Commercial Hot Water Recirculation With Timed Pump Control
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Solution Overview
Problem
Commercial plumbing systems with continuous hot water recirculation waste energy due to high heat loss and inefficient operation, particularly at night when hot water demand is low, leading to prolonged wait times for hot water at fixtures.
Innovation Solution
A hot water delivery system with a controller that uses a temperature sensor and timer to manage the operation of a pump, ensuring continuous or sporadic recirculation based on demand, preventing unnecessary heat circulation and optimizing energy use by turning the pump on only when needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous recirculation is used, then hot water availability is improved, but energy consumption increases
Solution Approach 1:
The system uses periodic action by implementing both continuous recirculation during daytime hours (when hot water demand is high) and shutdown during nighttime hours (when demand is low). The controller automatically switches between these modes based on time of day, ensuring hot water availability when needed while minimizing energy consumption during low-demand periods.
2Loss of energy
If recirculation pump is turned off at night, then energy consumption is reduced, but hot water availability deteriorates
Solution Approach 1:
The system applies preliminary action by maintaining continuous recirculation during daytime hours before nighttime demand occurs. This ensures that hot water is already available in the distribution system during periods of high demand, and the pump is only shut off during nighttime when demand is minimal, thus preparing the system in advance to meet user needs.
3Ease of operation
If recirculation operates during day, then hot water demand is met, but water waste occurs
Solution Approach 1:
The system implements periodic action by operating the recirculation pump continuously during daytime hours when hot water demand is high, ensuring immediate hot water availability at fixtures. The pump is automatically shut off during nighttime hours when demand is low, thereby minimizing water waste while maintaining ease of operation during peak usage periods.
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
This solution reduces energy waste by ensuring hot water is available quickly while minimizing heat loss and energy consumption, particularly during periods of low demand, thereby enhancing the efficiency of the recirculation system.
Implementation Method 1
A temperature sensor, connected to the control system, is provided for causing the controller to stop the pump to prevent heated water from being circulated
Implementation Method 2
A pump is provided which is interconnected between the boiler and the storage tank, for circulation of the water from the storage tank to the fixture and return to the storage tank
Implementation Method 3
a timer connected to the controller is provided for causing the controller to turn on the pump
Implementation Method 4
Alternatively, a flow detector may be installed in the hot water delivery line and connected to the controller for automatically causing the controller to turn on the pump
Data Source
AI summary
A commercial hot water system includes a boiler, a storage tank, and a hot water delivery line connected between the storage tank and at least one plumbing fixture along with a cold water delivery line connection between said plumbing fixture, a cold water source and said boiler. A pump, interconnected between the hot and cold water delivery lines, enables circulation of water to the fixtures. A timer and controller provides for turning on the pump and a temperature sensor, connected to the controller, is effective in stopping the pump to prevent heated water from being circulated through the cold water line.