Tankless Water Heater Additive Dosing for Precise Scale Control
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Solution Overview
Problem
Existing systems for preventing limescale buildup in tankless water heaters are inefficient due to inconsistent dosing of scale-preventing additives, often resulting in either underdosing or overdosing, which can lead to reduced efficacy and non-compliance with regulations.
Innovation Solution
A liquid dosing system that includes a pump, reservoir, and dosing device with a controller to precisely dispense additives like sodium hexametaphosphate into the water circuit based on flow data, ensuring a consistent concentration of 5 ppm, regardless of water pressure and flow rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive addition methods (venturi or diffusion) are used to add sodium hexametaphosphate to water, then the system is simple in structure, but the dosing precision deteriorates due to sensitivity to water flow rate and supply water pressure changes
Solution Approach 1:
The patent implements a feedback control system where a flow sensor detects the actual water flow rate and supply pressure, and the controller adjusts the pump operation and dosing device accordingly to maintain the target concentration of 5 ppm sodium hexametaphosphate despite variations in water conditions
Solution Approach 2:
The patent replaces passive mechanical addition methods (venturi or diffusion) with an active dosing system using a pump and controllable dosing device, allowing precise electronic control of additive delivery independent of water flow variations
2Device complexity
If passive addition methods are used, then the device complexity is low, but the reliability deteriorates due to inconsistent dosing that can lead to underdosing or overdosing
Solution Approach 1:
The flow sensor continuously monitors water flow rate and supply pressure, providing feedback to the controller which adjusts the dosing rate in real-time to maintain consistent 5 ppm concentration, preventing both underdosing and overdosing conditions
Solution Approach 2:
The system performs preliminary measurement of water flow rate and pressure before dosing, allowing the controller to pre-calculate the required dosing rate to achieve the target concentration, ensuring reliable dosing from the start of operation
3Ease of operation
If additive is added continuously without flow-based control, then the system operation is simple, but the loss of substance increases due to additive waste from overdosing during high flow conditions
Solution Approach 1:
The flow sensor provides real-time feedback on actual water consumption, allowing the controller to adjust the dosing rate proportionally, ensuring additive is added at the correct rate and preventing waste during high flow conditions while maintaining adequate concentration during low flow
Solution Approach 2:
The system dynamically changes the dosing rate parameter based on measured water flow rate and pressure conditions, adjusting the additive delivery rate to match actual water consumption and eliminate unnecessary additive waste
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 effectively prevents limescale formation in tankless water heaters by maintaining a precise additive concentration, enhancing efficiency and compliance with regulations while minimizing additive waste.
Implementation Method 1
a pump configured to pump water through the fluid circuit
Implementation Method 2
a dosing device configured to dispense the additive into the fluid circuit
Data Source
AI summary
A liquid dosing system is disclosed and can include an inlet conduit and an outlet conduit. The inlet and outlet conduits can each be configured to fluidly communicate a heat exchanger of a water heater. The liquid dosing system can include one or more connector conduits configured to fluidly connect the inlet conduit and the outlet conduit to define a fluid circuit by at least the inlet conduit, the heat exchanger, the outlet conduit, and the one or more connector conduits. The liquid dosing system can include a pump configured to pump water through the fluid circuit, a reservoir configured to store an additive, and a dosing device configured to dispense the additive into the fluid circuit.