Everything may be fine with my system, but it seems that it is taking a very long time for the home to heat up, which results in the furnace running all the time.

The natural gas furnace is struggling to even get to the 68 degrees the thermostat is set to, and the temperature is only in the 30s or 40's outside. And it takes hours for the temperature to rise as little as on degree.

The furnace is hot, but very little air is leaving the vents. I can turn the fan from "auto" to "on" on the thermostat and I can hear it kick on (the furnace is already running without turning this fan on) and can feel more air coming out of the vents, but it still seems slow and I have to manually control the switch.

The house is sealed up pretty good, unused rooms have the doors and vents closed, so I don't think the issue is that furnace can't keep up with the heat loss, though I could be wrong. The house seems to lose about 1-2 degrees and hour in 30/40 degrees outdoor temps.

We just bought this home, so I don't really know the characteristics of the system.

Would suggest a furnace check up to see why it's not performing properly. Need to get this done before it really gets cold and below zero!

Without knowing if this is the norm, the possibilities are many, ranging from something configured wrong in the tstat all the way on up to a furnace that is too small for the house.

You're going to need someone to come in and run through all these possibilities.

As a rough check, how big is the house sq ft and what size furnace do you have?

Thanks for the responses.

I don't really have a lot of info to add. The house is about 1500 sq. ft. I don't know how big the furnace is other than it's about the size of an NFL lineman.

Mostly, I just want some confirmation that I am not crazy that something might be wrong.

And if the solution is an obvious one, I would like to know that too.

Check the furnace filter?

Remember you cannot close to many of the air vents. The furnace will stop heating or overheat causing the high limit to trip. The furnace is designed to heat the entire house and people trying to conserve energy think they can close off a bunch of vents and they will save money. The furnace system is not designed to have to many vents closed.

Also check to make sure the cold air return is not blocked off.