Patent ID: 8511296

Claim:
A method of supplying heat to an end use from a solar hot water system, the system including a solar heating unit; a higher-temperature loop and a lower-temperature loop, the lower-temperature loop including a reservoir and an outlet line, and the higher-temperature loop including the solar heating unit; the reservoir having an exit to the outlet line which allows delivery of the liquid in the reservoir to an end use, and a pumping and control system comprising (i) a higher-temperature loop pump; (ii) a lower-temperature loop pump, (iii) a heat exchanger in fluid communication with both the higher-temperature loop and the lower-temperature loop; (iv) a temperature sensor in the solar heating unit; (v) a temperature sensor in the reservoir; and (vi) a controller designed to receive data from the temperature sensors and to transmit control information to the pumps, and which is physically integrated with the pumps and heat exchanger in a single unitary fixture, and configured to control the operation of the lower-temperature loop pump and higher-temperature loop pump based upon data supplied from the temperature sensors; the method comprising: (a) heating liquid in the higher-temperature loop with the solar heating unit; (b) delivering liquid from the higher-temperature loop to the heat exchanger, so that the liquid passes through a first side of the heat exchanger, (c) delivering liquid circulating in the lower-temperature loop to the heat exchanger so that the liquid passes through a second side of the heat exchanger, receiving heat from the liquid in the higher-temperature loop, (d) delivering a portion of the liquid from the lower-temperature loop that has been heated in the heat exchanger to an end use; (e) determining the temperature differential between the temperature of the liquid exiting the solar heating unit and the temperature of the liquid in the lower-temperature loop at the exit of the reservoir, and (g) controlling the flow of liquids through the higher-temperature and lower-temperature loops to the heat exchanger based on the temperature differential, to maintain a setpoint temperature in the reservoir, by: (i) calculating the actual temperature differential between the solar heating unit and the end use; (ii) turning both pumps on when the temperature differential is greater than ΔT s and running two pumps at a speed sufficient to transfer heat from the solar heating unit to the end use; (iii) turning off one or both pumps when the temperature in the reservoir exceeds a predetermined maximum.