Internal recirculation with low pulse fire control

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Solution Overview

Problem

Existing tankless water heaters face challenges in delivering low flow and heated water efficiently and preventing freezing, particularly in conditions of low or no water flow, while maintaining heat exchange performance and reducing costs.

Innovation Solution

A method and appliance utilizing a larger volume coil-type heat exchanger with a burner that activates for pulse fire durations based on sensed conditions, such as temperature and flow, to heat water efficiently and avoid freezing, potentially eliminating the need for electric heating elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a conventional tankless water heater uses continuous or high-power heating, then heating capacity is sufficient, but energy consumption increases and control precision deteriorates

Engineering Contradiction:

Improveenergy consumptionVSAvoidcontrol precision

Core Design Contradiction:

Use of energy by moving objectVSEase of operation

Solution Approach 1:

The patent implements periodic pulsed firing of the burner instead of continuous operation. The controller activates the burner in discrete pulses with specific durations (e.g., 1-5 seconds) separated by idle periods, creating a periodic heating action that maintains water temperature while reducing overall energy consumption. This periodic action allows precise control of heat input to match low flow demand.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system dynamically adjusts burner pulse duration and frequency based on real-time temperature sensor feedback and flow rate detection. The controller modifies pulse parameters adaptively to maintain optimal water temperature, enabling precise control despite using intermittent rather than continuous heating. This dynamic response resolves the contradiction between energy savings and control precision.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If the water supply volume in the heat exchanger is increased, then freezing prevention improves, but heat exchange performance may deteriorate

Engineering Contradiction:

Improvefreezing preventionVSAvoidheat exchange performance

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The system performs preliminary heating by detecting low flow conditions and activating the burner before the water temperature reaches freezing point. The controller monitors temperature sensors and initiates heating pulses in advance, ensuring the water supply remains above freezing temperature. This preliminary action prevents freezing while maintaining compact heat exchanger design for efficient heat exchange.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If pulse fire duration is extended, then heating efficiency improves, but risk of overheating increases

Engineering Contradiction:

Improveheating efficiencyVSAvoidoverheating risk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system employs temperature sensors positioned to monitor water temperature during and between pulses. The controller receives feedback from these sensors and adjusts subsequent pulse duration and timing accordingly. If temperature approaches the target threshold, the controller reduces or extends the idle period between pulses, preventing overheating while maintaining heating efficiency through optimized pulse timing based on real-time feedback.

Inventive Principle:

Principle #23Feedback

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 solution enables efficient delivery of low flow heated water and prevents freezing by optimizing heat transfer and reducing reliance on electric elements, enhancing operational efficiency and cost-effectiveness.

Implementation Method 1

a heat exchanger configured to transfer heat to the water supply from a burner

Methodology Applied

Scientific EffectHeat transfer: Convection

Implementation Method 2

transfer heat to the water supply from a burner when the water supply is contained in the heat exchanger

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

a burner configured to generate heat for transfer to the water via the heat exchanger

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS20260029162A1Internal recirculation with low pulse fire control

Publication Date: 2026.01.29 BRADFORD WHITE CORP

AI summary

A method of heating water in a tankless water heating appliance in conditions of low water flow or no water flow is disclosed. A water supply is introduced into a heat exchanger configured to transfer heat to the water supply from a burner when the water supply is contained in the heat exchanger. A pulse fire duration is determined for the burner and a pre-defined condition of the water supply is sensed. When the pre-defined condition is sensed, the burner is activated to fire for the pulse fire duration, and the burner is deactivated after the pulse fire duration is elapsed. The pre-defined condition of the water supply is monitored, such that when the pre-defined condition is sensed again, the burner is activated to fire for another pulse fire duration, and the burner is deactivated after the another pulse fire duration is elapsed.