wrote:

We live in a rented townhouse. During the winter when the heat is
used, the place really gets dry. So much so that it dries out the
sinus and causes discomfort. Is there any easy practical way to
humidify this place?

Sure. Caulk it. Andersen says an average family of 4 evaporate 2 gallons
of water per day, ie 0.0116 pounds per minute... 70 F air weighs about
0.075 lb/ft^3, so you can raise the RH from wo = 0.0025 pounds of water
per pound of dry air outdoors to wi = 0.0047 indoors (70 F at 30% RH) by
reducing the air leaks until 0.075C(wi-wo) = 0.0116 pounds of water per
minute, ie C = 70 cfm. This will also reduce your heating bill.

Nick