HVAC Start-Up Delay Control to Prevent Power Spikes

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Solution Overview

Problem

HVAC systems experience power spikes when multiple units start up simultaneously, leading to high energy demands, which can be costly and require manual programming and coordination.

Innovation Solution

A controller for HVAC units that generates an offset delay value to stagger the start-up of components, such as air blowers and compressors, based on a configurable parameter, ensuring that units do not turn on simultaneously, thereby reducing power spikes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If multiple HVAC units start up simultaneously, then the system responds quickly to cooling or heating demands, but power spikes occur causing high energy consumption

Engineering Contradiction:

Improvestart-up response speedVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The system performs preliminary action by implementing a staggered start-up sequence where the outdoor unit begins operation before the indoor unit. This preliminary sequencing prevents simultaneous startup of all components, thereby avoiding power spikes while still meeting cooling or heating demands efficiently

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system applies dynamics by making the start-up timing flexible and adaptive rather than fixed. The controller dynamically adjusts the start-up sequence based on system conditions, implementing variable delay intervals between outdoor and indoor unit activations to optimize power consumption while maintaining responsive performance

Inventive Principle:

Principle #15Dynamics

2Use of energy by moving object

If manual programming is used to prevent power spikes, then power consumption is reduced, but the setup process becomes time consuming and requires coordination

Engineering Contradiction:

Improvepower consumptionVSAvoidsetup complexity

Core Design Contradiction:

Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The system implements self-service by automatically generating and applying staggered start-up sequences without requiring manual configuration. The controller autonomously manages the timing coordination between outdoor and indoor units, eliminating the need for technicians to manually program delay values and coordinate setup across multiple devices

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system uses an intermediary communication protocol between HVAC units to automatically coordinate start-up timing. The controller acts as a mediator that exchanges timing information with other units in the system, enabling automatic staggered activation without manual intervention or complex coordination procedures

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9574785B2Staggered start-up HVAC system, a method for starting an HVAC unit and an HVAC controller configured for the same

Publication Date: 2017.02.21 LENNOX IND INC

AI summary

One aspect of the disclosure describes a controller for a heating, ventilation, and air conditioning (HVAC) unit. In one embodiment, the HVAC controller includes an interface and a processor. In this embodiment, the interface is configured to receive a delay originating signal. In one embodiment, the processor is configured to: (1) automatically generate an offset delay value for the HVAC unit upon receipt of the delay originating signal; (2) apply the offset delay value based on an offset enabled configurable parameter; and (3) delay starting identified components of the HVAC unit based on the offset delay value.