Outdoor Wood Furnace Info
Outdoor Furnaces - Manufacturers WITH EPA-Certified Models => Central Boiler => Topic started by: Ridgekid on December 01, 2011, 11:38:33 AM
-
In the last 24 hours the weather dipped to the lowest numbers this season. So naturally I thought it meant time to put more than normal wood into the Green Dragon. Doesn't seem to be the case.
In the last 36 hours the Green Dragon went through 14 Burns on 12 pieces of wood. The last three pieces being added at 9AM this morning. My guess she is burning some of that stored energy (creosote) that she formed over the last few weeks. Firebox sure looks better this morning.
-
The extra btu's had to come from somewhere
-
I agree. Or it's more efficient in colder weather? :thumbup:
In the last 56 hours I went through 20 burns on 18 pieces of wood. It's getting close to adding some more wood. I can tell by the amount of smoke, or lack of smoke, she will need wood soon. Thermostat is set at 73* during the day and 71* at night.
At this rate, I'm burning less wood then my indoor unit did. Of course the indoor unit could not be controlled by the thermostat and we were usually roasting. Temperature control was shedding clothes, cracking windows.
With a indoor unit the infamous pot of water had to be put on the indoor unit to maintain some moisture in the house. Now we don't have a issue. Not one static shock from it being too dry.
In short, I wish I would of done this years ago.
-
It's still a bit early to draw any conclusions. You should have a good handle on it by spring. I have found your data quite interesting and have started to take some of my own. The best thing about hard numbers is that it is easier to gauge any changes that one might make rather than relying on a subjective memory. I can't speak for everyone of course but I can say my memory is excellent but unfortunately it's also short.
-
Without a doubt, tracking heat demand and wood usage that RidgeKid provides is a huge help. Quite frankly, I get surprised all the time with my 5036 and the amount of wood it uses when the temperature drops into the single digits. You are rocking along with overnight temps in the 30's, then you have a cold front that drops the overnight temps into the single digits and the day time temps in the 30's and my OWB doubles consumption, or at least so it seems. So, to track this provides some realiable data that can at least give us a reasonable benchmark of usage. Of course we all have the variables of home construction, wood speicies, and wives to consider.
-
Good points. Don't forget your elevation is a factor too! You running with or without restrictor plate?
-
The stove shouldn't know that it's colder unless it just never completely seals off. Its not rocket science. Wood has a btu per pound rating and the colder it is outside the more btu's your going to have to make.
Now you could see very slight differences based on a cleaner firebox and such but I think your research could be taken a step farther. How about weighing your wood each day and recording the number of pounds of wood your putting in your stove, and if you have a moisture meter use it and record that as well. Recording it in terms of "pieces" is a very broad term because they vary greatly in shape/weight/moisture and that all changes. So to get down to some harder data take a scale out and weigh your wood. Ill do it too! I'll start doing it when I quit burning this junk I am now, well be able go tell a lot more about the data when we get it down to a pound.
-
Point well taken. I can weigh my wood the next couple days and check moisture, but only on the ends. I recently provided my moisture content report at another post recently.
I should point out my wood is 95% oak. Maybe I should of mentioned that before we got this far.
In any case- Game On!!
-
Ridge kid, I just read my post and I was like, "it sounds like I'm challenging him to a duel" haha not the case
I was trying to say if your going to do this amount of work in this stuff,weighing the wood would give us a lot more valuable info. We know what btu per pound that wood is, well research to see what % moisture content affects that, I'm sure wilie has some numbers. But it will take your research to the next level.
Burning oak, oak in general should average about 25 million btu per cord. White oak according to most is around 26.5 and your other oaks are around 23-25, so 25 million or there about. Hickory is the best you'd have access to and it's right around 30 million btu per cord.
-
Those are good numbers. Can you break that down to BTU per pound?
Wish I had more time for this but two days is about I can do this weekend. Hopefully that can give us a idea of what's really going on.
-
I'd like to do it over the course of 2 months, Jan and feb.
Yes wood is 8660 btu per pound at 0% moisture content.
So if you have 20% moisture content, So if you had 1.25 pounds of wood at 20% you have about 1/4 pound of water and 1 pound of wood. So, at 20% moisture content the available btu is around 6930 or so.
