drying questions

xlogger · February 28, 2016, 06:26:06 PM

It time to get away from my construction topic and make a new topic. I've not pulled any water out of my first load in a few days now. Remember I have 8/4 slabs in there. At 3/4" deep with my pinless meter they are showing on the walnut about 10% and the maple in the 8% range. I was hoping to get to 7-8% on both then turn the heat up above 135°. Should I leave them in awhile longer or maybe go ahead and cut up the heat to finish them off. If I leave them in longer since I'm not getting any water could you just leave the heat and fans on and cut off the compressor. By the way the DB has been around 140 and the WB was showing 78 tonight.

samandothers · February 28, 2016, 06:29:34 PM

Look forward to this thread and feedback as much as the construction thread. Nice to have your first load so close!

bkaimwood · February 28, 2016, 07:29:06 PM

I'd run the heat up...but I play with dice often...

WDH · February 28, 2016, 09:01:14 PM

Sounds like that the compressor has tripped. The high temp shut-off on the refrigerant line on my L53 trips at 133 degrees if the compressor is running

. If you take the side panel off, you will see a re-set button on the refrigerant line. That could be why your are not getting any water.

WDH · February 28, 2016, 09:31:20 PM

I found out about the compressor tripping on the L53 the hard way. After running the kiln initially for a few days, I was not getting any water and suspected that the compressor was not functioning even though the display showed the compressor as "on". I called Nyle and we discussed several things. They said to shut the unit down for a few hours try it again. I did, no luck. Then shut it down for a day, and tried again. No water. I was frustrated and did not know what to do. Was considering sending the unit back to Nyle. Thinking that there might be a loose wire or something, I opened the side panel. All the wires looked fine. I noticed this little button. I think that it was green. So I pressed the button. No click or anything, the button just went in when I pressed it and came back out. Not knowing what to do and despondent, I put the cover back on, started the unit back up hoping for a miracle. Nothing. Sat there pondering how I was going to uninstall the unit after all the very hard work to get it installed in the chamber. About five minutes went by when I heard the compressor kick on. After a few minutes, there was water in the bucket. Perplexed, I called Nyle and told the Tech what I had done and what happened. The Tech said, oh, I forgot to tell you that the compressor will trip if the temp gets much over 130 degrees on the DB. I told him about pushing the green button, but nothing happened until about five minutes when the compressor kicked on. The Tech said, oh, I forgot to tell you that there is a 5 minute delay when the kiln reaches 80 degrees on the DB and the compressor gets the signal to come on. So, I learned some things.

1). None of this is in the manual except for the 2 degree safety margin
2). When drying wood, keep the DB temp below 125 degrees
3). The compressor will trip somewhere over about 133 degrees and will have to be re-set.
4). There is a two degree lag for when the compressor should come on so that the unit does not cycle on and off when the temperature set points are reached. For example, it the WB is set at 75 degrees, then the compressor will not come on until the WB temp reaches 77 degrees as a safety margin.
5). Once a set point has been reached, there is a 5 minute delay from when the set point temperature is reached and when the compressor will kick on.
6). Even though the display might show the compressor as "on", that just means that the temperatures are in the right range for it to be running, does not mean that it is actually running, i.e. like when it has tripped due to high temperatures.
7). The heater and the compressor might both show "on" on the dipslay, but there is not enough amps from the 110 circuit to run both the compressor and the heater at the same time. When the temps are right for the compressor to run, and the heater is on to heat the kiln, when the compressor kicks on, the heater will shut off.

xlogger · February 29, 2016, 06:26:59 AM

Thanks Danny, I'll take off the side and press the button this morning. But I'm pretty sure it not been over 122° since I've been running it. Most of the time it's just under 120°. After about a week now of having this wood in there, I've only got about 2 gallons of water out total, but the first night it did run out on the floor because I didn't have the drain hose tight.

GeneWengert-WoodDoc · February 29, 2016, 07:11:26 AM

It sounds like that in this case, A pinless meter is not going to give you very accurate MCs. The meter needs a correction for density of the wood. If your wood is slightly denser than normal, it will read higher in MC than it really is. Likewise, some Pinless meters are calibrated for 1" and so with thicker will give a higher reading than the truth. So, my guess is that you already have dry wood. Also note that unless the air is under 30% RH, you will not get any drying, and when under 30% RH some DH units will not work as the cold coils will freeze, so the compressor stops working at low RH values to protect itself.

