DIY kiln question for smart people (I'm disqualfd)

[Den Socling]

Time and temperature does affect color. On the good side, sapwood is often darkened and will blend in without being noticed. On the bad side, high temperature dulls and darkens.

I'm in the middle of an experiment to find the minimum temperature and time that it takes to color sapwood in Cherry and Red Oak. Hopefully, it's not necessary to dull the bright colors.

[logosoluser]

OK, I have a question or two concerning this issue with the AC for a kiln. Does the AC have to actually make cold air? I have an old unit that cools a little, but not enough to make it worth using in the house. I know the compressor still works on it, so I was wondering if thats all you needed anyway was the compressor taking the moisture out of the air. I am not very knowledge about anything along these lines, so I need real simple detailed information about this operation. I think it might be something that will work good for me.

[Buzz-sawyer]

Try the 6th post on this thread
It has to still be able to condense vapor....It HAS to cool,

[UrbanLogger]

The compressor takes moisture out of the air by compressing the coolant, which makes the coils cold which condenses moisture out of the air--no cold, no condensing.

[GaS]

Assuming the compressor is charged and operates correctly, perhaps the filter and/or fins need cleaned?   A friend of mine had an A/C he was gonna junk.  I said 'don't throw it out, l'll take it'...well it sat in his garage for a while till push came to shove and it was time to throw it out.  I said 'all I was gonna do is check the filter and coils'...sure enough, it had never been cleaned and the gentle waft of cool air became a blast of cold air.

Worth a shot on those old house units!

[Tn...Andy]

Hey Buzz-Sawyer....

Where ever did you find that article ?
I haven't seen it in years.......

andy

[Ironwood]

I did not read all the threads but heres my experience,. I know several people here in Pa that run large used commercial AC units to pull the moisture out of their kilns. They work very well. These folks monitor the kilns closely and have learned the details of wet bulb, dry bulb, and all the RH/ heat stuff (lots to keep track of). I bought a premade unit to avoid all the control/ monitoring issues they deal with. The DH kilns are simple in and of themselves to me it is the control units Nyle/ Ebac and the others provide that make it worth the money. It just depends on how much time you want to spend teaching yourself/ working out the bugs of your particular set up and then how closely do you want to monitor it. REID

[old3dogg]

I agree Reid.
All dry kilns are only as good as the people who operate them.

[woodhaven]

There is no such thing as (make cold air). What you have is air that the heat has been removed from.
You may say what is the differance. Well when trying to understand this stuff there is a BIG differance.

[4woody]

has any else made a kiln like this

[kelLOGg]

I've been following this thread for several weeks learning all I can. Now I am now putting together a tarp-covered rack in the 2nd floor of my barn for DH drying of small batches. I have a 1 year old window A/C unit we had to install in our home in an emergency last summer and now it is available for my wood drying efforts. The only problem is that I never saw condensate dripping from the unit. Is it possible that newly manufactured window units put the condensate into the warm exhaust to avoid dripping water?  If so, that would render the unit completely useless for wood drying. What were they thinking? Can anyone verify that some modern window units are dripless?

Concerning sizing of the operation - I want to dry 700 - 1000 BF from ~20% to ~7%. The unit I have is 125 VAC, 5.5 amps, 6000 BTUs/HR. Ignoring the dripless problem is this a reasonable size unit for the job?
Bob

[beenthere]

Can you tell us what the temperature is and what the RH is at that temperature (at which you are trying to get the water to condense off the AC unit) ?? 

[kelLOGg]

Here in piedmont NC the summers are 90+ degrees and 50+% RH daytime and nighttime lows are 70ish and up to 100% RH. All residential A/C and heat pump units I have ever seen in my area drip a steady stream of condensate.

Bob

[JimBuis]

There are cooling units that use the condensate to cool the condenser.  Whether or not that is your situation is hard to tell.  Irregardless, you'd need to have the condenser side of that A/C unit vented outside of the conditioned space, so it should not matter if there is condensate dripping or not.

Jim

[kelLOGg]

you'd need to have the condenser side of that A/C unit vented outside of the conditioned space, so it should not matter if there is condensate dripping or not.

If the condenser side (I assume that means the warm exhaust air) is vented outside I would have no heat added to the lumber, slowing the drying process. So if my unit uses the condensate to cool the condenser AND I want to use the waste heat for warming the lumber I cannot use it. Correct?

[PineNut]

Some of the window air conditioners have a slinger ring on the fan, which puts the condensate on the condenser. If you wanted to use one like this, you would have to find a way to drain the condensate and keep it away from the condenser coils.

[kelLOGg]

Aha! thanks, Pinenut - sounds like I can remove or disassemble something and get the condensate to drain instead of evaporate. Its worth a try.

[JimBuis]

If the condenser side (I assume that means the warm exhaust air) is vented outside I would have no heat added to the lumber, slowing the drying process. So if my unit uses the condensate to cool the condenser AND I want to use the waste heat for warming the lumber I cannot use it. Correct?

I am not totally clear on what you are doing, but here goes.  If you simply stick a window A/C unit in a room plug it in and drain the condensate out of the room, you will succeed in lowering the moisture content of the room, but the temperature of the room will not increase significantly.  The reason being you are dumping almost as much cool air into the space as warm air.  The small temperature increase will result from the heat put off by the compressor and fan motor.

To make this work with any hope of efficiency, you'd have to duct the cold air outside the room while still sucking in air from the room to remove the moisture.  Anyway, it sounds like you are wanting to use a window A/C unit in place of a dehumidifier.  I've never tried it, but I doubt it would work very well.

IMHO,
Jim

[kelLOGg]

I plan to duct the cold air out of the kiln via metal ducting to help warm it up to ambient temp and duct it back to the kiln as makeup air. I chose an AC unit because I have one and earlier posts in this thread cite usage of AC units for DH drying.