zlacker

Even so, it does not explain why one method of heating the air would feel different than another, unless there is something physically different in their effects.

Radiant heat feels somewhat different than warm air, but if radiant heat from the radiators of a steam or water system is significant, would that not make them feel dryer? Our house has water radiators, and I do not notice the radiant heat from them.

I believe Retric's explanation is the correct one, given that human activity tends to increase the absolute humidity of interior air.