Spruce firewood quality

Cavanshooter

Is spruce timber any good for firewood and how much would you sell a fertiliser bag for? Thanks

wayoutwest

When FULLY seasoned Spruce is a good, hot and fast burning firewood.When not fully seasoned, it is cr★p.
If you buy a large net bag of logs from shop/garage for 4 or 5 euro and empty them into a fertilliser bag (larger than '25 kilo feed bags) I would think that it would be around three quarters full.

Oldtree

It spits a lot so really need a fireguard and due to the high resin content you need to clean your chimney more regularly.

wayoutwest

Spruce is better off burnt in stoves that are running at high temperature (not in 'slumbering' mode) to ensure that any resins are efficiently combusted in the firebox . Loading up a stove with Spruce and closing down the air supply is the quickest way to coat your chimney/liner in thick, treacle -like tar that cannot be cleaned with brushes and will fuel a very nasty chimney fire at some point. 'Shutting down' a stove that is full of half seasoned Spruce is THE worst thing you can do for your chimney and your(and everybody elses') enviroment.

Jack180570

Cavanshooter wrote: »

Is spruce timber any good for firewood and how much would you sell a fertiliser bag for? Thanks

Spruce will make good firewood if it is properly dry, has to be under 25% MC and ideally 20%. The requirement of being properly dry applies to ALL timber that is going to be burned.

Spruce is a softwood and is less dense than hardwoods, therefore, for the same VOLUME of spruce you will get less heat from it than from a hardwood.
However, when you compare spruce to hardwood (at the same moisture content) on a weight basis you will get more heat from the spruce due to the higher resin content.

Spruce is an exceptionally clean burning firewood especially when you compare it it the larch for instance. If it is properly seasoned (under 25%MC) you will have no issue with extra chimney cleaning. We have now completed our third year burning spruce (on its own) in a boru insert stove and we have not had to clean the chimney yet/

Pricewise its difficult to say but in limerick/kerry 4.50 seems to be a popular price for the fertiliser bags of logs

50HX

how do you test the MC of timer??

Oldtree

50HX wrote: »

how do you test the MC of timer??

With somthing like this, but its just an example I have one similar but not this make

http://www.ebay.ie/itm/3In1-Wood-Moisture-Log-Damp-Meter-Concrete-Temperature-Digital-Detector-Mini-UK-/161518726452?hash=item259b442d34:g:9k4AAOSw2XFUisDB

wayoutwest

Logs that are reading 25%MC can't be described as 'properly seasoned'! ......'properly seasoning' maybe.
Fully seasoned (air dried) logs should read 18%MC or LESS. A 25% log will hiss small amounts of steam and noticeably give off less heat than an 18% log .

Jack180570

wayoutwest wrote: »

Logs that are reading 25%MC can't be described as 'properly seasoned'! ......'properly seasoning' maybe.
Fully seasoned (air dried) logs should read 18%MC or LESS. A 25% log will hiss small amounts of steam and noticeably give off less heat than an 18% log .

I couldn't agree with you Wayoutwest...
...
...
From reading at the various woodfuel quality standards in Ireland, the UK, Europe and Internationally, the standard for dryness of firewood seems to be either 25% (for air dried) or 20% for kiln dried.

I would be very grateful if you could let me know the sources of your information, especially regarding the 18% figure for air-dried firewood.

I would agree with you that firewood at 18% is superior to firewood at under 25% and clearly it will give off less moisture when burned.

Can you let me know what method and equipment do you use to establish the moisture content of your firewood and also whether you are quoting the figures on a wet basis or a dry basis.

Finally, how long does it take you to get the firewood to 18% MC and is it hardwood or softwood.

Thanks in advance,

Jack

wayoutwest

Hi Jack - Not sure whether firewood moisture meters are expressing dry or wet basis. I've had a few of these €20 meters, and they all recommend the 16 -20% band of moisture content. They all seem to have been consistant with each other, in that if I measure air dried wood,that I know can't get any drier ( ie: 3 years will ventilated and covered) it reads 17-18% .Joinery wood and kindling seems to read around the 10 -14% band. Further up the scale, I know from experience that if I burn Spruce that reads 25% (on the meter) then I know that the fire won't be effecient.
Found this passage somewhere, that I 100% agree with (and seems to tally with my firewood moisture meter readings)......
"The right band of M.C is beween 15 -20%. When you get much over 20% you start to see symptoms of sluggish ignition and the inability to turn down the air without extinguishing the flames.Toward 30% water bubbles from the end grain and is hard to get a clean burn until the wood is almost to the charcoal stage".
Check out U.K website Arbtalk - they have a good firewood forum with contributors in the firewood business - lots of people on there are aiming for 18% (air dried).
Any readings I make are from a sample log which is then split so the meter can probe the middle, rather than the outside or end grain.
Drying times can vary depending on species, size of log, time of year felled, whether I put it in large (covered + ventilated) shelter or in cubic metre one (faster). Two Summers minimum drying would be my rough guide (esp. Spruce).

