Integrated recirculation pump for non-condensing water heater
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Solution Overview
Problem
Traditional hot water storage tanks suffer from energy inefficiency due to heat loss, requiring continuous heating to maintain desired temperatures, and tankless water heaters face challenges in efficient recirculation and temperature control.
Innovation Solution
A hot water circulation system with a temperature sensor, water pump, and bypass circuit that recirculates hot water through a thermal bypass valve, allowing for efficient temperature regulation and reduced energy consumption by stopping the pump when the desired temperature is reached, and using a solenoid valve for controlled flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a storage tank is used to maintain water at desired temperature, then hot water supply is ensured, but energy efficiency deteriorates due to continuous heating requirements
Solution Approach 1:
The system uses periodic recirculation action where the pump operates intermittently rather than continuously. The controller activates the pump at scheduled intervals or when hot water is demanded, circulates water through the heat exchanger, and then stops it. This periodic operation eliminates continuous heating requirements while ensuring hot water availability when needed.
Solution Approach 2:
The system maintains continuous hot water readiness through recirculation without continuous heating. By circulating water through the heat exchanger periodically and using thermal energy storage in the circulating water, the system ensures continuous availability of hot water while avoiding continuous energy input for heating.
2Loss of energy
If tankless water heater with recirculation system is used, then energy efficiency is improved, but device complexity increases due to additional components
Solution Approach 1:
The heat exchanger serves multiple functions: it heats water during normal operation and also serves as a thermal storage medium during recirculation. The circulating water absorbs thermal energy from the heat exchanger and carries it to the storage tank, eliminating the need for separate heating elements in the recirculation loop.
Solution Approach 2:
The system uses the thermal energy already present in the heat exchanger and circulating hot water to heat the recirculation water, rather than requiring external heating energy. The hot water from the main line heats the recirculation water through heat exchange, making the system self-sufficient for recirculation heating.
3Reliability
If recirculation pump operates continuously to maintain hot water supply, then hot water availability is improved, but energy consumption increases
Solution Approach 1:
The pump operates periodically rather than continuously, activated by a controller based on timing schedules or hot water demand signals. The pump circulates water for predetermined intervals to charge the storage tank with hot water, then stops operation, significantly reducing energy consumption while maintaining hot water availability.
Solution Approach 2:
The controller monitors system conditions and activates the pump when hot water is needed or according to predetermined schedules. The system uses feedback from temperature sensors and demand signals to control pump operation, ensuring hot water availability while minimizing unnecessary pump running time and energy consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system enhances energy efficiency by preventing unnecessary heating and maintaining desired temperatures, reducing energy consumption and heat loss, while ensuring consistent hot water supply through controlled recirculation.
Implementation Method 1
a temperature sensor positioned proximate to the cold-water inlet of the water heater and configured to sense a temperature of water flowing in the cold-water inlet
Implementation Method 2
a water pump comprising a water pump inlet and a water pump outlet. The water pump outlet is fluidically coupled to the cold-water inlet of the water heater
Implementation Method 3
a thermal bypass valve fluidically connected to the hot water supply line and the cold-water supply port
Implementation Method 4
water has been heated by heating elements, either electrically or with gas burners
Implementation Method 5
a first pressure drop across the bypass circuit from the hot water supply line to the cold-water supply line is less than a second pressure drop from the hot water supply line to the thermal bypass valve
Data Source
AI summary
A hot water circulation system comprises a water heater having a cold-water inlet and a hot water outlet. A water pump circulates water through the water heater to produce hot water. The hot water is circulated to a thermal bypass valve, which is configured to close when hot water contacts a heat activated seal. A bypass circuit is coupled between the hot water outlet and the cold water inlet of the water heater. The bypass circuit prevents hot water from circulating from the hot water outlet to the cold-water inlet when the thermal bypass valve is open and promotes circulating hot water from the hot water outlet to the cold water inlet when the thermal bypass valve is closed. Upon a temperature sensor sensing hot water entering the cold-water inlet, the water heater turns of the water pump.