Patent ID: 11867429
Assignee: RINNAI AMERICA CORPORATION
Field: Thermal processes and apparatus (Mechanical engineering)
Classification: CPC F | IPC F

Claim 6:
7. A hot water storage system comprising:
a storage tank including a tank inlet and a tank outlet;
a tank temperature sensor positioned adjacent to the tank outlet and configured to provide tank temperature information; and
a tankless water heater system comprising:
a heat exchanger including a heat exchanger inlet fluidically coupled to the tank outlet and a heat exchanger outlet fluidically coupled to the tank inlet;
a variable speed pump configured to provide an adjustable output flow rate of water through the heat exchanger;
an output temperature sensor disposed downstream of the heat exchanger outlet and configured to provide heat exchanger output temperature information; and
a controller configured to:
control an amount of heat added via the heat exchanger within a turndown ratio less than 13:1,
control the output flow rate of the variable speed pump based on the heat exchanger output temperature information,
turn off the variable speed pump when the tank temperature information is equal to or greater than a maximum temperature, and
control the amount of heat added and the variable speed pump to maintain the heat exchanger output temperature information within a threshold of a set point temperature, wherein the threshold is greater than or equal to five degrees Fahrenheit and the set point temperature is greater than or equal to 120 degrees Fahrenheit and less than or equal to 183 degrees Fahrenheit.