As your gas furnace runs, is there water leaking at the base? Is the furnace's air filter wet, too? There are a few things that could be happening here. But if you have a high-efficiency furnace, here's the most common cause: a condensation leak. We'll explain why a furnace creates condensation, and what's causing it to leak out of your furnace. Note: You'll know if you have a high-efficiency furnace if:
How in the heck does a high efficiency furnace create condensation/water anyway? It's all about how the furnace extracts heat from combustion gases. A lower-efficiency furnace extracts some heat from combustion gases and then quickly vents them out the flue pipe. But a high-efficiency furnace, to extract more heat, has 2 heat exchangers. These allow the furnace to extract heat from the gases for a longer period of time. This causes the combustion gases to cool and then condense. That condensation then exits out your home through a drain. But if that water is pooling around the furnace, there's a problem preventing it from draining properly. Causes of a condensation leak around a high-efficiency furnace
You'll need a furnace technician to diagnose which of these is the issue and then fix it.
Then its flue pipe may be incorrectly sized.
There may be an issue which is causing the humidifier to leak into your furnace. Your humidifier should be getting annual maintenance from a professional to prevent this.
Ragsdale Heating, Air and Plumbing has been serving the Atlanta area for 20 years and can diagnose and repair your furnace's leak issue.