I have a problem with water collecting in the cleanout on my chimney!?

Question

I have a forced air furnace with central air. I only have this problem in the winter, in the summer it stays dry. Rain and snow seem to not be a factor because it still happens even if it has not rained or snowed for weeks! I also have a cap on the chimney.

Answer 1

Is this a new furnace? It may be a condensing furnace in which case the exhaust should exit the house in pvc pipe, or your chimney is to large or long that the flue gas is cooling off before it exits the chimney and condensing into water, in which case you would need a chimney liner. This water is very corrosive and will eat the mortar out of your chimey in time. That is why you see peoples chimneys crumbling. One way to tell if you have a condensing furnace is there will be a little trap or drain on the bottom of your furnace.

Answer 2

I'm guessing that you have a basement, and that the furnace is down there. I would also guess that the basement is damp. That's where, I'm guessing, your water is coming from.

If your furnace is taking in damp air, it turns to steam then condensates as it gets further away from the heat source (furnace). As it goes up the chimney, it cools, falling back down as water. The reason that it only happens in winter is because your A/C unit condensates the water at the unit. It doesn't go up the chimney. Only flue gases from the gas or oil flame go up there. A/C units don't have flue gasses.

I have no idea how to dry the basement other than a dehumidifier, which might be costly to run all the time. There are condensate units that can be installed between the furnace and air vents (usually to ADD moisture to the air), which could probably be configured to work the other way, but I don't know if there are any available to dry out the flue gasses.

Like I said, I really don't have a solution. I'm just giving you a possible cause. Oh, and your basement may stay more damp in winter, even though that's usually when the air is drier, because there is less evaporation of rain/snow and the ground may be frozen where you live. This blocks the usual drainage that occurs in warmer weather. Also check to make sure you have adequate drainage away from the foundation. Depending on where you live, winter may cause more or less water infiltration.

Climates where the snow doesn't melt until Spring shouldn't see any increased seapage until it gets warmer, but places like Tennessee, where the snow melts after a couple of days, will see increased seapage in winter (the ground never really freezes solid)

Answer 3

Sounds like condensation probably building up in the chimney during the cold and damp months. Build a fire in it to dry it out as needed.

Answer 4

Have someone put a cap about 6"above it, this will keep the rain and snow out of it.