Blackcurrants

Spruce bought in lengths and stacked with their butts orientated towards the prevailing wind and uncovered can dry from 60%-65% mc down to 17% mc within 7-9 months. These months must include May-September. (this is for small to med diameter logs)
We use the oven test to for mc%. Take a sample of saw dust or chip and weigh it, then put in an oven at 105c for 24hrs or until the weight stops going down. Re-weigh the sample and divide the difference by the wet weight and multiply the result by 100 to get the most accurate MC reading. Moisture meters are good at giving an indication of MC % but can be wildly inaccurate. Always measure across the grain and not with it.
Hardwood takes longer to dry but ash can come out of the woods as low as 45%mc. Massive hardwood logs need to be cut into rings at a minimum to dry down properly. For stoves low MC is much more important than species or whether is it hardwood or softwood. With an open fire you really need to use hardwood for a slower burn but with 80% of your money going up the chimney you'd be best with a mix of coal with it. Don't mix coal and timber in your stove especially if it is wetter timber as the high amount of sulphur dioxide generated can corrode your system.

Jack180570

wayoutwest wrote: »

Hi Jack - Not sure whether firewood moisture meters are expressing dry or wet basis. I've had a few of these €20 meters, and they all recommend the 16 -20% band of moisture content. They all seem to have been consistant with each other, in that if I measure air dried wood,that I know can't get any drier ( ie: 3 years will ventilated and covered) it reads 17-18% .Joinery wood and kindling seems to read around the 10 -14% band. Further up the scale, I know from experience that if I burn Spruce that reads 25% (on the meter) then I know that the fire won't be effecient.
Found this passage somewhere, that I 100% agree with (and seems to tally with my firewood moisture meter readings)......
"The right band of M.C is beween 15 -20%. When you get much over 20% you start to see symptoms of sluggish ignition and the inability to turn down the air without extinguishing the flames.Toward 30% water bubbles from the end grain and is hard to get a clean burn until the wood is almost to the charcoal stage".
Check out U.K website Arbtalk - they have a good firewood forum with contributors in the firewood business - lots of people on there are aiming for 18% (air dried).
Any readings I make are from a sample log which is then split so the meter can probe the middle, rather than the outside or end grain.
Drying times can vary depending on species, size of log, time of year felled, whether I put it in large (covered + ventilated) shelter or in cubic metre one (faster). Two Summers minimum drying would be my rough guide (esp. Spruce).

Sorry for the delay replying wayoutwest...
AFAIK most moisture meters output the moisture content reading on a 'dry basis'. The internationally accepted way of expressing moisture content of firewood is on a 'wet basis'.
This in practice means that if the meter is accurate and you are getting a reading of 25% (DB) then this converts to 20% MC on a wet basis.
Overall, from our own experience and test, from scientific tests undertaken on moisture meters and from manufacturers recommendations, moisture meter readings are not accurate and some of the cheaper meters can be out 3-5% at under FSP and 5-20% out over that.
We don't trust them and we don't use them because we need to be 100% accurate and therefore we test all our firewood using the oven dry test method which is accurate and reliable.

The passage you quote is from woodheat.org as far as I know. They are based in Canada. I do agree that firewood at 20%MC is better than 25%MC and should be what firewood producers aim for.
The advice that (air) seasoned wood in Canada should be 20% or lower is correct because that is an achievable air dried MC to produce due to the lower equilibrium moisture content (EMC) in Canada.
In Ireland EMC is generally regarded as being between 18 and 22% due to our climate and therefore under 20% air dried firewood is extremely difficult to produce.
In the UK for example, the term 'seasoned firewood' is often stated along with a moisture content of 40% which one could not consider seasoned.
The UK has a quality assurance scheme (HETAS) and its basic requirement is that firewood producers must have their firewood under 25% to be sold under the scheme.

In terms of firewood in Ireland, the Wood Fuel Quality Assurance scheme similarly has a requirement that firewood should be under 25% to be sold under their scheme. Diligent WFQA certified firewood producers will ensure that all pieces of firewood are under 25% and in the process this will result in the average MC of their firewood being 20-22%MC which is only a fraction over the Kiln Dried standard of being under 20%MC.. very good firewood in my humble opinion.

One of my big difficulties when people say that this MC% is good and that MC% is bad is that if they are not testing the firewood properly (the oven dry test) then the figures are meaningless. Moisture meters are ok for approximate readings or for personal use on ones own firewood, they are not reliable for commercial use (firewood producers testing firewood to be sold) or indeed for checking firewood that one purchases.

Here is a video of testing a piece of firewood with two different moisture meters... https://www.facebook.com/woodfuel.heating.the.nation/videos/136221443220578/

Jack180570

Blackcurrants wrote: »

Spruce bought in lengths and stacked with their butts orientated towards the prevailing wind and uncovered can dry from 60%-65% mc down to 17% mc within 7-9 months. These months must include May-September. (this is for small to med diameter logs)
We use the oven test to for mc%. Take a sample of saw dust or chip and weigh it, then put in an oven at 105c for 24hrs or until the weight stops going down. Re-weigh the sample and divide the difference by the wet weight and multiply the result by 100 to get the most accurate MC reading. Moisture meters are good at giving an indication of MC % but can be wildly inaccurate. Always measure across the grain and not with it.
Hardwood takes longer to dry but ash can come out of the woods as low as 45%mc. Massive hardwood logs need to be cut into rings at a minimum to dry down properly. For stoves low MC is much more important than species or whether is it hardwood or softwood. With an open fire you really need to use hardwood for a slower burn but with 80% of your money going up the chimney you'd be best with a mix of coal with it. Don't mix coal and timber in your stove especially if it is wetter timber as the high amount of sulphur dioxide generated can corrode your system.

Fair Play to you Blackcurrants...
that is a very knowledgable reply :-)
Are you certified under WFQA?