Firewood moisture meters, and "wet basis" vs "dry basis"

[carbs for arbs]

Hi all

 

I'm getting a stove installed in a few weeks...  Can't wait!  We've got some 3 year old ash and oak that hasn't been chopped yet.  It spent it's first 18 months or so in the elements but has since been under a tarp.  I'll be getting to it in the next few days but once processed I'll want to check it for moisture content.  If it's too high I can buy some logs in for now and use that next year.

 

I ordered one of these as it seemed to get good enough reviews:

 

https://www.amazon.co.uk/gp/product/B003CSNV2Q/ref=ask_ql_qh_dp_hza

 

But I then started reading about "wet basis" vs "dry basis" and I've ended up right confused!  Can anyone explain it to me, and especially what I need and what this unit is likely to be.  I've asked on Amazon and been told it likely gives measurements on a "dry basis".  

 

Many thanks

 

 

Edited January 29, 2021 by carbs for arbs

[Woodworks]

9 minutes ago, carbs for arbs said:

Hi all

 

I'm getting a stove installed in a few weeks...  Can't wait!  We've got some 3 year old ash and oak that hasn't been chopped yet.  It spent it's first 18 months or so in the elements but has since been under a tarp.  I'll be getting to it in the next few days but once processed I'll want to check it for moisture content.  If it's too high I can buy some logs in for now and use that next year.

 

I ordered one of these as it seemed to get good enough reviews:

 

Brennenstuhl Moisture Detector MD (Moisture Meter for Wood/Walls/Building Material, with LCD Display) Anthracite/Yellow: Amazon.co.uk: DIY & Tools

WWW.AMAZON.CO.UK

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Shop Brennenstuhl Moisture Detector MD (Moisture Meter for Wood/Walls/Building Material, with LCD Display) Anthracite/Yellow. Free delivery on eligible orders of £20 or...

 

But I then started reading about "wet basis" vs "dry basis" and I've ended up right confused!  Can anyone explain it to me, and especially what I need and what this unit is likely to be.  I've asked on Amazon and been told it likely gives measurements on a "dry basis".  

 

Many thank

On that other thread Openspacman made up a very handy conversion chart. So the target for nice logs is 20% on the wet basis which will equate to 25% on a dry basis. Get them reading below 25% on that meter and they should burn fine

[carbs for arbs]

How bizarre!  I have a two screen PC set up and was literally looking at the graph on the other screen when your reply came in!

[carbs for arbs]

I was also going to add that I know the meters are not very accurate.  But as a novice I don't think it can do any harm using one, so long as I keep the inaccuracy in mind, and also use it wisely (compare with other wood, get a sense of how it reads things relatively, visually inspect the wood and knock two bits together, etc).  

 

Cheers

[carbs for arbs]

For the benefit of anyone coming across this in the future, to save you finding it the table mentioned can be found halfway down this page:

 

https://arbtalk.co.uk/forums/topic/92256-moisture-content-measurements-logs/page/3/#comments

 

[openspaceman]

1 hour ago, carbs for arbs said:

For the benefit of anyone coming across this in the future, to save you finding it the table mentioned can be found halfway down this page:

 

https://arbtalk.co.uk/forums/topic/92256-moisture-content-measurements-logs/page/3/#comments

 

A more recent one

 

https://arbtalk.co.uk/forums/topic/124043-how-does-one-keep-logs-at-20-at-this-time-of-year/?do=findComment&comment=1856466

 

[openspaceman]

1 hour ago, carbs for arbs said:

I was also going to add that I know the meters are not very accurate.  But as a novice I don't think it can do any harm using one, so long as I keep the inaccuracy in mind, and also use it wisely (compare with other wood, get a sense of how it reads things relatively, visually inspect the wood and knock two bits together, etc).  

 

Cheers

I'm not sure they are not accurate they are certainly quick, I simply don't own one. No harm in occasionally checking it by drying a log now and again. The thing is to sink the probes into a freshly split piece of wood as the middle is likely wetter than the outside.

[carbs for arbs]

I've been reading the other threads on this forum RE MC and meters, as linked above.  They're very helpful *thumbs up*

 

Interestingly, having been in touch with someone at Brennenstuhl he seems to think their meter measures on a Wet Basis.  But then his explanations seem rather confused and without wanting to sound like an arse, I'm not sure he knows the difference between WWB and DWB and is quite muddled as a result!  Likewise the Amazon answers; some of them miss the point completely.  But do you think it is safe to say that that meter is definitely dry basis?

 

I've also been chatting with someone at  StovesOnline, who - contrary to the above - totally gets it.  In fact, it was the StovesOnline page for their meter that put me onto this whole topic in the first place.  The meter they sell is one of the (or maybe just "the") only ones that explains the difference, explains what their meter is, and tells you why it matters: 

 

https://www.stovesonline.co.uk/firewood-moisture-meter.html

 

So credit to him/them I must say.  

 

I have been thinking though.  If part of the calculation is based on the wood weight, how does the meter determine this?  Is it because wood has a consistent weight?  And if so, is that why some meters allow you to select what type of wood you are measuring, so it can adjust the weight accordingly?  Or is there more to it than that?  Not sure if this is a case of 2+2=7, or if I have fumbled way my towards understanding something!  

 

Cheers  

 

 

 

 

 

  

 

 

[TuscanPhil]

Another one regarding Moisture Meters you might not have seen. 

 

[Paul in the woods]

I think the simple answer is unless a moisture meter clearly states what basis it uses you cannot rely on it. If you're a commercial producer I would expect you'd need a suitable meter and be able to prove what basis it uses.

 

As for a private user, you should be able to work out what basis it uses by fully drying a piece of wood. @openspaceman has described this process in other threads.

 

It would be nice if woodsure or a similar body provided a list of meters and the basis they use. Might be worth emailing them?