firewood kiln - How do you build one? does anyone know

[arboriculturist]

2 minutes, max. The firebox is 0.84 cubic metres. Offcuts are cut with the chainsaw to 70 cm, or thereabouts. It just burns quite quickly due to the forced airflow.

 

How is the airflow fan controlled or is it un-controllable?

 

What timber volume do you load each hour?

[Big J]

Fans are thermostatically controlled. Once the boiler reaches a temperature (as indicated on the display, though not exactly sure what it corresponds to) of 33c, the fans kick on. Over 90c is too hot and it beeps at you to tell you so. Air flow is 4 cubic metres per second, and with a boiler temperture of 80c, air being pumped out about 100-120c.

 

The boiler is supposed to burn about 47kg of wood per hour, which is probably about right.

[arboriculturist]

Fans are thermostatically controlled. Once the boiler reaches a temperature (as indicated on the display, though not exactly sure what it corresponds to) of 33c, the fans kick on. Over 90c is too hot and it beeps at you to tell you so. Air flow is 4 cubic metres per second, and with a boiler temperture of 80c, air being pumped out about 100-120c.

 

The boiler is supposed to burn about 47kg of wood per hour, which is probably about right.

 

564kg / 24 hrs. How many Kw? Are you drying 20m3 per cycle? Hardwood?

 

The fan acting on the fuel is thermostatically controlled - yes?

 

The outlet fan cycles on at 33c - what temp. c off ?

[Big J]

564kg / 24 hrs. How many Kw? Are you drying 20m3 per cycle? Hardwood?

 

The fan acting on the fuel is thermostatically controlled - yes?

 

The outlet fan cycles on at 33c - what temp. c off ?

 

Can't run it for 24hrs. More like 9hrs. The boiler is rated to 233kw, but I doubt it really produces that and some of it is lost from the external casing as it's sited outside of the kiln. Softwood on this cycle, reasonably freshly felled, reasonably dry softwood thereafter.

 

Fans are thermostically controlled and come on and off at 33c.

[arboriculturist]

Can't run it for 24hrs. More like 9hrs. The boiler is rated to 233kw, but I doubt it really produces that and some of it is lost from the external casing as it's sited outside of the kiln. Softwood on this cycle, reasonably freshly felled, reasonably dry softwood thereafter.

 

Fans are thermostically controlled and come on and off at 33c.

 

Yes, no night stoking.

 

It will be producing around 175 nominal burning sub 20% MC fuel. Don't burn over 20% MC.

 

They may come on at 33 but will cut out below that temp when the low limit signals switch.

 

Does a fan act on the fuel heating the unit?

[Big J]

Yes, there is a fairly strong fan on the intake, hence the rapid burn.

 

As regards sub 20% fuel, well at the moment the offcuts I have to hand are above that, but I'm not having any issues keeping the boiler in the 60-80c zone. They might not be that far over 20%.

 

What do you reckon? I'm thinking in the ball park of 3-4 days with this wetter softwood, perhaps half that with dry spruce.

[arboriculturist]

Yes, there is a fairly strong fan on the intake, hence the rapid burn.

 

As regards sub 20% fuel, well at the moment the offcuts I have to hand are above that, but I'm not having any issues keeping the boiler in the 60-80c zone. They might not be that far over 20%.

 

What do you reckon? I'm thinking in the ball park of 3-4 days with this wetter softwood, perhaps half that with dry spruce.

 

3.5 days min Jon as your insulated, but only 9 hrs burn time. Dry spruce faster of course, 2.5 - not greatest firewood and won't sell well.

 

You will struggle i'm sorry to say unless you can offer hardwood in the mix.

[Big J]

It just doesn't add up figures wise. With the drier spruce I spoke of, my production cost is £18.50 a cubic metre. I can't see it being anything less than double on hardwoods.

 

Presumably double the drying time on sycamore/beech etc?

[arboriculturist]

It just doesn't add up figures wise. With the drier spruce I spoke of, my production cost is £18.50 a cubic metre. I can't see it being anything less than double on hardwoods.

 

Presumably double the drying time on sycamore/beech etc?

 

Ok, so wholesale dry soft, but retailers will want hard also.

 

Have you got any firm offers of intent from any Retailers. How will you deliver? Serious retailers will want it containerised. Transport brings your margin right down.

 

I tend to look at negatives 1st and never leave a stone unturned when it comes to 'knowing the market'. There are some big players on here but most buy hard from across the water or have their own setups.

 

I've had enquiries but the transport kills it unless very local. I hope I am mis-informed in your case as you are regionally different.

[briquette_seller]

Softwood sells, but the price has to be right, in my experience.

 

I have no kiln experience, so excuse me if this is a stupid question/comment, but wont the kiln cause more of the bark to come off the logs, giving a quality issue?

 

Certain softwoods can be a pain for this, even air drying.

 

Ian guessing this will be a greater issue as your force drying.

 

That's assuming your processing fresh felled softwood.