Garn wood usage

djblech said:

This is for current Garn users. How much wood are you using per year. The web site estimated about 8 cord per year, I was wondering if that was accurate.
Thanks
Doug

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Doug,

I'm really new to garn wood usage, only been online for 1 month. My first impression though, I'm burning more than I expected. I still have some boiler room insulation to complete, but I not sure it will change the burn rate much. So far I'm not getting the "one wheel borrow / day" you see in the garn video. ;-(

I think 8 cords / year is a huge generalization. I estimated my wood needs based on previous year's oil usage times efficiency of my oil boiler, and converted that to BTU's. I then took that BTU number, converted it to cords of Oak, and applied a 75% efficiency conversion by the GARN. My result was approximately 15 Full cords / year. That is entire year, since I used heat my DWH with oil, now wood. So Far I have been online for 1 month today, and we have used 4 cords. I have to say the past month had a number of "Heating Design Days", so we were will below normal in terms of temp and wind. I feel that definitely added to my burn rate. My gut feeling is I will be around that 15 cord number, plus or minus 2 given my wood is not all oak.

I don't have a Garn, but that seems like an awful lot of wood from something that's a highly respected gasifier, especially down in Pennsylvania. I have a Tarm Solo 30 up here in Maine heating a 2,500 sq. ft. house and keeping 1500 sq. ft. in the basement quite warm as well, and supplying DHW on somewhere around 5 cords of good hardwood a year.

Rory said:

I don't have a Garn, but that seems like an awful lot of wood from something that's a highly respected gasifier, especially down in Pennsylvania. I have a Tarm Solo 30 up here in Maine heating a 2,500 sq. ft. house and keeping 1500 sq. ft. in the basement quite warm as well, and supplying DHW on somewhere around 5 cords of good hardwood a year.

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Highly respected or not...facts are facts. I burnt a lot of #2 diesel BTUs for 10 years prior to now heating my home and outbuilding. My house consumed roughly 2000 gallons/year. The math to convert to cords is left as a homework problem, but my numbers say something like 12 cords. So far my gut feeling is I am tracking the BTU consumption. I do believe I have a couple of things left to improve perfromance. I have only operated my GARN unit for exactly 1 month today, so my data is very preliminary for the GARN performance. My wood so far has not been the best "good hardwood" fuel. Mostly some "punky" oak,apple, and some ash. Time will tell, but trust me I want to extract as much as I can out of my GARN

Well, if you're replacing 2,000 gallons, that makes sense. We used to use around 1,000 in my house. We burn a very small amount of propane in a living room heater, and my oil burner is hooked up as a backup, but runs very little.

Honestly, something doesn't seem right. 10 cords is huge. I have 2200 sq. ft with 9' walls and used about 1 1/2 cords since Nov. 28. I have a very well insulated house though. I'm surprised Garns are rated @ 75% efficiency. With that money I'd expect more. Garn might be totally honest with the efficiency though when other may be stretching it a bit. Chances are though it will outlast my Eko 25.

ihookem said:

Honestly, something doesn't seem right. 10 cords is huge. I have 2200 sq. ft with 9' walls and used about 1 1/2 cords since Nov. 28. I have a very well insulated house though. I'm surprised Garns are rated @ 75% efficiency. With that money I'd expect more. Garn might be totally honest with the efficiency though when other may be stretching it a bit. Chances are though it will outlast my Eko 25.

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Basing one's wood consumption on what someone else's may be is an exercise in futility. There are way too many variables in structures and firewood alone to render any anecdotal evidence invalid. As an example, I have one kid running a Garn in a new 5500 sq ft house and another kid running an Econoburn 150 with storage in an older farm house half that size. The one with the EBW150 uses more wood by quite a stretch. Does that mean the Econoburn is less efficient? Not from what I have seen. The difference is in the structure and the fact that the kid with the Garn has his wood seasoned at least a year and a half while the other one has wood seasoned only 3-4 months.

Garn publishes their efficiency rating based on the lower heating value of the fuel which yields lower and probably more realistic results. If you read through literature on European boilers burning gas, oil, wood or whatever, you'll see that some are rated over 100%. (which produces a whaaaa....? moment) Those are high heat value numbers that are derived by calculating latent heat from the phase change (liquid to vapor and vapor to liquid ) into the equation. I do not know this to be a fact but have heard that the Euro boilers use the high heat equation to generate their numbers. I'm just saying that one should always take ratings with a grain of salt and a healthy dose of skepticism until facts are proven.

PS:
One thing I can say with absolute surety is that of the two boys, the one with the Garn spends far less time tending fire than the one with the Econoburn. Total of 15 minutes per day vs an hour or more.

Lets try to keep it simple. I was burning about 1000 gals of oil a yr. i was told, by the guys on this site, that a gassification boiler( or garn) 1 cord of seasoned wood= 150 gals of oil. It's about spot on. I also was told by guys on this site that, after a yr of learning to use the boiler, might be able to stretch it to 1 cord = 175gals. Still spot on! if you're not burning oil, convert the figures. K.I.S.S
BTW.. 4 cord seems like alot of wood, but............... I'm not in your house. WAY TOO many variables on how much wood I burn compared to someone elses house, can't compare square footages!

