Furnace for a rooftop unit

Patent metadata

Field	Value
Publication number	US-11486604-B2
Application number	US-201916709657-A
Country	US
Kind code	B2
Filing date	Dec 10, 2019
Priority date	Aug 1, 2016
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

A heating, ventilating, and air conditioning (HVAC) system includes a furnace having a primary heat exchanger and a secondary heat exchanger, where the primary heat exchanger and the secondary heat exchanger form a heat exchange relationship between an airflow and an exhaust gas, and where the primary heat exchanger is positioned upstream of the secondary heat exchanger, a burner configured to generate the exhaust gas, a sensor configured to monitor an ambient temperature, and a control system configured to receive feedback from the sensor, compare the feedback to a threshold, operate the furnace in a first mode when the ambient temperature exceeds the threshold, and operate the furnace in a second mode when the ambient temperature is at or below the threshold, where the furnace operates above a condensation temperature when in the second mode, such that the exhaust gas does not condense when operating in the second mode.

First claim

The invention claimed is:

1. A furnace of a heating, ventilation, and air conditioning (HVAC) system, comprising:
a burner configured to generate a heating fluid;
a primary heat exchanger configured to receive the heating fluid from the burner and place the heating fluid in a heat exchange relationship with an air flow directed through an air flow path of the furnace, wherein the primary heat exchanger comprises a first number of first heat exchange tubes, wherein at least a portion of the first heat exchange tubes extends along an axis;
a secondary heat exchanger configured to receive the heating fluid from the primary heat exchanger and place the heating fluid in an additional heat exchange relationship with the air flow directed through the air flow path of the furnace, wherein the secondary heat exchanger comprises a second number of second heat exchange tubes that is greater than the first number, wherein the second heat exchange tubes extend along the axis; and
a collector fluidly coupled to the primary heat exchanger and the secondary heat exchanger, wherein the collector is disposed between the first heat exchange tubes and the second heat exchange tubes along the axis to fluidly couple the first heat exchange tubes to the second heat exchange tubes, such that the first heat exchange tubes are coupled to the collector at a first side of the collector, and the second heat exchange tubes are coupled to the collector at a second side of the collector opposite the first side.

2. The furnace of claim 1 , wherein the secondary heat exchanger is positioned downstream of the primary heat exchanger relative to a flow direction of the air flow through the air flow path.

3. The furnace of claim 1 , wherein a first diameter of each first heat exchange tube is greater than a second diameter of each second heat exchange tube.

4. The furnace of claim 3 , wherein the first diameter of each first heat exchange tube is at least twice as great as the second diameter of each second heat exchange tube.

5. The furnace of claim 1 , wherein each first heat exchange tube of the primary heat exchanger comprises a bend, and each second heat exchange tube of the secondary heat exchanger is linear.

6. The furnace of claim 1 , comprising an additional collector fluidly coupled to the secondary heat exchanger, wherein the additional collector is configured to receive the heating fluid from the secondary heat exchanger.

7. The furnace of claim 6 , comprising an exhaust outlet fluidly coupled to the additional collector and configured to discharge the heating fluid from the furnace.

8. The furnace of claim 7 , wherein the additional collector is configured to collect condensate generated by the furnace, and wherein the furnace comprises a condensate drain port fluidly coupled to the additional collector and configured to discharge condensate collected by the additional collector from the furnace.

9. The furnace of claim 6 , comprising a barrier configured to separate the air flow path from a burner compartment of the furnace, wherein the burner is disposed within the burner compartment, the first heat exchange tubes are coupled to the barrier, and the additional collector is coupled to the barrier.

10. A furnace of a heating, ventilation, and air conditioning (HVAC) system, comprising:
a burner configured to generate a heating fluid;
a primary heat exchanger positioned within an air flow path of the furnace and configured to receive the heating fluid from the burner and place the heating fluid in a heat exchange relationship with an air flow directed through the air flow path, wherein the primary heat exchanger comprises first tubes, each first tube having a first diameter, wherein at least a portion of the first tubes extends along an axis;
a secondary heat exchanger positioned within the air flow path and configured to receive the heating fluid from the primary heat exchanger and place the heating fluid in an additional heat exchange relationship with the air flow directed through the air flow path, wherein the secondary heat exchanger comprises second tubes, each second tube having a second diameter, wherein the first diameter is greater than the second diameter, and wherein the second tubes extend along the axis; and
a collector disposed between the first tubes and the second tubes along the axis to fluidly couple the first tubes to the second tubes, such that the collector is coupled to the first tubes at a first side of the collector and coupled to the second tubes at a second side of the collector opposite the first side.

11. The furnace of claim 10 , wherein the secondary heat exchanger is positioned within the air flow path downstream of the primary heat exchanger relative to a flow direction of the air flow through the furnace.

12. The furnace of claim 10 , wherein the collector is configured to direct the heating fluid from the first tubes to the second tubes.

13. The furnace of claim 12 , wherein the collector is a first collector, and the furnace comprises an exhaust outlet and a second collector fluidly coupled between the secondary heat exchanger and the exhaust outlet, wherein the second collector is configured to direct the heating fluid from the second tubes to the exhaust outlet.

14. The furnace of claim 13 , comprising a condensate drain port fluidly coupled to the second collector, wherein the second collector is configured to collect condensate generated from the heating fluid, and the condensate drain port is configured to discharge the condensate from the second collector.

15. The furnace of claim 10 , wherein a first number of the first tubes is less than a second number of the second tubes.

16. A furnace of a heating, ventilation, and air conditioning (HVAC) system, comprising:
an air flow path configured to direct an airflow therethrough;
a first plurality of heat exchanger tubes disposed within the air flow path and configured to direct a heating fluid therethrough, wherein at least a portion of the first plurality of heat exchanger tubes extends along an axis;
a first collector disposed within the airflow path, wherein a first side of the first collector is coupled to the first plurality of heat exchanger tubes and is configured to receive the heating fluid from the first plurality of heat exchanger tubes;
a second plurality of heat exchanger tubes disposed within the air flow path, wherein the second plurality of heat exchanger tubes extends along the axis, wherein the second plurality of heat exchanger tubes is coupled to a second side of the first collector opposite the first side, is configured to receive the heating fluid from the first collector, and is configured to direct the heating fluid therethrough, wherein the first collector is disposed between the first plurality of heat exchanger tubes and the second plurality of heat exchanger tubes along the axis to fluidly couple the first plurality of heat exchanger tubes to the second plurality of heat exchanger tubes;
a second collector coupled to the second plurality of heat exchanger tubes, wherein the second collector is configured to receive the heating fluid from the second plurality of heat exchanger tubes;
an exhaust outlet coupled to the second collector and configured to discharge the heating fluid from the furnace; and
a condensate drain port coupled to the second collector, wherein the condensate drain port is configured to discharge condensate formed from the heating fluid and collected in the second collector from the furnace.

17. The furnace of claim 16 , wherein each heat exchanger tube of the first p

Assignees

• Johnson Controls Tech Co
• Johnson Controls Tyco IP Holdings LLP

Inventors

• Wilson Stephen C

Classifications

• F28F1/42

  the means being both outside and inside the tubular element · CPC title

• F24D2220/042

  Temperature sensors · CPC title

• Y02B30/00

  Energy efficient heating, ventilation or air conditioning [HVAC] · CPC title

• F24H9/18 Primary

  Arrangement or mounting of grates or heating means · CPC title

• F28F17/005

  Means for draining condensates from heat exchangers, e.g. from evaporators (F28B9/08 takes precedence) · CPC title