Doors and Windows - Wet (dripping) windows

Just purchase an older house. Currently vacant. Heat set around 50 in main portion, 40 in those with no plumbing. Gas baseboard heat. Outside temp around 18 degrees

Windows have wood frames, storm windows have metal frames.

Condensation would be to little a word to describe this condition, windows are dripping. I did notice prior to purchase that the window sills looked as thought they had gotten wet, I thought maybe they'd been left open in the rain??

Little to no caulk on exterior (I checked this a.m.)

I was told that perhaps a dirty chimney would cause this in a gas heated house..

Where do I start?

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***Moderator's note: Duplicate thread created in Fireplaces and Chimneys topic has been deleted***

To much humidity and not enough ventilation would be my first guess! buy a cheap Humidity meter to find out what the RH is inside home.