A heat exchanger (e.g., a furnace) for a heating, ventilation, and/or air conditioning (HVAC) system includes a condensate pan having a first opening defined in a surface of the condensate pan. The condensate pan is configured to receive liquid condensate via the first opening, and the first opening comprises a first cross-sectional area. The furnace further includes a pocket comprising a wall circumscribing and defining a second opening. The second opening has a second cross-sectional area greater than the first cross-sectional area of the first opening of the condensate pan. The pocket is configured to be coupled to the surface of the condensate pan such that the wall of the pocket surrounds the first opening in the surface of the condensate pan.