Moisture meters and kiln dried wood

[Logburner]

Hi all you knowledgeable guys!

 

I thought I knew quite a bit about firewood  -  I buy lots of it for a large wood boiler which basically heats my whole house.

 

But now I have got really confused!

 

I bought some kiln dried ash and discovered it burned with considerable difficulty, heating my wood- boiler combustion chamber up to 350 degrees at best, when it normally burns at between 600 and 700 degrees.

 

I have never bought kiln dried before but after all that is said about it on various websites you would have thought you could trust that process completely (at least I thought so).   All the same, I became, well, a little bit suspicious after getting back to the supplier, who at this point was uncooperative.

 

I started wondering if the wood was still wet inside  -  it certainly felt rather heavy.

 

So I used a newly purchased ExTech moisture meter, and on the outside of the logs, using the pin method, it was registering 12 - 15%, but when I used the scanning method it registered 30 - 35%.  That measurement, as I understand it, takes account of moisture up to 1" deep.  I knew I needed to split the wood to check properly, and this I did.  This time, testing several split logs, I found that the inside was consistently around 22% using the pin method, but using the scanning method the moisture meter almost took off, bleeping like fury, with three water droplets displayed, and gave readings of 50 to 70%, shifting a bit as I moved it around because of needing a flat surface.

 

All this raises many questions in my mind  -  about the  faith one should have in kiln drying, as well as the strange differences in the moisture readings (I set it correctly each time for either the pin method or the scanning method) and I got results (as above) that I find incomprehensible.

 

Not least,  what I do with a cellar full of tightly stacked kiln-dried (probably wet) wood that came down via a shute and cannot easily be got out and a supplier who's not interested to know what the problem is.

 

Any answers you can give to any part of this query would be so much appreciated.

 

Cheers all!  Have a nice day!

 

 

 

 

[Woodworks]

Dry ash should burn very well.

 

Kiln dried is no guarantee of quality dry wood it's just a means of lowering moisture content in wood. Did they specify a moisture content it was dried to? 

 

Not familiar with a scanning moisture meter as I have only used the pin type but on the whole pin type are relatively accurate from reports on here. The only perfect way you test moisture content would be to oven dry a few samples. https://www.forestresearch.gov.uk/documents/1979/FR_BEC_Testing_Moisture_Content_Simple_method_2011.pdf

[topchippyles]

1 hour ago, Logburner said:

Hi all you knowledgeable guys!

 

I thought I knew quite a bit about firewood  -  I buy lots of it for a large wood boiler which basically heats my whole house.

 

But now I have got really confused!

 

I bought some kiln dried ash and discovered it burned with considerable difficulty, heating my wood- boiler combustion chamber up to 350 degrees at best, when it normally burns at between 600 and 700 degrees.

 

I have never bought kiln dried before but after all that is said about it on various websites you would have thought you could trust that process completely (at least I thought so).   All the same, I became, well, a little bit suspicious after getting back to the supplier, who at this point was uncooperative.

 

I started wondering if the wood was still wet inside  -  it certainly felt rather heavy.

 

So I used a newly purchased ExTech moisture meter, and on the outside of the logs, using the pin method, it was registering 12 - 15%, but when I used the scanning method it registered 30 - 35%.  That measurement, as I understand it, takes account of moisture up to 1" deep.  I knew I needed to split the wood to check properly, and this I did.  This time, testing several split logs, I found that the inside was consistently around 22% using the pin method, but using the scanning method the moisture meter almost took off, bleeping like fury, with three water droplets displayed, and gave readings of 50 to 70%, shifting a bit as I moved it around because of needing a flat surface.

 

All this raises many questions in my mind  -  about the  faith one should have in kiln drying, as well as the strange differences in the moisture readings (I set it correctly each time for either the pin method or the scanning method) and I got results (as above) that I find incomprehensible.

 

Not least,  what I do with a cellar full of tightly stacked kiln-dried (probably wet) wood that came down via a shute and cannot easily be got out and a supplier who's not interested to know what the problem is.

 

Any answers you can give to any part of this query would be so much appreciated.

 

Cheers all!  Have a nice day!

 

 

 

 

Ash makes great firewood and burns brilliant so wood is not the issue but the moisture content. Kiln drying is a proven system used world wide so can rule that out being the cause. Supplier is the problem here without doubt so i would be taking this up with them. Is not been left to dry long enough in the ovens and most likely demand out stripping supply with the shortage of imported timber (brexit) Can you mix it in with some other drier timber say 50/50 and see if it brings the temp up

Edited March 4, 2021 by topchippyles

[Dan Maynard]

And just to add, whether it's been briefly in a kiln or not I'm afraid the bottom line is that it's wet and isn't going to dry well tightly stacked in a cellar.

Only options I can see are to take the wood out and stack it where the wind can blow round it over the summer, or else turn your cellar into a kiln with dehumidifiers and fans (but that will take weeks and cost a fortune in electricity).

[openspaceman]

1 hour ago, Dan Maynard said:

And just to add, whether it's been briefly in a kiln or not I'm afraid the bottom line is that it's wet and isn't going to dry well tightly stacked in a cellar.

Only options I can see are to take the wood out and stack it where the wind can blow round it over the summer, or else turn your cellar into a kiln with dehumidifiers and fans (but that will take weeks and cost a fortune in electricity).

I once ran some numbers on this using the necessary air changes over a summer for a cubic metre of stacked wood. It turned out that a PC power supply fan would pass enough air, not that that implies the air circulation inside the wood stack would be  distributed well enough.

[Paul in the woods]

I'm not sure I can add much to the comments already posted.

 

Unless you were promised a certain moisture content or the wood was supplied by an accredited scheme (Woodsure Ready to Burn for example) then I guess they could supply anything.

 

I'm not an expert on meters, just use one to help me season the wood I cut myself. Whilst looking into them it did seem the pin type are more reliable to the scanning method.

 

Unseasoned ash will be about 35 - 40 % moisture so 50 - 70% sounds way out even for unseasoned wood.

 

When you used the pin method on a split log did you push the pins all the way in? On my meter you get a lower reading until the pins are pushed a fair way in. 22%, assuming it's dry basis, would be acceptable. 

 

As has been said, you can dry a sample of wood in your oven to get a better reading (following the advice in the article). If you could get hold of a fresh ash log you could also see what your meter records for that.

[Rob_the_Sparky]

Look at the LONG thread on here about et and dry measurements.  Dry is the water content as a % of the dry weight, Wet is % of the total weight.  I.e. a 50% reading for wet = 100% reading for dry.  It maybe this that is giving you the high numbers.

 

Also in that thread there is input from those who have done the weigh wood, dry in a oven and re-weigh.  They were saying that meters are not that accurate anyway and this is the only right way to get a measurement of any accuracy.

 

Clearly though you have wet logs and the fire temps confirm this.

 

 

Note: Looks like a helpful soul has pinned a message describing meter differences in more detail

Edited March 8, 2021 by Rob_the_Sparky
Observation