Kiln Capacity

[YellowHammer]

Is there a way to test the water removal capacity of a kiln unit? I have a new small dehumidifier kiln and want to run a calibration test to see if it meets manufacturer specs of lbs of water removed per day. How would such a test be run on site? 
Thanks,
YellowHammer

[scsmith42]

Put in a green load and set it so that the compressor is running flat out, and capture the amount of water that it removes in a specified amount of time and then do the math.  Give the kiln time to get up to temperature and for the water to start flowing.

Water weighs around 7 lbs (oops - that is diesel fuel) 8.34 lbs per gallon.

[FeltzE]

If your using a dehumidification unit. Place a bucket under the discharge tube (outside the kiln) and measure the amount of water captured over a known period of time.

Kiln should be up to temp, the compresser running at 100% of the hour, the kiln charge should be up to temperature and preferablly green stock.

Keep in mind that different wood must be dried at different rates to reduce the chance of checking. Pine and poplar are very forgiving, run it hot and fast. Oak on the other hand must not dry at more than 3% / day or you will blow your load and have great kindling.

Good luck

[YellowHammer]

I tried the bucket method and it showed the amount of water came out at less than half the advertised capacity, at a rate about 1.5 MC  loss per day, max.  This was the first load of mixed oak, the wood went in at at 35 percent MC, somewhat air dried, and I ran the temp up to 115 F for several days to hold a consistent EMC of 6 perent.  The kiln water removal rate consistently came in significantly low, but I'm not convinced its the kiln's fault as its new, the reputation of the company is excellent, and I willing to admit it may be my fault since I'm new to this DH kiln. 

So now that load of wood is dry, and my kiln is empty, waiting on the next load.  So before I put it in, I was hoping for a technique to test the capacity because once its in, I won't want to take it out until its completed it's cycle, several weeks from now. 

Has anybody tested their kiln to see if it meets specs?  Should the bucket method work at the conditions I was running?  Since the kiln can only remove water that's in the air from the wood, is there a way to saturate the air in the kiln to test the true water removal capacity? What about buckets of water in the kiln warmed up and running 100 percent compressor?

Thanks,
YH

[scsmith42]

The thing that I have seen is that different woods give up their moisture at different rates.  Wood that has been air dried does not seem to kiln dry as fast as green wood.

Pine is relatively fast and easy, so if you want to measure the volume then fill your kiln up with some 8/4 green pine and check the rate.

[Den Socling]

A load of air dried Oak would not indicate the dehumidifying capacity, for sure. As Scott says, use green Pine if you really want to Know.

[FeltzE]

I don't think I'd want to try to test my kiln on oak, as the maximum mc reduction daily in 4/4 lumber shouldn't exceed 3%.  Run some green 4/4 Pine or Poplar and test that at 100% cycle and 120degrees kiln temp.


To measure the relative humidity you will need some additional equipment not included with your kiln controls. a RH meter or wet bulb and dry bulb measurements.

[Woodey]

I'm drying my first load of mixed oak 2500 bf. I know now that was not the best choice for my test load.
The chamber has a Nyle L200 unit that I purchased last year. It is a 2003 year model that was never hooked up. The wood is showing 10% to 16% moisture. Wood was air dried some before being put in the kiln.

I have the units heat set on 110 degree and temp is showing 120 in the chamber. Compressor is running 45 min. on the hour.
I measured 3 1/2 pints in one hour and 3 1/4 pints the next hour. I thought it would pull more water per hour. What can I do to get more water per hour cycle?

Also I have purchased 2 different  RH meter. The wireless would flash 1-99 the 99-1, then I put one in the chamber and it went out.
What types of RH meter would you suggest other than the wet/dry bulb thermometer.

Thanks for your post YellowHammer, I was also wonder the same question on water removal.

[FeltzE]

With the L200 2500 ft of oak at 16% I'd runn at 100% compressor and try to hold the temp at 120, vent if you need to.

You won't get a maximum flow of water as you don't have that much in the oak and it's not going to release it fast.

Run the kiln untill your water drip drops off to less than 5 gal in 24 hrs then hold everything for another 24 hrs. when you shut down you can keep the lumber in the hot kiln and allow more water to "equalize" in the wood as well for 24 hrs.

That certainly isn't the technical solution but it should work

[FeltzE]

oh, btw electronic stuff not designed for a kiln don't seem to like the hot and humid conditions of the kiln life