Plumb Dangerous Thinkin

[Fla._Deadheader]

Eggzacktly, how does a de-humidifier work???

 If ya got an old air conditioner, and it doesn't get cold, will it still take moisture out of the air???  If it will blow warm air, instead of cold, why would it not dry wood, in a tightly closed environment???

[Tom]

I canT talk like a book but here goes........

Warm air holds more water than cold air
Cold air gives up water the colder it gets

A tightly enclosed space has no way of getting rid of the water even if you get it out of the wood.

So, Here's kinda what you do.
Heat the wood and the air so that the air can become saturated with water.

Take the saturated air to another place and cool it.  The cool air will drop the water.

Get rid of the water and send the dry air back in there where the wood is to be warmed back up so it can carry the water out again.  (A DH might work in an enclosed area if you can get rid of the water.)

A stack of wood is hard to get the water out of because it's hard to move the air inside of the stack.  You have to get rid of that water-saturated air from inside of the stack.  That's why you stack wood in fairly narrow stacks in the open or move the air with fans in a kiln.

Now somebody that really knows will come along and give you some formulas

[Fla._Deadheader]

  By tightly closed, I MEANT set the A/C up, as you would a de-humdinger. Ain't they about the same thing??? A de-humdinger don't have cold air, right

[tawilson]

Sounds like your old air conditioner is broke. So no cooling or dehumification. A dehumidifier cools and heats the air to get the moisture out and send it out at the same temp. So a functioning air conditioner could work.

[woodhaven]

Tom,
You did a right good job at that. I would never have gotten that far down to earth.

FD,
Be a little more specific and I will give it a shot.

Here is a couple of things to consider.
Water boils at 212 Degrees
The Refrigerant in a window unit boils at -20 degrees
Technically speaking cold is -460 degrees
There is still heat in the air down to -459 degrees

You are right in the fact that a dehumidifier or air conditioner doesn't have cold air.
It does have air that the heat has been removed from. It may seem the same but there is a big differance.

[Fla._Deadheader]

 I just got back from a visit with Ole Jeeves. He says that there IS a cold coil in a de-humdinger, that condenses the water from the air Guess my idea wasn't so dangerous after all

[woodhaven]

You are zactly right. The cold coil is the evaperator and containes the refrigerant with the -20 degree boiling point.
That is exactly the same coil that is in front of a window unit.
The one that sweats. If you had -20 degree blood in your body you would sweat at a low temp too.

[Fla._Deadheader]

Then, can ya reverse the fan on a A/C and get a BIG de-humdinger

[woodhaven]

Nope
Try again

[Ianab]

Okies...
I'll have a go at explaining how it works
Here's my simple DH unit with the covers taken off  



The components in a DH and an airconditioner are basically similar, but the air flows thru the DH in one path. In an Aircon you have your inside air thru one radiator, and the outside air thru the other one.
Does that make sense  

Ian

[tawilson]

A picture is worth a thousand words.

[woodhaven]

FD,
Got any questions about Ianab's picture? It's perfect. There is one missing component which wouldn't mean much to you at this point.
If you stuck a fan between his two coils and had the air blowing forward out of the cold coil you would have turned it back into a AC unit.

[Fla._Deadheader]

  I think I's got it !!!!!!!!!!!!!!!!

[LeeB]

So if you reverse the fan in an a.c. you get a dehumidifier? LeeB

[woodhaven]

Nope, Not at all.
If you reversed the fan what you would get is little to no air flow.
The fan blade pitch is directional. Changing that would do nothing.

[Don_Lewis]

There is a difference in the pressures of the two coils. In a DH kiln, depending in the refrigerant, the fluid is boiling off at about 40 PSIG. In order to boil anything, water or refrigerant you have to add heat. In a boiler, the heat comes from the fire. In a DH unit, the heat comes from the air. This causes the air to be cooled and when cool enough, the water in the air condenses. Then the refrigerant pressure is raised by the compressor to about 300 PSIG, the condenser does just what a steam coil does, condenses the gas to a liquid giving up heat to the air. The heat given up is the total of the heat removed by the evaporator plus the energy put in at the compressor. You have all had the experience of using a spray can and haing it get cold as you spray. That is the refrigerant boiling off just like in an evaporator. If that refrigerant could be collected at the spray nozzle, and pumped up and put back in the can, you would have a refrigeration system and the sweating on the side of the can would be dehumdification.

[woodhaven]

Don is also right.
If you could take a glass of refrigerant and pour it out it would disapear before it ever hit the floor. Back before ozone became such a big issure I could do all kinds of things with refrigerant. Not anymore nowdays you can go to jail for stuff I did. Anytime I had a part that needed to be shrinked to fit I just spray some Freon on it. A lot quicked than leaving it in the freezer overnight. If any of you have ever changed piston sleeves in a engine you know what I mean.

[rs1626]

so if you unhook the fan in the a/c unit and connect a fan to
the front of the unit will it work to dry lumber?

[Buzz-sawyer]

simple question ;
simple answer;
put old inefficient ac window unit on a table in the middle of a closed room, and it will both heat, and dehumidify at the same time
answer, YES

[tawilson]

That's if it is still functional. Fla_Deadheader started out by saying he had "an old air conditioner, and it doesn't get cold", so I took that to mean it was broke, so no cooling or dehumidifying.