toward the target supply temperature. 
 
 
   
     
     
         16 . The water heater of  claim 14 :
 further comprising:
 an air temperature sensor configured to output signals representing air temperatures proximal the water heater; and 
 a set of resistive heaters:
 arranged within the water tank; and 
 configured to heat water stored in the water tank; and 
 
   wherein the water heater is further configured to:
 during an initial time period preceding the first time:
 detect an air temperature proximal the water heater based on a signal output by the air temperature sensor; and 
 in response to the air temperature falling below a minimum heat pump operating temperature:
 trigger the set of resistive heaters to heat water stored in the water tank toward the target supply temperature. 
 
 
   
     
     
         17 . The water heater of  claim 14 , further comprising:
 an air outlet arranged on the housing and configured to exhaust air from the heat pump;   an air return valve configured to selectively couple the air outlet to:
 an external air source; and 
 an air supply duct of the building; and 
   a controller configured to:
 at the first time:
 access a first air temperature of an interior space of the building; and 
 in response to the first air temperature exceeding a threshold air temperature:
 trigger the air return valve to direct cooled air, generated by the heat pump and exiting the air outlet, toward the air supply duct of the building. 
 
 
   
     
     
         18 . The water heater of  claim 14 :
 further comprising a set of resistive heaters arranged within the water tank; and   wherein the water heater is further configured to:
 access a first initial water temperature of water stored in the water tank prior to the first time; and 
 in response to the first initial water temperature falling below the target supply temperature by greater than a threshold difference:
 trigger the heat pump and the set of resistive heaters to heat water stored in the water tank toward the target supply temperature. 
 
   
     
     
         19 . The water heater of  claim 14 :
 further comprising:
 an inline heater arranged within the housing and configured to heat water exiting the water tank; and 
   wherein the water heater is further configured to:
 at a third time:
 detect flow of water from the water tank proximal a third water temperature falling below the target supply temperature; and 
 trigger the inline heater to heat water exiting the water tank toward the target supply temperature. 
 
   
     
     
         20 . A water heater comprising:
 a housing;   a water tank:
 arranged within the housing; and 
 configured to store water received from a cold water supply of a building; 
   a heat pump:
 arranged within the housing; and 
 configured to heat water stored in the water tank; 
   a hot water outlet arranged on the housing;   an inline heater:
 arranged within the housing; and 
 configured to heat water exiting the water tank; and 
   wherein the water heater is configured to:
 at a first time:
 detect a first water temperature of water stored in the water tank; and 
 in response to flow of water from the water tank and in response to the first water temperature approximating a target supply temperature:
 supply hot water, proximal the target supply temperature and stored in the water tank, to the building; and 
 
 
 at a second time:
 detect a second water temperature of water stored in the water tank; and 
 in response to flow of water from the water tank and in response to the second water temperature falling below the target supply temperature:
 trigger the inline heater to heat water exiting the water tank toward the target supply temperature.