Dry Air Please Help

Whatever goes into the return

has to go to the supply and hence the space at some point....

Just because there is some recirculation around the return and back to the fan, probably 90% goes to the space with each pass. You could never have a molecule entirely dedicated to rat-racing the return while dry air ignores the show.

Moisture will migrate wherever it is not.

If you evaporated a cup of water in a dry room or the Astrodome, each molecule would be dispersed equidistantly from each other.

Moisture molecules in suspension behave like some engineers I know; holding a glass of club soda, wearing stained ties and weeping pocket liners at a cocktail party, these molecules will seek their own space and stay there, stairing at their shoes, until more engineers enter the room. Then they move around a bit more. As Bruce Stevens once pointed out to me, if they are extroverted, they stare at your shoes.

~8^)>

If you use your wood stove with any regularity, there was a neat steamer in iron or bronze, in the shape of a dragon. Steam would emit from the nostrils and thrill small children. Playing "Pat the Dragon" (pat being a verb not a proper noun -I think) is a very short game, so be warned...

I always have liked

Aprilaire products. Keep in mind a humidifier like that needs its own maintenence plan of attack, learn about the one you buy, keep some spare pads, etc. as any aggresive water will eat these things quickly. And Brad, as far as engineers are concerned, you need to get out more! Come to the D.C. area sometime and play with us, and see how real working engineers behave! BTW, I'm looking at having new sidestream centrifugal separators installed on my condenser water systems, do you use them, and if so what make? I'm looking at Lakos.

Just a homeowner who also had lots of trouble with lack of an ability to create enough humidity due to oversized equipment, so I've learned a bit over time.

Flow through humidifiers of any brand won't work all that great with room temperature recirculated air. It doesn't matter if you use one with a bypass duct or fan powered (all the major brands such as Aprilaire, Skuttle, General Filters, ... have both styles of flow through). Of course you will get some evaporation, but a higher percentage of the input water will flow down the drain. At 3 to 3.5 gallons per hour you go through a lot of water and not produce much water vapor. Aprilaire has the model 350/360 designed to operate independent of an air handler. It is suppose to be setup plumbed to a hot water source. It's spec says it will produce 0.5 gal/hr of water vapor, but it consumes 6 gal/hr of 140F water. Given that spec, you can imagine the relatively minimal performance you'd get with a standard flow-through unit using cold water at the more modest 3 - 3.5 gallon per hour rate (I'd guess running one 24x7 you might generate 1 or 2 gallons per day).

Although they may be expensive to operate depending on your electric rates, the various steam units (Skuttle, Honeywell, EWC) will give you the best performance and can operate the AHer fan without a call for heat. The ultimate are Nortec steam humidifiers which create the steam in a disposable container. When it fills with all the hardness mineral ick, you just replace it with another bottle.