Furnace/Water leak conundrum

[JJ Husker]

Here's the deal. We had a torrential rain storm this afternoon. I have a forced air furnace with AC in the basement. It also has a humidifier on it. There is water inside the furnace, on the floor around it, the water destroyed the furnace filter. I cannot figure out where the water is coming from. My only theory is that it came in down the inside of the double wall flue pipe. However, I see no signs of water in the flue blower housing which is directly below the flue pipe. It does not appear to have come down the outside of the flue (which would signal a roof leak around the flue pipe). I have a rain cap on the flue pipe. I do not believe it is coming from the humidifier or water lines in the area.

Does anyone think that if it rained heavy enough and blew sideways hard enough (which it did) that any significant amount of rain water could come down the inside of the flue pipe? That is all I can think it could possibly be. Can anybody confirm that or offer an alternate suggestion?

 

[C N Red]

Check your condensate. Mine got clogged up and made quite a mess. Hvac guy said my pan was really dirty to which led to clog.

 

[JJ Husker]

Check your condensate. Mine got clogged up and made quite a mess. Hvac guy said my pan was really dirty to which led to clog.

That's a good idea but I checked that and my condensate drain pipe is fine.....unless there is something internal but the drain seems to be clear and trickling water to the floor drain like normal.

I am 99% sure it had something to do with the ridiculous rainfall we had this afternoon. I got all the water shop vac'd up and dried out the inside best I could. Took the doors off, filter out, ran the furnace fan and blew another fan on it for about an hour. Seems to have dried up and I don't hear any drip drip drip anymore. I'm just still confused as to how that much water (guessing half to a full gallon) got into the furnace. I'll check again in the morning. If it's all wet again (and it hasn't rained anymore...) then I'll probably call an HVAC outfit.

If there's one thing that I hate it's water/roof leaks. They're often very difficult to pinpoint.

 

[Kiyoat Husker]

It still could be the drain. Just because water is flowing through the tube doesn't mean it isn't also backed up. Open it up to look at the pan. Mine was clogged with rusty particulate.

 

[JJ Husker]

Thank you C N Red and IA State Husker, I think you guys are right.
Checked it this morning and had more water again. The condensate drain outlet has two ports, one connected to the drain pipe and one has a plug. I pulled the plug out and water poured out of it. So the one going to the drain pipe is plugged up somewhere. I'm going to pull a panel off the AC coil to get to the drain pan and clean everything up. Of course it won't be that simple because to get the panel off I have to remove the exhaust flue ducts to the furnace and my water heater. I'm also going to run another 3/4" PVC drain line from that 2nd drain port. I'm pretty darned sure that should take care of things. The timing of this showing up with the ungodly heavy rain caused me to think that was the culprit. But it has been unusually humid here the past week or so, so I'm sure that is causing more condensate than normal, thus the partially plugged drain not being able to handle the water. Thanks again for the input.

I'd give more +1's if I could....

 

[JJ Husker]

Sure enough, that was the problem. Took off work a bit early today to go home and fix it and found that the little drain hole was partially plugged with rusty/scaly debris. Cleaned out the pan and the hole so should be good for awhile now. That 2nd drain port is actually a bit higher on the pan so it must be a secondary overflow drain. The drain hole for it is actually a little large than the lower primary drain. So now if I ever see water coming out of it I'll know I need to clean it out again and hopefully I don't ever have this issue again. Thanks guys

 

[JJ Husker]

The best part is my wife rolled her eyes at me when I said I was posting the question on Huskerboard. Sh!t gets done when you put it to the experts....ha.

 

[4skers89]

I think it should be a law that condensate pans be made out of stainless steel. When mine rusted out a couple of years ago I fabricated one out of stainless. It will last longer than the rest of the unit

 

[JJ Husker]

I think it should be a law that condensate pans be made out of stainless steel. When mine rusted out a couple of years ago I fabricated one out of stainless. It will last longer than the rest of the unit

My pan was actually fiberglass. The rust was from the A frame cooling coil. I was totally expecting to find a rusted out galvanized pan. But yeah, stainless steel instead of galvanized steel would be a huge improvement.