Air Handler Water-Flow Control to Prevent Pump Cavitation
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Solution Overview
Problem
Conventional systems for heating air using hot water often face issues with inadequate water flow and temperature, leading to cavitation of air handler pumps and reduced energy transfer, resulting in cold air being blown into spaces instead of heated air.
Innovation Solution
A method and system where a controller monitors water flow from a water heater and adjusts the operation of the air handler's pump and blower/fan based on the water flow signal, ensuring sufficient hot water supply by initiating or terminating their operation only when the water flow meets a selected level, typically above 90% of the water heater's capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the water heater supplies hot water to the air handler, then heated air can be generated for space heating, but water draw may exceed the water heater's output flow capacity leading to insufficient water flow
Solution Approach 1:
The system performs preliminary action by checking water flow conditions before initiating the air handler pump operation. The controller monitors water flow from the water heater and only allows the air handler pump to operate when sufficient water flow is detected, preventing cavitation and ensuring proper heating operation.
Solution Approach 2:
The system uses feedback by continuously monitoring water flow conditions and using this information to control the air handler pump and blower operations. The controller receives feedback about water flow adequacy and adjusts system operation accordingly, ensuring heated air is only delivered when sufficient hot water is available.
2Duration of action of stationary object
If the air handler pump operates with insufficient water flow, then the pump may cavitate and its life is shortened, but the system cannot deliver heated air
Solution Approach 1:
The system checks water flow conditions before allowing the pump to operate. By performing this preliminary check, the system prevents cavitation damage to the pump impeller while ensuring that heated air can be delivered when water flow is sufficient.
Solution Approach 2:
The controller continuously monitors water flow conditions and uses this feedback to control pump operation. When water flow falls below the threshold, the controller stops the pump to prevent cavitation, thereby extending pump life while maintaining the ability to deliver heated air when conditions are favorable.
3Loss of energy
If low or no water flow is supplied to the air handler, then energy transfer through the heat exchanger is reduced, but the system avoids pump cavitation
Solution Approach 1:
The system uses feedback control to monitor water flow conditions and adjust operations accordingly. When sufficient water flow is detected, the system operates the pump and blower to maximize energy transfer efficiency. When water flow is insufficient, the system shuts down operations to maintain reliability, preventing both cavitation damage and inefficient energy transfer.
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 approach prevents cavitation and ensures consistent delivery of heated air by maintaining adequate water flow and temperature, extending the life of the pump and improving energy transfer efficiency.
Implementation Method 1
an air handler comprising a blower/fan and an air handler heat exchanger to generate heated air from hot water
Implementation Method 2
a pump operative to flow water out of the water heater, and a controller connected to monitor water flow indicia
Data Source
AI summary
A method controls an air handler that generates heated air from hot water generated by a water heater. The method includes generating a signal in the presence or absence of an indicia of water flow associated with the water heater; initiating operation of a pump associated with the air handler when the signal indicates that water flow associated with the water heater is at least at a selected level to supply hot water to the air handler sufficient to generate heated air; and/or terminating operation of the pump and/or a blower/fan associated with the air handler when the presence or absence signal indicates that the water flow associated with the water heater is less than the selected level.