Our furnace has worked great all winter but now it is putting out air that feels wet and heavy. It makes me cough and it feels hard to breath. It's like water in the air. Like the furnace is not removing moisture. It's like a humidifier running but we do not have one on the furnace and not using one in the house either. Even the cat acts like it is affecting his breathing. We have a Lennox gas furnace it's 2 years old and runs on propane. Anyone have any ideas? I can't stand this and am afraid it might affect our health.

Considering that the furnace recycles the air in the home, the moisture may already be in the air, and being "amplified" so to speak, when heated causing you to notice more.

Otherwise, you will need to open the access panels to the fan compartment of the furnace to inspect and see if there is any water or condensation collecting. Check to see if there are any way you can look inside the duct work looking for water.

Is there any location that the duct work passes through that may be moist, such as a crawl space, and drawing that moist air in?

You may want to go out and get a device that measures relative humidity, to be sure that what you perceive is true, and not some other anomaly.

I would have a professional check this out as soon as possible. Lennox did have some problems with propane furnaces. Call the deqaler that installed the furnace and have it checked!!

Thanks guys! I had the furnace shut off all last night and this morning. Finally had to turn it on it was too cold in the house. I took the door off the furnace and looked inside while it was running. I saw 2 windows where you could see the flame. The flame on the left was blue, the flame on the right was real orange looking. Does this mean anything? Also we do have a crawl space in part of the basement which I have always hated. However I did not feel or smell this wet air with the furnace turned off.
I ran the de-humidifier today and that did not help that wet air feel and smell at all. When I turned the furnace back on it's all back again. I will be calling the furnace guy first thing Monday! Thanks again!

The blue flame is exactly what you should see, the orange flame means that the fuel is not burning properly, and is cause for concern. Best that you do have the furnace checked ASAP. And be sure to ask all the question you need to understand what is going on.

I would also like to recommend a CO detector for your house. They are reasonable price and it can save your life.

Here's another ? For you guys. Radon gas is bad in our area. Could that gas be coming from the crawl space and cause these cracks? Our old furnace had a cracked heat exchanger. It was replaced and several years later that one cracked too. That was when we got the new one. Geeeeeeez I just don't know about these Lennox furnaces! Our first one was that "pulse-air" I think that's what it was called. The new one is just a regular lennox. Oh and I do have one of those detectors but it has never went off. It's probably junk too! LOL