Calling HVAC experts...
 

I'm very happy I decided to change my air filter tonight. When I did so, I looked down into the pan surrounding my heater on the floor and there were a few inches of water in there. I'm pretty sure it was dry two weeks ago when I got back from CA and had to fiddle with my heater to get it to come on. I used a sucker piston that I usually use when I overfill a car with oil. I took out nine quarts of water!!!

Last Feb., on about the coldest day when I was home sick, my heater went out. HVAC guy came and fixed it and said it had gone out because that water level had risen to the kill switch. I can't remember if I asked him what causes that. But it would have happened again very soon, had I not discovered all that water tonight. What causes that? I'm guessing condensation. But how can it be so much so fast? I think I'll call them again mid-week and have them come out Thurs. or Fri. when I'm working from home. But is there anything I can DIY here? Furnace is gas, has no pilot light and is about five yrs. old.

Condensation. Isn't there a condensate drain? Plugged up?

Condensation comes from running the A/C, not heat. There is suppose to be a drain or an electric pump to get the water out of there.

Is this a 95% efficient furnace? It won't have a gas vent pipe. Those units create condensation from the combustion. If the water cannot gravity drain, it needs a condensate pump. Those pumps can fail. I'm not certain a supply house will sell this part to you.

High efficiency furnaces have drains also. These should drain into a condensate pump, or to your sump pump.

Pop the cover and look around, follow the drain lines. At about 5 years old, I replaced most of the clear plastic drains on my furnace.

I found the drain line and pulled the pvc pipe away to check for blockage. Looked clear to me and the L at the bottom ran downhill. So I poured about 1/3 liter of tap water down it and heard it all rush down and along the long drainl. Pretty sure it ain't clogged. I called the local HVAC place that serviced the unit before and the guy said it had to be from when I had the a/c on. That was a good three weeks ago last and I'm sure the drain pan was bone dry when I checked it after I got back from CA on 10/28. He said there's no way the heater could have produced that condensation and there was no other water source in the unit. I guess I'll just have to keep an eye on it and be sure to have it serviced when a/c season approaches.

Sometimes the condensate trap collects crap that will prevent the condensate to run to the drain. It can back up.That could be the source of the water.