Yet Another Drying Firewood in a Greenhouse...

creztor

New Member
Nov 13, 2018
4
Australia
OK, so I looked through the already existing threads here and hoping can get some feedback on drying firewood in a greenhouse. I have a 6m (approx 19 feet) by 3m (approx 10 feet) greenhouse (see attached picture). It's just a standard cheap ebay kit. I put black plastic down on the ground and then blue tarp over this to reduce amount of moisture entering the greenhouse. Both sides have pallets running down them. I stacked the wood in rows of 3 (show in pictures). I stacked both sides about a metre high with dripping wet wood (stringybark). I didn't measure the MC but it was cut fresh. I kept the greenhouse completely closed (windows on both side shut). At first I did not have ventilation (whirlybird) on the top. After a while and reading here I put in a whirlybird to reduce condensation that was forming in the early mornings of winter and try to replace the air to improve drying times. So, after probably 8 months in the greenhouse the MC of the wood is down to around 15%. Based on what I've read here, that's rather poor. Seems people are getting under 10% MC in less than 6 months.

So, my questions. First, should I change how the wood is stacked. The way it is I doubt the middle row and wood towards the bottom is getting any or getting limited air circulation. However, from pictures I've seen here people don't seem to be leaving much space between rows, or it's possible I can't see clearly in the pictures. Second, ventilation. I am thinking to either put a 12v fan under the whirlybird and have it connected directly to a solar panel via buck converter. This way it will only come on when there's enough sun providing power. Should I also open the windows on the sides? Doing this however will obviously reduce the heat in the greenhouse but it will improve ventilation.

I'm OK with the setup but think I should be getting better results. Do I need to change how I stack the wood or does it not matter and I need to improve ventilation? Windows open with fan under whirlybird or fan on either end, one sucking and one blowing. I'm in Tasmania, Australia. Our winters are warm compared to what people here experience. Winter ranges 3 - 11 degree Celsius (37 - 51) and summer 17 - 23 (62 - 73). Appreciate any feedback. Thanks.
 

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Woodsplitter67

Minister of Fire
Jan 19, 2017
1,220
Woolwich nj
can you post what your climate was while you were doing this.. like when you started was it mid summer or late fall... whats the temperature of the greenhouse during this time period..as well as Relative humidity during the day inside to greenhouse.. for example.. my greenhouse the RH right now is about 65% at night to early morning and during the day when the inside temp is 85 to 90 degrees the RH drops to 5%... J just as a heads up.. your greenhouse is a tunnel style so you vent it at the Gable ends.. pulling the air through the tunnel.. and not out the top .
 

moresnow

Minister of Fire
Jan 13, 2015
1,174
Iowa
15% = primo. Note how you are getting these results in fine detail. If you try improvements and they fail. Revert to the way it was!
Winter ranges 3 - 11 degree Celsius (37 - 51) and summer 17 - 23 (62 - 73).
What? No 100F summer days with 100% humidity? No -35F winter nights with constant 30+mph sustained winds? Why I tell ya. Tasmania is looking top notch:cool:
 

creztor

New Member
Nov 13, 2018
4
Australia
can you post what your climate was while you were doing this.. like when you started was it mid summer or late fall... whats the temperature of the greenhouse during this time period..as well as Relative humidity during the day inside to greenhouse..J just as a heads up.. your greenhouse is a tunnel style so you vent it at the Gable ends.. pulling the air through the tunnel.. and not out the top .
Started in mid summer. I did log numbers but three them away. However, temps would have been 30 to 50 (86 to 122) day time but I can only guess RH. The temp varies a lot. With sun out full it'll hit 50+ but if it goes behind a cloud for a while it drops off.

I understand others put fans on either end to circulate air. If I open the windows on both sides, would this achieve the same thing? Air comes in from sides and is sucked out through top, replacing the humid air inside? Which is why I'm not sure if how the wood is stacked is limiting airflow or does it not matter.

I can definitely cut another opening at the far end, I just thought the goal was to replace humid air with less humid air, so vent at top and maybe opening side windows would help. Thanks for the info!
 

creztor

New Member
Nov 13, 2018
4
Australia
What? No 100F summer days with 100% humidity? No -35F winter nights with constant 30+mph sustained winds? Why I tell ya. Tasmania is looking top notch:cool:
I look at people's pictures here and I am amazed. Working in the snow and all the rest. Truly impressed with the conditions people live through. Tasmania is great just no work, but that's the case everywhere now. I'm ok with the 15% but I see people hitting under 10% in snow conditions, do I'm doing something wrong.
 

Woodsplitter67

Minister of Fire
Jan 19, 2017
1,220
Woolwich nj
Started in mid summer. I did log numbers but three them away. However, temps would have been 30 to 50 (86 to 122) day time but I can only guess RH. The temp varies a lot. With sun out full it'll hit 50+ but if it goes behind a cloud for a while it drops off.

I understand others put fans on either end to circulate air. If I open the windows on both sides, would this achieve the same thing? Air comes in from sides and is sucked out through top, replacing the humid air inside? Which is why I'm not sure if how the wood is stacked is limiting airflow or does it not matter.

I can definitely cut another opening at the far end, I just thought the goal was to replace humid air with less humid air, so vent at top and maybe opening side windows would help. Thanks for the info!
a greenhouse is a little different than a kiln. you have alot more volume of space.. aka... air. the heated air will actually hold more water than cool air so with temps inside of 122 degrees you RH will be alot lower than the outside air you need to keep a Thermometer as well as something to measure RH.. mine does both.. reading this inside the green house will help you regulate what's going on inside.. again it would be best to draw the air through the tunnel.. but you need to regulate the temp inside.. as not to draw to little slowing the seasoning or ro to much which will cool the greenhouse slowing it also.. there's a sweet spot you'll need to fined.. you need MC of the wood when you start, temp and humidity inside the greenhouse and adjust the air going through..
 

JohnDolz

Minister of Fire
Dec 29, 2015
535
Burlington, CT
I look at people's pictures here and I am amazed. Working in the snow and all the rest. Truly impressed with the conditions people live through. Tasmania is great just no work, but that's the case everywhere now. I'm ok with the 15% but I see people hitting under 10% in snow conditions, do I'm doing something wrong.
As another poster mentioned 15% is great. I know for my boiler I try not to have wood go down to 10% of below - are you trying to get that low or just curious as you expected dryer results?