A Dryer for Moister Air

One of the least “Green” appliances ever created is the clothes dryer. It does the same job as hanging clothes out on a line, but consumes a lot of energy. I’ll forgo the rant about zoning laws that even prohibit hanging out the wash, and tell you about a slightly greener way to live with one, at least during the cold months when you really don’t want to go outside to hang the wash.

Bag plugged dryer duct

In the winter, I pull the duct from the dryer to the wall vent and plug the outside vent with a grocery bag stuffed with rumpled grocery bags (seen at the top). The outer bag only lasts one season, but meanwhile has a more virtuous life as an energy saving insulator. Surely the whole stuffed bag saves more oil than was used to originally produce the bags that had already been used for their original purpose.

Dryer Setup But the real money is that the pipe rising from the dryer goes into a filter box. Shown here is my temporary prototype that I made from salvaged cardboard as a first try about fifteen years ago (and still in use today). I used a 20″ square filter because I had those sitting around from the use described in my post Fantastic Filter Idea.

You see, like any appliance, the dryer converts electricity into heat. It heats up already-warm house air to pull the moisture from the clothes, and then dumps it outside! It pumps warm air outside! And we pay to heat it even more in the process. So I figure that we may as well heat and humidify the air in the house during the months where that is desirable.

As to the filters: A dryer pummels your clothes to soften them as a substitute for letting them waft in a breeze. This abuse tears loose many small fibers; dust. Sure, the dryer has a lint trap. But anyone who has looked at their dryer exhaust duct knows that some fraction of the lint gets through.

Prototype filter boxSo my filter box holds a cheap, blue, loose-weave filter that slides in through a slot on the side. This filter can be taken out and beaten clean outside every month or so. After a couple of years, I realized how much of even smaller dust was still getting through. So I first set up the hanging fan shown in Fantastic Filter Idea , and then chose to add a pleated filter to the prototype. The inner filter gets most of the lint, and the outer one catches most of what is left. The separate one on the ceiling catches still more. My tools across the room no longer get so dusty. Nor do my lungs.

The whole house then benefits from the heat and humidity that wafts up the basement stairwell, because warm air rises, and the ceiling-mounted box fan pushes the air toward the stairs.

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2 Responses to “A Dryer for Moister Air”


  1. 1 Wade February 19, 2013 at 3:08 pm

    I’ve dealt with this topic on my own, so here are some thoughts. First off, there isn’t really an energy advantage to this method of winter clothes drying over drying your clothes on an indoor line, which is what I do. That is, heat or no, all the moisture stays in your house either way. While the heat from the dryer is nice, it (probably) has a larger carbon footprint than the gas-generated heat from your radiator system, which you are essentially displacing (complicated analysis with a radiant system, arguments about fracking, etc). My personal experience suggests that the lint you find in the dryer is generated as much in the washing process as in the drying process (I think I get a lot of lint in my apartment that comes off my line dried clothes). I’d say line dry, then air fluff in the dryer with your filter system for maximizing your energy savings.

    • 2 Dan Klarmann February 19, 2013 at 5:13 pm

      One problem with line drying inside is the lack of breezes to soften the clothes and send away the lint. When we hang to dry indoors, we do tumble those items on fluff for a while.

      Certainly, electric BTU’s are less efficient than methane ones in terms of total energy cycle. But even with new high efficiency methane furnaces, some heat goes up the flue. Electric heat is entirely delivered, every kilowatt-hour puts 3,413 BTU’s into the house, whether from a non-vented dryer, a light, a router, or a television.

      But electric BTU’s (as watts) currently cost less than gas BTU’s (as therms) per energy unit delivered to the house! (Unintended pun).
      We really need to monetize carbon waste to fix that! Whatever became of cap-and-trade?


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