I changed my filter the other day and noticed a pool of water in the bottom of the furnace, below the filter. The humidifier has been off so that's not the issue. I removed the furnace panels and see water coming off the hoses that seem to collect to the intake/exhaust pipes (picture below). BTW, this is a high efficiency furnace, and is only 3 years old. The condensation drain pipe is bone dry so I thought perhaps it could be clogged, but would it drain during the winter when humidifier is off? Fortunately the electronics are dry. Any ideas on what's going on would be greatly appreciated. Here are a couple photos
It is indeed condensate water, high efficiency furnaces wring water all year long (more so during heating, but A/C in summer too).
What has happened is the condensate collection point (on the inside of where the external PVC drain runs) has cracked. It is a very brittle and cheap plastic, just saw this on another customers furnace. It acts like a little trap, holding water until it overflows into the PVC to drain.
Possibly the PVC got kicked and the force made its way back to the box (good luck getting a show of hands for this one)..
In any case, your furnace vendor will likely have one in stock.