Kiln drying?

[WoodChucker]

I just finished drying my first load of red pine using my new kiln and the Nyle L-50 deh unit. It went well, and the lumber turned out just find. Only problem was after drying I could only get the temp to go up to 140 deg to set the pitch, it just wouldn't go up to the target temp of 160 deg. I think I can correct this and get the temp up a little higher by making a couple of insulated covers for the two vents and sealing the outside of the doors somehow when trying set pitch. All in all I'm very happy with it and if my next load of red oak turns out as good as the pine did, then I'll be very very happy.  8)

Now to my question. The book said to set the percentage timer to 100% and the temp to 120 deg. After the the third day the temp went up to 128 deg so I did what the book said and open the vents (2) and the temp came back down. I ended up leaving one vent open (full) and the other one just cracked a little to keep the temp stable at 120 deg for the rest of the drying cycle.

Now, would it not be better to adjust the percentage timer or temp setting, rather then the vents to get the temp right? Wouldn't leaving the vents open allow outside humidity inside the drying chamber and just over work the deh? Or if not actually over working the unit, removing moisture that wouldn't be there with the vents closed?  I know the book said that the vents being open had an effect on MC but I don't remember it saying if one way was better then the other. I will re-read the book, but just wanted your advice and opinions? Thanks!


R.T.

[Don_Lewis]

Actually you are better off venting. Even if it were raining outside, when the air comes into the kiln and is heated to 120, the relative humidity and EMC drop to below what you need. The fact that you need venting is proof the chamber is tight and well insulated. It takes quite a lot of heat to get the kiln up to 160 and the heater in an L50 is not large because it has to fit on a 120v system. Your pitch is now set for 140 and the wood would have to go over 140 for it to soften again. In most cases you are fine.

[WoodChucker]

Thanks Don, once again I really appreciate the help!

While I have your attention, can you tell how that little temperature sensor should be connected to the wall bracket on the L-50? Does it clamp around the metal part or should it be clamped around the black plastic at the end? It seemed a little tight when trying to get it around the plastic, so I just clamped it around the metal and have it pointing up at about a 45 deg angle, is that OK?  Thanks!

R.T.  

[Don_Lewis]

The temperature sensing part is right at the very tip if the sensor so as long as that part is not touching anything and has good air flow over it, you are fine

[WoodChucker]

Ok, thanks Don!

R.T.