-
Also keep in mind that wood is wood. Oak, pine, walnut, hickory, elm, apple hickory, Osage orange, no matter what wood it is! It's still wood! The only thing that changes is the density of the wood, better firewood weighs more because it has more fiber.
For example: A cord of seasoned white oak is around 3700 pounds, a cord of Cedar is only around 2000 pound. Each contains the same number of btu per pound, but the denser wood has more btu.
Live oak is supposedly the best firewood but only grows out west, it's 4880 pound per cord dry or almost 37 million btu per cord
Osage orange is the best in the eastern parts at 4700 pounds a cord or around 33 million btu per cord
-
http://hearth.com/econtent/index.php/articles/heating_value_wood (http://hearth.com/econtent/index.php/articles/heating_value_wood)
-
http://hearth.com/econtent/index.php/articles/heating_value_wood (http://hearth.com/econtent/index.php/articles/heating_value_wood)
quite interesting always thought red oak better than white oak and both better than apple because of how it feels after dried. red oak always seemed heavier after it was dried. never weighed on scales nor compared moisture content. maybe it takes red oak longer to dry out which makes it feel heavier.
Ridgekid keep up the good work,your data will be helpful to OWB owners. :thumbup:
I think scott is right on, going by weight would give more realistic data of wood consumption.
-
Morning all,
I had a friend give me about 1/3 cord of black locust in early February of last year. It had been seasoned for a little over 2 years. That species gives off a lot of heat! I've never burned anything that burned so long and hot. None of the locust species are on Willies list.
I read somewhere that there a few exotic species whose BTU content is a little over 9000. If I remember there are a few that are right around the 8000 mark also.
My uncle retired from Dow Chemical as a chemist. We were talking about BTU's and such a few years ago and he made this comment:"If I were dried down to 20%, I'd give off about the same amount of BTU's/pound as a gnarly old swamp oak. In fact, most any carbon based life form will".
Not to gross anyone out or anything, but I've gasified a couple different animal species in my Empyre 100 last winter. Free heat- no smoke! That's how us northern rednecks roll sometimes.
Marty
-
Black locust from what I've read from different sources is 27-28 million btu per cord
-
Check out "chimney sweep online" they have a good reference.Maybe someone could post it up. I am not that good with comp.
-
Good points. Don't forget your elevation is a factor too! You running with or without restrictor plate?
Yes, the restrictor plate is in, but with temps in the single digits, it doesn't seem to be restricting much :o
-
I'd like to do it over the course of 2 months, Jan and feb.
Yes wood is 8660 btu per pound at 0% moisture content.
So if you have 20% moisture content, So if you had 1.25 pounds of wood at 20% you have about 1/4 pound of water and 1 pound of wood. So, at 20% moisture content the available btu is around 6930 or so.
TWO MONTHS!! I can't do that. Here's a compromise-
I do count how many pieces I put in the OWB. After this weekend, we average the weight of what I stock and multiply it by the number of pieces I throw in?
For example:
Today I stocked 5 pieces (so far)- The weights came in at 11#, 12#, 12#, 17# and 21#. They all had a 16% moisture content.
The average weight of those 5 pieces is 14.6#.
If I multiply 14.6 by the total number pieces used so far this year = 5007.8#
Based on that information- How many BTU do you calculate I used in 44 days of operation?
-
Based on this figures and let's say your wood averages 20% moisture per stick that equals are 34.7 million btu's
Thats assuming your getting about 6930 btu per pound, which would be great.
Now you could do a calculation on how many btu your home Requires and how many of those btu u r using and losing.
-
2700 sq ft in my zone of the country requires 121,500 BTU to heat my house. My 50 gallon hwh is holding water from the dhwx which comes in at 57* water and heating it to at least 160*. Based on that I use 41,200 BTU.
I have no real way to figure how many times I drew heat off the Green Dragon to maintain that comfort zone. Do you have a educated guess?
-
I have no way of knowing that but I'll try to pull some numbers together from all of this.
-
Avg weight changed to 15.6#. I added four pieces to keep her going for the night.
I'll weigh all my pieces tomorrow too and come up with final number I can use with my wood count. I just have to keep the bathroom scale hidden for one more day! :bash: Btw it's digital.
