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Archive for the ‘Heating with Wood’ Category

…that is, Kerplunk number 2, not Karakoram Mountain #2, the second highest peak in the world above sea level. After the first tree fell without warning, being a seemingly healthy tree and not on a particularly windy day, my friends began to suspect another White Oak tree in their front yard. Was it similarly diseased and fated for freefall? They had a company drop the tree and then called on me to cut it up. I observed that the outer dozen or more rings were indeed darker as if diseased, which you can see in the first picture. It took me over six hours to cut up the branches and part of the trunk. It would have been longer but the local ironworks/woodworker agreed to get the main trunk. Because the tree felling company did not report grounding until late morning, I did not start cutting until 11:30. My friend, the homeowner, came home from work early to clear away brush and firewood. I was cutting pretty much non-stop for 6 hours. My forearms were very weak and achy the next morning.

My stance indicates to me that I was cutting upward to prevent pinching of my saw by the weight on the branch.

Because I knew the iron/woodwork was coming, I cleared the branches off of the main trunk first. I left outriggers to keep the trunk off of the ground and prevent it from rolling over. Then I began to clear the driveway.

I spend a considerable amount of time working outside for which I am thankful. I have however, began wearing light, long-sleeved SPF-50 shirts and hat to protect me from the Sun. My forearms indicate that I spent far too many years baking in sunlight.

There were many forks up the tree because it had been severely topped some time long ago. Don’t trim more than a little from a tree, especially oak trees. It uglifies them and shortens their life.

The ironworker/woodworker has all of the toys. Below he is clearing the smaller pieces in order to drag the trunk down to the driveway. The front and rear wheels of the forklift steer. It is not quite “zero-turn” but close.

I thought that my Husqvarna Rancher 460 with the 2′ bar was quite a lot of saw, but the Stihl was far more powerful and appears to have a 30″ bar.

He cut two logs, a ten foot one and a twelve foot one and loaded them in 30 minutes. I estimated the larger of the two logs to be 3500-4000 lbs based on size and typical weight of green oak wood.*

While I was editing the next picture, I zoomed in to count rings. This is about 22 feet up the trunk on the smaller of the two trees (2 1/2 feet in diameter instead of 3 1/2 feet in diameter of the larger tree). I counted 70 rings. Even if the base revealed 90 years of growth, this was a mere youngin’ in White Oaks trees that can live for 500-600 years.

*60 to 70 lbs per cubic foot- wow! Especially amazing considering the dried oak is 48 lbs/cu.ft

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I am one tired 60 year old this evening*. It rained relentlessly yesterday and last night. The weather forecast suggested cloudy in the morning and sunshine in the afternoon. It was drizzling heavily when I left home this morning. The job I had intended to do was postponed until drier, so I shifted gears to get firewood. I cannot remember a year in the past 37 winters of heating with wood that I began the year with so little firewood. A job estimate I did turned into an opportunity to get wood. The oak tree in question had been down about a year, having died and been cut. It was elevated off of the ground by branches, which allowed it to dry without rotting, and it was about 18 to 20″ in diameter at the base. The wood was sound, sap dried**, and fairly straight grained***. The drizzle quit, the saw was cutting well, and the distance from truck to tree was short. The landowner had even said that I could borrow his hydraulic splitter. After reminding him of this kindness several times, it never materialized. So, after rolling the larger pieces up beside the truck and throwing all of the smaller pieces into the truck, I began to split with my trusty 10-pound sledge hammer and wedges and double bladed axe. I might need to buy some new wedges some time since I have pounded the old ones to about 2/3 their original length over the past 37 years. I split 15 of the 18+/- diameter logs and all of the pile of medium sized logs in the picture. Then I loaded it, hauled it home, and after a large, late lunch, stacked it in the firewood shed. It is time for a sit.

Time for business
Only nine logs at this time; 15 when I rolled them all up.
About halfway there
Not totally volumetrically full, but weight full with trailer attached
Ready to haul
Recycling a stump

Rats, I didn’t have time to workout today. Do you reckon I’m OK skipping a day?

*I asked myself a question you may have asked about my blog writing. Why does he write about everyday events? Who cares and who wants to know? My answer is that my twofold reason for writing this blog is to glorify God and record what I am thinking and doing. I think it does the former by showing His work and provision in the mundane as well as exceptional, and it does in the latter by showing I’m just a common joe going about life.

**Wood may be soaked by rain and still be “dry”. Green wood does not burn well, needing a year for the sap to dry out.

***Straight grained wood is easy to split. Oak is generally so except where there are knots. Some tree species, for example sycamore, twist as they grow and can be difficult to split.

