Connection box for condensate pumps in air-conditioning units

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Solution Overview

Problem

Existing air-conditioning systems face challenges in efficiently managing condensate overflow, particularly in commercial settings, where manual emptying is impractical, and condensate pumps may malfunction, leading to system shutdowns or water damage, while integration with building management systems requires complex re-wiring and technical knowledge.

Innovation Solution

A connection box with clearly labeled terminal blocks and a relay circuit that simplifies the installation of condensate pumps by allowing external connections to a condensate pump and AC unit, enabling safe operation and integration with or without a building management system, using a normally closed or open configuration to manage high water levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a condensate pump is used to empty the reservoir, then the reservoir can be smaller and the AC unit more appealing, but the pump may malfunction and cause water damage

Engineering Contradiction:
Improvereservoir volumeVSAvoidcondensate pump reliability
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The system is segmented into distinct functional components: the reservoir, the condensate pump, the connection box with relay circuit, and the control system. This segmentation allows the reservoir to be smaller while maintaining safety through independent monitoring and control mechanisms.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The relay circuit is configured to cut off power to the evaporator before water damage can occur. The high water level switch and relay circuit prepare the system in advance by establishing automatic shutdown capability, so that when the pump malfunctions, the power is already cut off or can be quickly cut off to prevent damage.

Inventive Principle:
Principle #10Preliminary action

2Object-affected harmful factors

If a water level switch is fitted to the condensate pump, then overflow risk is reduced, but the system becomes less reliable due to moving parts in the pump

Engineering Contradiction:
Improveoverflow riskVSAvoidsystem reliability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The relay circuit acts as an intermediary between the water level switch and the evaporator power supply. The relay contains the moving parts (switching mechanism) separate from the pump, allowing the pump to remain simple and reliable while still providing overflow protection through the relay's switching action.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system replaces direct mechanical coupling between the water level switch and pump control with an electromagnetic relay system. This substitution allows the water level detection to control power delivery through the relay circuit, reducing mechanical complexity in the pump itself while maintaining protection capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Object-affected harmful factors

If the AC unit is shut down on high water level alert, then water damage is prevented, but the AC unit cannot operate in scenarios where overflow risk is acceptable

Engineering Contradiction:
Improvewater damage preventionVSAvoidsystem adaptability
Core Design Contradiction:
Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The relay circuit is designed to be reconfigurable between normally closed and normally open states, allowing the system to dynamically adapt its shutdown behavior. This enables the same hardware to serve both safety-critical applications (where shutdown is required) and flexible applications (where continuous operation is preferred).

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system allows changing the operational parameter of the relay (normally closed vs. normally open state) to adapt to different application requirements. This parameter change enables the system to switch between safety-first operation and flexibility-first operation without hardware modification.

Inventive Principle:
Principle #35Parameter changes

4Extent of automation

If the AC unit and condensate pump are integrated into a BMS, then centralized control is achieved, but complex re-wiring is required

Engineering Contradiction:
Improvecentralized controlVSAvoidwiring complexity
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The complex wiring and control logic are extracted from the AC unit and condensate pump themselves and consolidated into a separate connection box. This externalization of complexity allows the main AC unit and pump to remain simple devices that can be easily integrated into a BMS without requiring internal modifications or complex re-wiring.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The connection box serves as an intermediary device between the AC unit, condensate pump, and BMS. It provides standardized connection terminals and handles the complex control logic, allowing straightforward integration with BMS while shielding the AC unit and pump from wiring complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

5Extent of automation

If installers re-wire the electronics to integrate with BMS, then centralized management is enabled, but installation time and technical knowledge requirements increase

Engineering Contradiction:
Improvecentralized managementVSAvoidinstallation time
Core Design Contradiction:
Extent of automationVSLoss of time

Solution Approach 1:

The BMS integration functionality is extracted into a separate connection box with pre-configured terminals and circuitry. This allows installers to simply connect pre-labeled wires to the connection box terminals rather than performing complex re-wiring of the AC unit and pump, dramatically reducing installation time and skill requirements while maintaining full BMS integration capability.

Inventive Principle:
Principle #2Taking out (Extraction)

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

Facilitates safe and efficient installation of condensate pumps in AC units, preventing overflow and enabling integration with building management systems without re-wiring, reducing installation errors and ensuring reliable operation.

Implementation Method 1

a relay circuit configured to cut off power supply to the evaporator in the event of a high water level in the condensate reservoir

Methodology Applied
Scientific EffectRelay: Relay

Data Source

PatentEP3692311B1Connection box for condensate pumps in air-conditioning units
Publication Date: 2026.01.21 ASPEN PUMPS LIMITED
  • EP3692311B1 patent drawingFigure 1A~1C
  • EP3692311B1 patent drawingFigure 2
  • EP3692311B1 patent drawingFigure 3

AI summary

The connection box of the present invention provides a simple and safe method to integrate an AC unit and condensate pump into a larger building management system. This is possible because the circuit is configured to require high water level sensors are connected to the connection box in order for power to be provided to operate the AC unit. An installer only has to connect the external wires of the AC unit, condensate pump and building management system to the respective designated connection terminals within the connection box. The designated terminal connections provide a clearly labelled instruction to an installer and aid safe and proper installation of AC units and remove the need to re- wire the internal wiring of the AC unit.