zlacker

A lot of EU heats by steam/water radiators. These don't dry the air the same way forced air heating does.

You are right about absolute/relative humidity, but our basement feels damper in winter than summer.

>>mellav+(OP)
Forced air and radiators dry the air equally. Steam radiators sometimes can add humidity to the air it is limited and only when they are initially heating up before the valve closes. What causes dry air in the winter is the act of heating air up. Relative humidity is based on the temperature of the air, so if there is a fixed amount of water in the air, as you heat it the relative humidity goes down. So in the winter cold air slowly comes into the house via air leakage. This air is heated up which drops its relative humidity down. I have lived in houses with baseboard heat and with forced air, and recently converted my house from baseboard heat to forced air. There is no real difference in the relative humidity in the house.

>>sbradf+F2
The way I understand this at the gut, conversational level, is by noticing that hot air can carry more water, therefore it will dry your skin faster, which is what "feels" like the air being dry.

Heating doesn't remove water from the air, as you explained. But that's what people assume when they argue that "heating doesn't dry the air" as I've heard in the past. Using relative humidity is a good explanation.

>>sbradf+F2
Forced Air generally increase the exchange of new air from outside. Individual rooms will tend to be above or below ambient pressure which causes an exchange of air with the outside. Carefully balanced systems can minimize the effect, but homes are rarely built with this in mind.

You can get a related effect with thermostats which raise and lower the house’s temperature over the day as air expands with increased temperature.

>>ihavea+94
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.

>>mellav+(OP)
Steam radiators absolutely dry out the air.

>>Retric+N4
That is definitely an issue that is out there. Sadly cheap builders try and get away with a single return per floor in a house which is simply not enough. My point is mostly that forced air versus hydronic isn't what causes a difference in dryness of air. It largely comes down to the quality of the install of each and the tightness of the home. Hydronic is typically more expensive and tends to be found it better built homes. My house is an exception to that rule though, I am still working on sealing up air leaks from where all the pipes ran for our baseboard heat.