Method, System and Temperature Control of a Heating, Ventilation and Air Conditioning Unit

Abstract

A control assembly for controlling an HVAC unit, and method of controlling an HVAC unit, the HVAC unit having a burner assembly and at least one of a blower, an inducer fan, an air / fuel control system, the method including: measuring a temperature of the burner assembly; comparing the measured temperature of the burner assembly with a predetermined temperature based on firing rate; controlling the HVAC unit to cause the temperature of the burner assembly to come within predetermined limits; wherein the controlling step includes at least one of the steps of: initiating, terminating or modifying, the operation of one or more of the blower, the inducer fan, or modifying an air / fuel mixture of the air / fuel control system, reducing the temperature of the burner assembly to within predetermined limits.

Description

CROSS REFERENCE TO A RELATED APPLICATION[0001]The application claims the benefit of U.S. Provisional Application No. 62 / 949,681 filed Dec. 18, 2019, the contents of which are hereby incorporated in their entirety.BACKGROUND[0002]The subject matter disclosed herein generally relates to heating, ventilation, and air conditioning (HVAC) systems, and more particularly to a method, system and temperature control of an HVAC unit using a temperature sensor.[0003]Heating, ventilation and air conditioning systems are generally operable in response to changes in temperature which may be measured using a bi-metal temperature switch, such as a burner thermal switch (BTS) typically internal or external to an HVAC unit, to turn the unit either on or off based on pre-set temperature limits. However, as an increasing number of HVAC units move away from single stage units, and toward higher efficiency systems such as multi-stage HVAC units (including furnaces), the use of control systems using a BTS...

AI Technical Summary

Benefits of technology

The patent describes a control system for an HVAC unit that includes a burner assembly. The system includes a temperature sensing device that measures the temperature of the burner assembly and a control device that receives the temperature signal. The control device compares the temperature to a predetermined limit and sends a signal to operate the HVAC unit in one of several operational modes based on the temperature. The system can also include sensors that measure the surface or internal temperature of the burner assembly or the air / fuel control system. The system can also include a control device that sends signals to operate the HVAC unit at different rates or for different periods of time. The technical effect of the system is to provide precise control over the temperature of the burner assembly, which helps to improve the efficiency and safety of the HVAC unit.

Problems solved by technology

However, as an increasing number of HVAC units move away from single stage units, and toward higher efficiency systems such as multi-stage HVAC units (including furnaces), the use of control systems using a BTS is impractical because components such as the burner assembly can be hotter during operation at stages less than 100% capacity (i.e., low or modulating).

This operating condition makes it difficult to pass mandatory product safety and performance requirements (e.g., shutting the HVAC system off before it produces unsafe levels of carbon monoxide), without causing the HVAC unit to experience an undesirable nuisance condition and shut the HVAC unit off unexpectedly.

Another drawback of using a BTS is that a BTS will typically activate during a power brownout or blackout because the heat generated in the area of the burner that is normally dissipated by the movement of air is not cooled because the electrically-powered inducer fan that generates airflow, also powers off.

This condition typically leaves excessive heat in the area around the BTS which may cause a BTS pre-set temperature limit to be reached even when a safety issue is not present, resulting in shut down of an HVAC unit.

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