I built my own "garn"like boiler and have had it online since November 11 (middle of 10th week of heating). Looking at my wood usage to date, I will probably use 6-7 bush cords of wood/ year. I typically use about 1/2 stove wood cord per week (18-20 - inches long x 48-inches x 48-inches per week). I heat a 2300 SF well insulated house plus 2000 SF basement all at 70 degrees or better with in floor heat, heat all my DHW and keep the shop that the "garn"like boilers is in (24'x24'x12 foot ) at 40-50 degress. There are 5 in the family and lots of showers. I have not used 1 drop of propane since November 11. In a typical year including hot water, I would use approximately 1300-1400 gallons of propane per year. Right now, I fire every other day unless it is -15 below F and then I can still go 48 hours but the house temp starts to drop a little as I need warmer water then 125 degrees. My house is in a wide open field and in constant wind in the Easter U.P. of MI so we do get cold temperatures. My boiler is almost 3000 gallons so that gives me lots of flexibility as to when I fire it. I know I need to tweek a few things and I feel I can do better on efficientcy, but overall I'm very pleased with the performance. I only have a fire burning 15% of the time and even then I don't have anything other then white smoke/steam. I plan to add a tubilator in my last pass and add some controls next year. My wood has only seasoned over the summer so far, but that will be mosly corrected by next year as I have enough wood cut and split for more then half of next years heating season drying since last spring.

Just following the thread and have a question. How much does a gallon of oil cost? Then I can compare with my heating.

Thanks

the garn its self is a pretty steady state reliable appliance, and a AVERAGE, at the end of the burn effiency of 75% is probably not far off, i have recorded mostly 82-86% during 3/4 of the burn cycle. I suspect the better downdrafters under load will do the same, keep in mind the garns firing rate is usally twice of most downdrafters, the only equalizer they share would be the standby losses of the garn and the standby cycling of the downdrafter, and that is eliminated by storage. So it really comes down to your heatload that is comprised of more variables than the combustion effiency of either design boiler. Just some quick info on my last week, 14 burns with the garn in n/w ct. total burn time 36 hrs 42 minutes= 5.24hrs/day total btus consumed by demand 7,880,000= 1,125,714btu/day=a ave heatloss of 46,904btu/hr. Gallon movement through garn=82,120=11,734gpday, based on a wood loop pump rate of 13gpm , the circ ran 15.04hrs/day. more info could be had from this, just quick data.

Just some observations.................

I started burning full time in mine as soon as it was plumbed up, with zero insulation. As time has permitted, I have worked on closing it in and insulating little by little. Other than a week vacation, my oil burner has been shut off since 10/16/09. Calculating from carefully kept, accurate oil consumption records (10 years worth) and using btu's/cord figures for better than average mixed hardwood, we anticipated using 12 cord for a calendar year (includes dhw in summer).

It is still not completely insulated and closed in as tight as it will be. I have 30-40 feet of exposed pipe in an unheated building. I am keeping my oil boiler hot with the garn. big no-no. I 'm running the garn pumps off of the aqua-stat on the oil boiler and am running only 150 degree water in the distribution system (lot of cast iron and radiant floor).

Each time I insulate another part, wood consumption drops, substantially. More than you might think. So far, as near as I can tell, I've used between 5 and 6 cords.

Also, big difference in wood type. I have red maple and red oak mixed. I burn it as it comes. When I get to a point in the stack where it's all red oak, WOW Huge difference.

So, at this point, I'm thinking that the garn is a magic machine at transferring heat energy from wood to water. But it won't make wood or overcome system design flaws or finish the install..............................(piece of crap :roll: )

Rick Stanley said:

So, at this point, I'm thinking that the garn is a magic machine at transferring heat energy from wood to water. But it won't make wood or overcome system design flaws or finish the install..............................(piece of crap :roll: )

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:lol: Too funny Rick. My POS GARN won't split or stack my wood either . . .

My last full year burning oil ('07-'08) I used 1200+ gallons of oil. My wood supply is a menagerie of different species, condition, and configuration. I have not really tried to calculate an accurate wood volume usage figure due to those variables. However, over the last month of very cold weather, we have been very comfortable burning two loads a day, with a burn time of ~2 hours per load. This is to heat our 3k sq. ft early 19th c. farmhouse, AND keeping my 900 sq. ft. uninsulated garage at 45+ degrees. A "wheel barrow" load per day is just about right for us. During this past cold spell I would burn roughly 1/3+ of a cord per week on average, so about 1-1/3 cords per month when temps are low teens at night and low 20s during the day. Now that temps have risen to upper 20s at night and upper 30s during the day, I will use about half that much. Jan-Feb is our coldest period.

If I were to estimate my average wood usage based on this years' pattern, I would estimate 7-10 cords will be my needs for '09-'10.

HAhaha. The funny thing is we all spent big time bucks to go cut wood.

I'm praying I'm under 10 cords. If my neighbor with his OWB heats his with 10 cords, I'll feel dumb if I can't do it for that.

I average about 2k gallons a year. I'm banking on 25% of that is waste because of the old system. 7-8 cords I'm hoping will do an average year. The goal will be to lower that number to 4-5 cord with radiant/more insulation.