-
Added five more pieces this morning changing the avg weight to 13#. On a side note: I walked back in the house and my wife is roflhao. What's so funny? I seen you out there weighing your wood! :bag: I guess it would look funny if you didn't know why.
-
Haha. I can imagine
-
Final stocking for the weekend. I put in 19 pieces of wood weighing a total of 237#'s . This averaged my pieces to 12.4#'s each.
I'll keep up my wood count and use 12.5#'s per piece. Sound fair?
-
Scott-
Using your number 6930 btu per pound I went and figured a daily average.
If I used a average of 118# per day over the weekend I came up with 817,740 BTU per day? or we can look at it like this: 125,806 BTU per burn? (I had 6.5 burns per day-13 total for the weekend)
I already figured it takes 162,700 BTU to heat my water and home. I still can't tell you how may times I used HW or the heat came on. If I take 162,700 and divide it by daily total BTU it equals 5X. Since I recorded 6 burns my loss would be one burn or 125,806 BTU's? Of course this could be misleading too since the Green Dragon does not come on every time my heat or HW gets used.
I don't know, I'm just trying to get a clearer picture of what is actually going on. What are you thoughts?
-
I'll try to figure something up..
Now as far as what you need to heat your home, the btu calcs usually base it off the coldest weather we should see, is that correct?
-
Yes.
The multiplier was 45-50 x sq ft. I used 45 Because my home is well insulated.
-
Yea so, so far this winter the actual heat load has been like 1/3 of what it will be when old man winter arrives.
Seeing that you haven't burnt in really cold weather yet makes me think you'll be in for a surprise before long. I don't mean that in a bad or negative way but when you get to single digits and less wood consumption really goes up.
-
Well....
Lets say your heat exchanger in your furnace is a 100k btu....
Let's assume that it kicks on 20 times per day for 10 minutes each time... Assumption only...
200 minutes or 3 1/3 hours, which would give you 333,000btu in your home...
Your saying 42000 btu for your hot water. That gives us 375,000btu that your using..
We have already determined you Could be producing around 800,000btu per day...
Sooooo... At this rate 46% of the heat your producing actually ends up being used and the rest is wasted somewhere in the cycle and up the stack...
You were dividing total btu's of wood put in, or available btu's, and dividing it by # of burns, that would be assuming 100% efficiency, and well, it's just not how we should look at this
Now, earlier before I did the math I said in this winter were likely using 1/3 or so as much wood as we soon will. You were you needed 162kbtu per hour for your home but right now your only using about 16k btu per hour on average, in weather like we've been having it doesn't take a lot and I think from what I'm gathering your home is very well insulated and even in the coldest conditions your home won't require near as much as you think....
I'll be back after more calculations
-
Ridge, your saying you need 162k btu, are you thinking per day or what? Because, it never made sense.
Most homes use 25k btu per day heating water, you assume 40 and that's probably right! So, based on all calculations I can find a 2700 sq ft well insulated home in your area should require Between 32,000 and 65,000 btu per hour during the winter...
Now the math is making sense'
I had already guessed we were at 1/3 winter load. And that you were using 15k btu per hour, we know that, so the math makes sense that your only using 15k per day but could be as high as 65k btu this winter, average winter conditions would require about 45k btu which is my thoughts, and makes my 1/3 load, 1/3 of 45000, which is 15000 and that's exactly what your burning now...
I feel these numbers are actually pretty close to reality
-
Hey Ridge-
You know how I don't always agree with Scott, but he's right this time around. The difference between upper 20's at night and upper 30's during the day and single digits at night and teens during the day is like..well..night and day- especially if there are high winds involved. If your wood consumption ends up being anything like mine, you'll be going through between 2 and 3 times what you are burning now. I've went through a full cord in 25 days before, and thats with a 1700-1800 sq.ft. home and a gasser.
On a positive note, though, the petroleum institute won't get a dime from you no matter how frigid it is outside. That satisfaction makes all the hauling, splitting and stacking well worth it.
I really am impressed with your live stats. I've not been able to check on them and see your blower running yet. That is certainly a good sign.