Maybe you can borrow a pin meter for a quick test.

WDH · February 29, 2016, 07:16:35 AM

Using the pinless meter, I have noticed that the moisture content can vary a couple of % on the same board depending on where you place the meter. I assume this is because the density changes as you move from the juvenile pith wood to the mature outside wood.

GeneWengert-WoodDoc · February 29, 2016, 07:25:15 AM

I have seen a Pinless get one reading on one face and a different reading at the same location but on the other side of,the lumber...with 1" or 2" stock.

YellowHammer · February 29, 2016, 10:27:56 PM

Here is the high pressure reset switch.

I would recommend that you invest in a Delhmorst pin meter with the remote slide hammer and insulated pins. It will let you know what the moisture level is of even thick slabs. It ain't cheap but you can trust it.

Glad to hear everything is up running

xlogger · March 01, 2016, 05:05:51 AM

After reading Danny's answer I did what he suggested and the compressor does work, we believe that the wood is just as dry as it will get. So I cut the heat up threw the night to take it out today. Will let you know tonight how it did.
I've got some air dried cherry, 8/4 and 4/4 that I going to put in next. Both are in the mid teens on mc.

xlogger · March 01, 2016, 08:36:30 PM

I got the first load out today. The walnut looks good but several of the maple slabs where not flat. I had this trouble on the last maple slabs I cut and dried in solar kiln. How does 8/4 wide maple do you some of you?

GeneWengert-WoodDoc · March 01, 2016, 10:50:26 PM

How close is the lumber to the center of the log? The closer, the more natural cup.

xlogger · March 02, 2016, 06:06:25 AM

Yes most of the worst ones was near the pith. I'm thinking on next large maple that I'll cut out about 4-5" with pith in center and then cut 4/4 boards out of that piece kind of like you quarter saw them.

Den Socling · March 02, 2016, 09:32:15 AM

This made me think about this picture.

xlogger · March 04, 2016, 06:23:59 AM

Just an easy question for you. Remember I'm in a learning process here. If the wet bulb is set at 75° like you have told me to set and the compressor is running all the time, is the higher the wet bulb temp the less time compressor is running? How much time is it running like at 90°? I'm just looking at the drying schedules on group 2 woods and it shows starting out at a wet bulb over 45% mc at 85° and finishing it off when under 25% mc to a wb at 90°.

WDH · March 04, 2016, 07:27:20 PM

The compressor only runs when the wet bulb temp is at or above the set point. If you set the WB at 95 degrees, the compressor will not start up until the temp reaches 97 degrees (2 degree delay), and will only run as long as the wet bulb temp stays above 95 degrees.

If you set air dried wood below 20% moisture content with a wet bulb of 75 degrees, then the compressor will run 100% of the time, removing the maximum amount of water, which is what you want with air dried wood.

If the wood is green, the according to the species chart, you have to set the WB higher so that the compressor only runs when the wet bulb temp is exceeded. This keeps higher humidity in the kiln with the wet wood so that you do not dry it too fast. The smaller the difference between the dry bulb and the wet bulb, the higher the humidity, and the gentler the drying. When the wood gets below about 20 - 25%, you can dry it wide open, so that is when you set the WB low like at 75 degrees to assure that the compressor will run full out.

bkaimwood · March 04, 2016, 07:44:19 PM

Don't sweat the maple, xlogger... I recently had 8 or 9 logs worth of slabs in the kiln, got 3 logs out with defect... All were maple, all slabs were close to, or included the pith, so I learned too... I used to put stuff with the pith in it at the lower part of the stack, thinking the weight would minimize loss...wrong. It just defects everything above it...now I saw it out, or put them at the top, knowing I will make shorts from defect slabs, or the will be ripped and reglue to eliminate the pith defect... Both get you something back from your investment, and it pays more than 4/4 right now... Last note, I've been burned by walnut holding moisturer, it can be tough in the end... Skip up 10 degrees or more fixes it...congratulations on your overall success!!