Systems and methods for providing airflows across a heat exchanger

1. A heating, ventilation, and/or air conditioning (HVAC) system, comprising:

a return air section of an HVAC unit configured to receive a return airflow from a conditioned space;

an outdoor air section of the HVAC unit configured to receive an outdoor airflow from an environment surrounding the HVAC unit, wherein the return air section and the outdoor air section are configured to discharge airflow toward a mixing box of the HVAC unit in parallel with one another;

a heat exchanger positioned within the HVAC unit and downstream of the mixing box relative to a flow direction of airflow in the HVAC unit; and

a panel dividing the return air section and the outdoor air section, wherein the panel comprises a bypass damper actuatable to enable mixing of the return airflow and the outdoor airflow to produce a mixed airflow in the outdoor air section.

2. The HVAC system of claim 1 , wherein the outdoor air section comprises a damper configured to selectively control flow rate of the outdoor airflow from the environment into the outdoor air section.

3. The HVAC system of claim 2 , comprising an exhaust fan of the return air section configured to drive a portion of the return airflow out of the return air section and into the environment.

4. The HVAC system of claim 1 , wherein the heat exchanger is an evaporator coil.

5. The HVAC system of claim 4 , wherein the outdoor air section comprises a first height, the return air section comprises a second height, and the evaporator coil spans a total height comprising a sum of the first height and the second height.

6. The HVAC system of claim 4 , wherein the evaporator coil comprises a first portion corresponding to the return air section and a second portion corresponding to the outdoor air section, wherein the HVAC system is configured to adjust a position of the bypass damper such that substantially equal amounts of airflow are provided across the first portion and the second portion of the evaporator coil.

7. The HVAC system of claim 1 , wherein the outdoor air section comprises a damper configured to selectively control flow rate of airflow from the outdoor air section to the heat exchanger of the HVAC unit.

8. The HVAC system of claim 1 , wherein the return air section comprises a damper configured to selectively control flow rate of airflow from the return air section to the heat exchanger of the HVAC unit.

9. The HVAC system of claim 1 , comprising a filter disposed within the HVAC unit downstream of the return air section and the outdoor air section relative to the flow direction of airflow in the HVAC unit.

10. The HVAC system of claim 1 , wherein the mixing box of the HVAC unit is positioned downstream of the outdoor air section and the return air section relative to the flow direction of airflow in the HVAC unit.

11. A heating, ventilation, and/or air conditioning (HVAC) unit, comprising:

a refrigerant circuit comprising a heat exchanger and configured to flow a refrigerant therethrough;

a return air section comprising a return air inlet configured to receive a return airflow from a conditioned space and a return air outlet configured to output airflow toward the heat exchanger;

an outdoor air section comprising an outdoor air inlet configured to receive an outdoor airflow from an environment surrounding the HVAC unit and an outdoor air outlet configured to output airflow toward the heat exchanger wherein the return air outlet and the outdoor air outlet are configured to output airflow toward the heat exchanger in parallel with one another; and

a panel dividing the return air section and the outdoor air section, wherein the panel comprises a bypass damper actuatable to fluidly couple the outdoor air section and the return air section and enable mixing of the outdoor airflow and the return airflow within the outdoor air section, the return air section, or both, to produce a mixed airflow.

12. The HVAC unit of claim 11 , wherein the HVAC unit comprises a rooftop unit having the refrigerant circuit, the return air section, the outdoor air section, and the panel.

13. The HVAC unit of claim 11 , comprising an actuator configured to adjust a position of the bypass damper and a controller configured to adjust operation of the actuator.

14. The HVAC unit of claim 13 , comprising an outdoor air damper actuatable to control an amount of the outdoor airflow that enters the HVAC unit from the environment, wherein the controller is configured to adjust the position of the bypass damper based on a position of the outdoor air damper.

15. The HVAC unit of claim 13 , comprising:

a return air damper actuatable to control an amount of airflow passing from the return air section toward the heat exchanger;

an outdoor air damper actuatable to control an amount of airflow passing from the outdoor air section toward the heat exchanger; and

a mixing box disposed downstream of the return air section and the outdoor air section and upstream of the heat exchanger relative to a flow direction of airflow in the HVAC unit.

16. The HVAC unit of claim 11 , comprising an air filter of the HVAC unit, wherein the air filter is positioned downstream of the return air section and the outdoor air section and upstream of the heat exchanger relative to a flow direction of airflow in the HVAC unit.

17. The HVAC unit of claim 11 , comprising an exhaust air damper actuatable to control an amount of an exhaust airflow that exits the return air section to the environment, wherein a controller of the HVAC unit is configured to adjust a position of the bypass damper based on a position of the exhaust air damper.

18. A heating, ventilation, and/or air conditioning (HVAC) unit, comprising:

a heat exchanger;

a pre-mixing section comprising a return air section configured to receive a return airflow from a conditioned space and comprising an outdoor air section configured to receive an outdoor airflow from an environment surrounding the HVAC unit, wherein the return air section and the outdoor air section are configured to discharge airflow toward the heat exchanger in parallel; and

a panel disposed within the pre-mixing section and dividing the return air section and the outdoor air section, wherein the panel comprises a bypass damper actuatable to enable the return airflow to enter the outdoor air section, the outdoor airflow to enter the return air section, or both,

wherein the HVAC unit is configured to mix the return airflow and the outdoor airflow within the pre-mixing section to form a mixed airflow and provide the mixed airflow to the conditioned space.

19. The HVAC unit of claim 18 , wherein the heat exchanger is disposed downstream of the pre-mixing section, wherein the heat exchanger is configured to condition the mixed airflow for the conditioned space.

20. The HVAC unit of claim 19 , comprising an air filter disposed between the pre-mixing section and the heat exchanger.

21. The HVAC unit of claim 19 , wherein a first portion of the heat exchanger spans a height of the return air section, and a second portion of the heat exchanger spans a height of the outdoor air section.

22. The HVAC unit of claim 18 , comprising a return air damper of the return air section and an outdoor air damper of the outdoor air section, wherein the return air damper and the outdoor air damper are each configured to regulate flow of the mixed airflow exiting the pre-mixing section.

23. The HVAC unit of claim 18 , wherein the HVAC unit is configured to mix the return airflow and the outdoor airflow within the outdoor air section to form the mixed airflow within the outdoor air section.

24. The HVAC unit of claim 18 , comprising:

an actuator configured to adjust a position of the bypass damper; and

a controller configured to adjust operation of the actuator.

25. The HVAC unit of claim 24 , wherein the controller is configured to adjust the position of the bypass damper based on a position of another damper of the HVAC unit.