Down Draft Dryer Room

Save electricity by line-drying your clothes.  This is often one of the first recommendations you find on energy savings websites, but there are a few snags in the implementation.   A line dryer in the backyard is fine if 1) you have a place to hang a line,  2) it is either sunny, dry, or warm enough to dry clothes and 3) you don’t mind the neighbors seeing your undies.   There is nothing worse than having your laundry get rained on, or having your sheets freeze into a stiff mess….

Hanging clothes up in the basement is not such a smart idea either in some climates, since the moisture will just add to the humidity in the house.  Not such a great idea if you live in one of the many areas of the world with high humidity.   I just spent the summer trying to figure out how to dehumidify my apartment to increase comfort!  Even in a dry climate, the regular drying of clothing in a room could cause some localized concentration of humidity,  trapped in a ceiling cavity.   Is there a way to design a ‘drying room’ space which can address these issues?

Many houses are now designed with ‘mud rooms.’  The irony is that this is where you hang up your wet clothes, yet these rooms are seldom designed with added ventilation. Why not a ‘drying room,’  or a ‘drying closet?’   One idea I had along these lines was to design vented shoe lockers which would have ductwork to connect it to the kitchen exhaust vent.  That way, any time the oven vent was turned on, the shoes would get dried.   My thought was that the events were sequential,  i.e.  I would likely be cooking after I was outside hiking, skiing, gardening.   And if not, I could still turn on the vent.  I’m not sure this is legal… but the shoe storage area was located directly under the pathway for the kitchen exhaust.

The other idea came from the down-draft solar food dehydrator, designed by Ray Wolf. This is the same principle as used in downdraft evaporative cooling, only the moisture is being introduced via wet clothing, or fruit.   Aside from Wolf’s now out of print book, there isn’t a lot of information available on the web –I’d be delighted if someone has a good resource, or plan, and can post a comment.

 

The concept is to capture heated air via an updraft solar heat collector and feed this hot air into the top of the dryer.  As the air collects moisture, it will sink.  The air then feeds into an intake at the bottom of the dryer, which leads to an exhaust chimney.  Thus the air is pulled through the cavity.     Barbara Kerr, one of the founders of the solar cooking movement , added  a heat transfer detail to help the vacuum action.   She attached a metal plate along the top third of the interior of the dehydrator,  on the wall which backed onto the exhaust chimney.   The incoming warm air would heat up the metal, which would then heat up the air in the exhaust chimney and cause a rising column.    Since all of this works best in an airtight cabinet, one of the posts suggested using an old fridge.  This could be fitted with an intake ductwork at the top, and an exhaust PVC chimney from the bottom.  If the top of this chimney were to be routed through the intake duct (keeping the air streams separate), it would preheat the exhaust.  That seems to be a great idea, especially since the ‘fridge’ already has shelving.

The next step is to take this concept to a drying room.This is essentially the same function as the very expensive laundry drying cabinets which have become so popular, only without the electric bill that comes from using these. In my house, I might have just the right space. I'm thinking of placing a solar collector outside the house, just over the old coal chute door, and feeding this hot dry air into the old coal storage room, which I can clean and seal up into a drying room. An outflow vent can be via another pipe, where the air flow is generated by a solar preheat at the exhaust end, to keep the pipe sucking out air. Stay tuned – it’s an idea worth cooking…