-
This makes me feel a little better. As I write this, the outside temp is -12 degrees and we had -3 degrees last night. The high today was 13 degrees. Last night I topped off my CB5036 around 10 pm and it was around 157 this morning at 6:30 and puffing with mostly ash left over. I refilled it and left for the day. Just got back in at 7:00pm and it again was mostly white ash. I filled it again and will let you know what it's like in the morning. BTW, this is not a total fill, but about 2/3rds full. 90% of what I am burning right now is aspen, with 10% pine. Anyway, I recognize that aspen doesn't have the BTU's that hickory or oak has, but I am surprised about how much wood my OWB is burning with the restrictor plate in place. Having said that, we have been having some cold spells that really suck the wood down.
-
wow minus 12..here in ontario canada we are having rain and today was about 40..tomorrow calls for 32 (0 in canada) for a high temp and staying firgt about there for 24 hours
-
Scott-
Your assumption of a 100K BTU HX was right on.
162, 700 BTU was just a general number by adding my home requirements. (HX and DHWX) And that's if they operated at the same time, every time.
I don't disagree with any of your calculations.
I think my calculations were high. Here's why.
The green dragon only holds 196 gallons of water. (Plus what ever 230 ft of pex, a 100k BTU HX and 20 plate hold)
My burns only last 15 minutes. So with 6.5 burns that's only 1 hour and 37 minutes.
Out of the 118# I stocked Sunday, half took me into Monday (Today) until 7PM, 24 hours after I stocked it.
Recalculating, I think it was closer to 408,870 BTU produced Sunday. (62,903 BTU per burn).
Going back to your estimate I used 375,000 BTU (Which again, I agree with) With my recalculation, We could say I used 91.5% of the heat created and 8.5% is loss or went up the stack. I know what you (and others) are thinking-NO WAY. I have doubt it's that efficient too, compared to gasifiers.
What I do know is that I burned 1 cord of wood (as of this evening) in 47 days of operation. I can't believe 54% of that wood went up the stack! (sorry~)
There's got to be a better way to calculate this!
-
from what i read about these stoves, a non gasser is at best 60 percent efficient (or less)
-
Scott-
Your assumption of a 100K BTU HX was right on.
162, 700 BTU was just a general number by adding my home requirements. (HX and DHWX) And that's if they operated at the same time, every time.
I don't disagree with any of your calculations.
I think my calculations were high. Here's why.
The green dragon only holds 196 gallons of water. (Plus what ever 230 ft of pex, a 100k BTU HX and 20 plate hold)
Hey RidgeKid, do you have a cap on your stack, and if so, would that make a difference in efficiency?
My burns only last 15 minutes. So with 6.5 burns that's only 1 hour and 37 minutes.
Out of the 118# I stocked Sunday, half took me into Monday (Today) until 7PM, 24 hours after I stocked it.
Recalculating, I think it was closer to 408,870 BTU produced Sunday. (62,903 BTU per burn).
Going back to your estimate I used 375,000 BTU (Which again, I agree with) With my recalculation, We could say I used 91.5% of the heat created and 8.5% is loss or went up the stack. I know what you (and others) are thinking-NO WAY. I have doubt it's that efficient too, compared to gasifiers.
What I do know is that I burned 1 cord of wood (as of this evening) in 47 days of operation. I can't believe 54% of that wood went up the stack! (sorry~)
There's got to be a better way to calculate this!
-
Yea ridge, I think the btu calculation was spot on. Because it does not matter how many times the stove cycles at all. That does not change the btu amount you placed in the stove whatsoever. Also you cant really calculate it by the # of btu created per burn because quite frankly it just doesn't work that way.
So in my opinion, your # of cycles is irrelevant and so is water capacity. Were weighing wood and seeing and estimating how many minutes your fan ran over your known btu rating coil.
With all respect ridge, the % of 46% fell right in line with every other test I've seen from cb or a similar designed unit. For example natures comfort non-gassers were at 75 percent eff with a test we now know was off at least 20-25%.