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Heat acts like an invisible fluid that washes over and penetrates through any barrier. The reason I thought about it this morning was the temperature in the house, the difference in temperature from outside, and the feel (comfort level) in the house.

The thermometer, placed on the counter in the center of the house, said 68 degrees, which is a reasonable indoor temperature. But should I start a fire in the stove? Ultimately, for most people, the answer to that question depends on comfort level. Ignoring the real psychological components of comfort level, comfort level depends on heat flow rate.

Heat flow rate is the reason for heat index and chill factor in weather reporting of temperature. An inanimate object feels neither extra hot when it is humid nor extra cold when the wind is blowing. The temperature at which it settles is determined solely by the average rate of vibration of its molecules (i.e. temperature). 

But when an object like a thermostated heater or warm blooded mammal or human is warmer than its surroundings and produces heat to maintain that difference, heat flow rate is crucial to comfort and even survival.

For a fuller understanding of this concept. let us posit two facts:

  1. Heat always flows from warmer to cooler.

  2. Heat Flow Rate is     Screen Shot 2018-12-08 at 6.05.10 PM,

where Q is heat, t is time, K is conductivity, dT is change in temperature, and l is length (distance or thickness) of heat flow, and the combination of dT/l is the temperature gradient.

Since in winter I heat with wood for the purpose of keeping us warm and feeling warm, I will consider the situation of heat flowing out of our bodies. Unless I am sitting by the woodstove, I am warmer than the room and heat is leaving me.

The greater the area (A) of my skin exposed to the surroundings, the faster I cool off. For this reason, you don’t expose flesh to the air on an extremely cold day because the heat flow rate is so great from any area of  your body that it can’t provide enough heat to prevent your flesh from freezing.

The greater the temperature difference (dT) between me and the environment cooling me, the faster I cool off. Our bodies are constantly radiating heat to the cooler surroundings. If you have ever worked in an unheated building with a concrete floor, you know that it is very hard to keep warm. You can feel the concrete zapping heat out of you (you radiating to it, in fact).

The shorter the distance (l) for the heat to flow to reach the cooler temperature, the faster I cool off. The thickness is the reason thicker insulation works better. More thickness of a substance that slows heat flow rate slows it more. Insulation, be it pink or down or quilt is really just a function of how much non-convecting air is trapped in the insulating layer. Air is an excellent insulator, which brings us to the next component.

And the better the material is at conducting heat (thermal conductivity (K)) off of me, the faster I cool off. Conversely, the reason air is poor conductor of heat is the distance between molecules. On the other hand, since it is a fluid, it is a decent convector (heat transfer by flow of a fluid), and it provides little resistance to radiation, since there is less matter than most materials to absorb or radiate back the heat. When you put a warm hand on a cold, wooden table it won’t feel very cold, but on a cold, metal appliance it will. This increased flow happens because the metal has a far greater thermal conductivity than an insulator like wood.

Soooooo, back to my question. Should I start a fire when the core of the house is 68 degrees? Considering this situation, I ask myself several questions. What is the temperature outside? Is there a strong wind cooling the house? Is there cloud cover to prevent cooling at night or prevent warming during the day? Is there a temperature trend up or down from the present reading of 68 degrees because of internal or external changes to the house? About this time, those of you who have thermostats that do all of this “thinking” for you should stop taking it for granted. It is a relatively old technology, but not an altogether simple or trivial one.

In terms of comfort level, it can be 68 degrees in the core of the house and feel quite chilly because the outside is removing heat rapidly. This situation will result in the peripheral (near the outside walls) temperature being several degrees cooler.  I used to have my indoor/outdoor thermometer on a window sill. It consistently read cooler than the one I have now. My new thermometer wouldn’t fit on the sill. It would probably be easier to not think about it if I had a thermometer in the center of the house and on the window sill. Then I would have an approximation of the heat flow rate out of the house, but that would make me less truly aware of my surroundings. I have to walk past the central thermometer and past the window to get to the refrigerator and the stove to make my breakfast anyway, so I feel the temperature difference from core to periphery. I do not, however, usually think much about the various components of heat flow rate, because I am only barely awake at 5:15 in the morning.

101_1604

Not time for a fire, yet (I need to reset the clock.)

P.S. If you read this far, I surmise that you are either a science geek or a particular friend. Either way, thanks for reading, and glory to God for His ordered universe and minds to make sense out of it.

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