I started two threads about humidification and heat recovery over the weekend. Thanks to everyone who posted, agreeing with me or not. There's one thing I didn't think about and that's regional differences. I wouldn't be boiling water or venting a dryer indoors any time of year in Hawaii and I certainly don't do it in NY when it's warm outside. Regional and climatic differences are important. Forget about everything I said if you live someplace where you can heat your home with a heat pump. That may be possible a hundred years from now where I live, but the beaches will be a few yards south of the Long Island Expressway. I'm glad I won't be here to see that.