Your pound usage was right in line per 24 hour and everything, the math kinda fell into place. Keep in mind ridge it's much cooler now than it was the first few weeks we were burning when it took only 4-6 pieces per 24 hours or less
-
wow minus 12..here in ontario canada we are having rain and today was about 40..tomorrow calls for 32 (0 in canada) for a high temp and staying firgt about there for 24 hours
Yea, the actual low at my house last night was -14 degrees. We live at 8600' in the mountains of Colorado. My OWB was out of wood this morning at 5:30. During these cold nights, my OWB undershoots the 175 temp setting by about 8 degrees to 167 or so when it is burning. Have you noticed that your's does that with below zero temperatures? I have infloor heat and all my pumps are running in the house with the heat demand.
-
Oh and in regards to 91%, no gasser is getting that either. The folks at Garn who have one heck of a gasser say real world numbers in there units is in the low 80's. They burn over 2000 degrees
As far as a better way of calculating it, there is only one way. Weighing your wood over 24 hours and figuring how many minutes your coil ran. The hot water part isn't a big player and your estimate of 40k is fine.
If you think you can get over 55% eff with a natural draft unit, well, IMO you have the best one ever produced.
If it makes you feel any better I crunched some numbers last night on my cousins hardy and only came up with 41% eff, he has some install issues to i think
-
Scott-
I believe you. In fact it couldn't be 91%. Let's remember it takes 1 btu to raise 1 gallon of water 1*. Which means on my 15 minute burns to raise 200 gallons of water 10* should be approx 16,000 btu each, right? So I actually made 104,000 BTU in 6.5 burns? I guess that don't make sense either If I used 375,000 BTU. :bash:
Oh the drama! I will continue "counting" my wood estimating an avg of 12.5#'s per piece and maybe we can narrow this down.
The real test is forthcoming: http://www.anythingweather.com/current.aspx?id=48442 (http://www.anythingweather.com/current.aspx?id=48442)
Oh BTW- I like Willies estimate of 60%. (or less) :thumbup:
If we continue to work on this I think as time passes we might just narrow this down. I could start doing email pushes for when my air handler comes on. I won't be able to time it, but I would know how many times it did come on???
-
Pardon the neophite question, but what is a "burn"?
-
Every time the green dragon comes on to reheat water. = burn
-
Ridge, I urge You to continue but your not allowing for how many btu roar up the stack during a burn and there is just so many variables for heat loss not considered..
If you think we can ever skew the numbers enough to get your furnace to 60% eff we might be wasting out time. It's just really hard to get to numbers that high, just be rest assured that whatever your getting is that much the power company don't get.
As far as your stove,
Im not knocking it one bit, there a very good unit, I just don't think the eff is anywhere near what your hoping to see. In talking to other folks as well, they say that cb eff rating is between 46-54%.
-
Was thinking that is what you meant, but how do you monitor that statistic?
-
Every time sensor 3 falls below setpoint it pushes a email!!!
Btw. Email pushes do not work on ssl servers. I got a free non ssl email address at gmx.com just for my temp monitor.
-
Scott-
Don't be so defensive. I'm a noobie! If you, or Willie or Yoder say it's not as efficient as 60% who am I to argue?? I don't know how to express my tone in writing here. I just want to let you know I am enjoying this. I am not intending to frustrate anyone. I just want to UNDERSTAND what my OWB is doing.
I am, and will, continue to count my wood until the last fire in the spring. Then I can tally it all up. We might not be any closer on figuring how many btu's I generated to how many were used, but I'll know how much wood I used, what the avg temp of the day was and how much electric I saved. OH, and as of Nov 22nd I'll know how many times I went into a burn cycle. Most people on here probably just throw wood in their OWB and forget it. I want to learn from mine. So when there is a problem I can say without a doubt how it ran before the "problem" occurred.
Thanks for your inputs!!
-
ridge, i cant say for sure how efficent these things are i only report on what i read. It is (ibelieve) likley close to 60 or less as (if it is true) that gassers burn 25 to 30 percent less wood than our old styles and they claim to be 85 to 90 percent efficient?
for my own place here in ontario it is said an average home here should normally use about 100,000,000 btu per season
i burnt last year about (not true measurments but figuring what my trailer holds) 12 cords. this equates (according to charts off the net) a usable btu count of 163,800,000 btu and 60% of that number is very close to 98,000,000
and i also heat my domestic water so perhaps my home is a little better than average or (i do live in the southern part of ontario) my location puts me in the low end of btu users?
i know its not a true and good measurment of my stove but it likley is in the ball park?
