Firewood moisture content

[Central]

I have recently installed a wood gasification boiler, and what with the wet summer we had last year there was not much seasoned timber around, so when we found a supplier who had kiln dried hardwood, so we went with that.

 

We discussed it with the installer who measured it with a moisture meter at 13-16%.

 

The firewood was supplied In sections about 8 inches long and about 4 inches across typically. Some a bit more and some a bit less.

 

Today a took my axe and split one of the larger bits and found the mc to be 36% in the very centre, falling back to the mid teens at the edges.

 

So my question is, how are you ever to know for sure that what you are burning is dry enough, without cutting it up into matches?

 

I have found traces of pitch in the lower chamber by the from door, but nowhere else. There is quite a bit of pitch in the upper chamber. I am a bit concerned we may have reduced the efficiency of our boiler.

 

When it was installed I recall watching the temperature gauges in the accumulator tanks rise so quickly you could see the needle moving. That is not now the case.

[muldonach]

I have recently installed a wood gasification boiler, and what with the wet summer we had last year there was not much seasoned timber around, so when we found a supplier who had kiln dried hardwood, so we went with that.

 

We discussed it with the installer who measured it with a moisture meter at 13-16%.

 

The firewood was supplied In sections about 8 inches long and about 4 inches across typically. Some a bit more and some a bit less.

 

Today a took my axe and split one of the larger bits and found the mc to be 36% in the very centre, falling back to the mid teens at the edges.

 

So my question is, how are you ever to know for sure that what you are burning is dry enough, without cutting it up into matches?

 

I have found traces of pitch in the lower chamber by the from door, but nowhere else. There is quite a bit of pitch in the upper chamber. I am a bit concerned we may have reduced the efficiency of our boiler.

 

When it was installed I recall watching the temperature gauges in the accumulator tanks rise so quickly you could see the needle moving. That is not now the case.

 

Always measure moisture content on a freshly split face - which is what your installer should have done.

 

You can worry too much about moisture content but 36% is a bit high - chuck all the big bits to one side and split them down smaller.Get your next supply organised and make sure it is more homogenous.

 

Use some small firewood to get a good hot fire going and you will get rid of the pitch.

 

A visible temperature rise in an accumulator tank over a short timescale does not sound correct - you are heating a relatively large volume of water - it should take a while to heat

 

Cheers

mac

[BestFirewoodUK]

Right,

 

Doesn't matter how long you going to season wood it will always be more dry at the edges and more wet in the middle.

 

Cheap option: Look out for a supplier who offers smaller ( Thinner ) lumps of wood.

Another way is to have briquettes or pellets as these have 10-15% MC but they do cost more.

 

P.S even if wood has been kiln dried, big lumps of wood may still be fairly wet 30-35% closer to middle. Its down to the manufacturer to split the wood promptly.

[County4x4]

Briquettes generally come in at around 5% moisture - pellets are a bit higher, but would normally require a dedicated stove/boiler to burn them properly - you couldn't just bung them in an appliance designed to burn logs.

 

In energy terms, briquettes often work out a fair bit cheaper than logs - unless you're getting logs from your own woodland or very cheap. KIln dried logs are usually around 18 - 20% (and often no drier than well seasoned logs dried naturally, as well as being a lot more expensive!) Briquettes are always exactly the same from load to load and season to season, though you'll find that extruded ones last a lot longer than pressed ones.

[East Anglian landscaping]

Hi we have an eco angus 25kw boiler and i throw allsorts in it we get quite a lot of pitch in the top chamber but nothing in the bottom one i would make sure the fan is working correctly as the fact you have pitch in the bottom chamber would indicate that you are not getting proper combustion ours burns and leaves a little ash and nothing else

[Alycidon]

If you have heat transfer tubes in your boiler that the smoke flows through, if so these will want a clean through on a weekly basis as they get sooted up reducing heat transfer.

 

A

[Joy Yeomans]

id get a new supplier who can give you a proper log, m/c measured from the split surface as should be done as standard practice.

[Central]

Thanks for the responses guys. Really helpful and reassuring.

 

we have a bit of woodland with a number of dead trees standing waiting to be felled. We hope those will be dry enough to be used next winter as they have been standing dead a few years.

 

We also have space to let a good 30m3 of timber dry over a year or two.

 

It's more the short term that concerns us, finding enough dry wood for the rest of this year and also, our heat exchanger tubes clogging up. I have no idea how effective the handle on the side of the boiler is at cleaning those.

 

As has been mentioned, we have also have a lot of pitch in the top chamber. at the moment, very little in bottom chamber, only a trace by the door. once i have the ember layer and add in the dry hardwood it will gasify straight away.

 

in terms of ash, I could maybe fill a bucket with ash after 2 weeks of burning.

 

When I look at the what's at the bottom of the flue, I doubt I could fill a tea spoon with what is there after a months use.

[renewablejohn]

You could buy solar kiln dried logs from ourselves. We guarantee to be less than 20% moisture content and always have a moisture meter available to prove the point on delivery. As part of our quality control the date when the logs where split and put in the solar kiln is attached to the IBC container so we can do a proper stock rotation.

[gensetsteve]

I have recently installed a wood gasification boiler, and what with the wet summer we had last year there was not much seasoned timber around, so when we found a supplier who had kiln dried hardwood, so we went with that.

 

We discussed it with the installer who measured it with a moisture meter at 13-16%.

 

The firewood was supplied In sections about 8 inches long and about 4 inches across typically. Some a bit more and some a bit less.

 

Today a took my axe and split one of the larger bits and found the mc to be 36% in the very centre, falling back to the mid teens at the edges.

 

So my question is, how are you ever to know for sure that what you are burning is dry enough, without cutting it up into matches?

 

I have found traces of pitch in the lower chamber by the from door, but nowhere else. There is quite a bit of pitch in the upper chamber. I am a bit concerned we may have reduced the efficiency of our boiler.

 

When it was installed I recall watching the temperature gauges in the accumulator tanks rise so quickly you could see the needle moving. That is not now the case.

 

Thats the difference between kiln dried for a few hrs and solar kiln dried for weeks. There is no advantage to kiln drying it just uses fossil fuels to achieve what nature does in 12 months for free even outside in the rain. Once you get your immediate problem sorted get 2 years in front of the job