I awoke this morning to find a quantity of water on the normally dry basement floor, which seemed to be coming from my Lennox model# G2003E-75-4.
I pulled the front panels and its bone dry inside.
My daughter, (The child that gives me gray hair, bless her heart), turned the air conditioning on yesterday for the first time since fall, (she's 10), and set the thermostat to fan on, with a temperature setting of 65. I don't know for how long until I realized this and shut it off, and resetting the thermostat controls to auto and 68.
I live in Pittsburgh, the basement is never wet and the furnace sit in the center of the basement; all exterior walls are dry.
The hot water heater near the furnace is dry and seems to be working fine as does the furnace, but this water has me miffed.
Any ideas?
[This furnace was in the house when I moved in in 2008. I had it checked and service in 2011. Filter is changed regularly.]

 

Welcome to the forums.

It sounds like a condensate problem. On the side of your furnace should be a clear plastic tube that drains away the water from the air conditioner coil. The line may be kinked or plugged. It could also be plugged inside the furnace where the drain pan enters.

Check the external line for problems first.

 

Also could be when in a.c. mode it iced up the evap. coil due to cold weather and chunks of ice fell not all caught by pan.If not already dry run t'stat on fan on and with heat calling for awhile.