-
Ridge, I'm not really being defensive buddy.. I just type as I think and never realize how it sounds til I read it back to myself. haha
-
Yea willie according to what your saying the math adds up...
-
We are cooking now!
Yesterday we had a Avg temp of 34.7*, added 10 pieces of wood and had 12 burns. Got a little snow too!
Burn baby burn! >:D
-
34.7.. Ridge just wait til the daily avg is 14.7 and the wind is whistling! It's crazy how much wood consumption goes up when it gets down in single digits! You'll still love every second of it cause you'll be as snug as a bug in a rug and the meter won't be spinning any faster lol
-
We'll dip pretty low at night around here, don't recall a daily average that low since 1994. (*knock on wood*)
And yes. The meter is moving pretty slow. We received some digital meters earlier this year so I can't watch the disc fly anymore. I did purchase a Black and Decker monitor that "looks" at the optical eye and transmits it's current use INSIDE the house.
I'm getting lazy huh????
-
94, my dad has that written on the calendar. -17 , -37 , -23.. 3 nights in a row! It was crazy, I was taking buckets of water out of our garage and pouring it out on stuff to just watch it freeze!
What kinda lows do you see in the winter ridge? Every year we usually have 6-8 nights below zero. It's usually 10 degrees colder in my area vs being in a city only 30 miles away.
-
This is pretty close. Being in the mountains 15 miles west of Homer City we can run about 5* less in temps and x2 on the snowfall.
http://pics2.city-data.com/w1q/lhaq22689.png (http://pics2.city-data.com/w1q/lhaq22689.png)
http://pics2.city-data.com/w5q/snwq22689.png (http://pics2.city-data.com/w5q/snwq22689.png)
BTW- I missed that winter of 94' I was in Indonesia banging on the thermostat trying to get the AC unit to kick on!!
-
I clicked on to your pictures and it says 403 forbidden.
-
Try this instead:
http://www.homefacts.com/weather/Pennsylvania/Indiana-County/Homer-City.html (http://www.homefacts.com/weather/Pennsylvania/Indiana-County/Homer-City.html)
-
The green dragon got her first real test at 16*. At 9pm I put 8 pieces of wood in her. There were a few pieces left from the day. At 9am this morning I saw her come on but not smoking. Oh oh we must of ran out of wood. So I threw on some clothes and head out. Open the door and there is a raging fire with at least four pieces left!!!
So I checked my email alerts and found out she burned 7x since midnight. 8x since the stocking last night at 9pm.
Overall I couldn't be happier!!!
-
I dont want to sound stupid but how do you all know how many burn cycles you have on your boiler mine is a CB5036 ???
-
You have some reading to catch up with.....
http://outdoorwoodfurnaceinfo.com/forum/index.php?topic=1286.0 (http://outdoorwoodfurnaceinfo.com/forum/index.php?topic=1286.0)
Welcome to the site!
-
You have some reading to catch up with.....
http://outdoorwoodfurnaceinfo.com/forum/index.php?topic=1286.0 (http://outdoorwoodfurnaceinfo.com/forum/index.php?topic=1286.0)
Welcome to the site!
You have to be one of the politest individuals I've ever ran across. And patient...especially where I'm concerned!
-
PWdiver,
We have some serious experimentation going on with the CB5036. RidgeKid along with others have put some real-time monitoring equipment on their units. Not only that, there is a group in this forum who are actually weighing their wood before loading so they can provide all of us with some pretty spectacular real life information to help all of us understand how we can optimize our units.
Happy reading!
-
I heard Ridgekid is asking Santa for his own set of bathroom scales for Christmas so his wife can have her's back in the house. :thumbup:
-
You guys are too funny!!!
I hope your all paying attention. I'm only doing this since it's my first winter with a OWB. Once I get my numbers I'll be set for the winters to come.
-
Thanks for the info, I have really enjoyed our boiler the Wife was alway's complaining about how cold the house was now she can have it as hot as she like's. Monly problem is with the door it appears to be bowed at the top & on side where the handel is, It will get real hot sometimes 212 sounds like a tea pot. Im still working with my dealer about this issue. But thanks again interesting stuff. :)