Here's the start of what i will be building this winter. My central boiler is old, tired, and needs to be retired! I am dealing with heating a 5100 sft house which once was a school. the majority of the house is made of cinder blocks and has 13 ft tall ceillings. It definatly was not created with the intent of being effecent! It has a nice cold slab the entire 5100 sft of it. With all this being said my centrsl boiler saved me about $5-800 dollars per month for the heat and hot water. However i fill it twice a day and it is real fill ups!Th CB takes a 5' log and it is a hugry beast. I ve been starting to look at different gasification models and realized that i wanted lots of storage not 50 gallons of water like the majority of the the gasification boilers out there. I soon realized that i will be building this one myself. Having welded/repaired half a dozen wood boilers for friends and family has given me different ideas of how i want this to be built.. for now heres a pic of the tank that were starting out with.
18' long wood boiler!
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Welcomde to the forum fab-master. Will your project be a gasifier with lots of storage built-in? The tank you have looks lrge enough to have a gasifier on each end with storage in the middle. You really need to be a fab master.
Well this thread came to mind when I saw your tank.
https://www.hearth.com/econtent/index.php/forums/viewthread/11262/
https://www.hearth.com/econtent/index.php/forums/viewthread/11262/
Mike I think your right on as far as the principle goes... however i want to try a couple things different so all suggestion are listened to. To be honest I was looking at getting the garn unit, however i think the 1500 gallons that it has to offer wouldn't have met my btu requirements per day, since i may not always be around to build additional fires durring the day. I am looking at building something that will give me at least a full 24 hour btu storage capacity in the very coldest days of winter and more days when it is above the 30's...
Just so you know, Garn's coming bigger as well....2000 gallons is typically, and I think there is a 3200 gallon...though maybe that number is wrong on the top end. I'm sure they are not cheap though....Good luck! You get to walk inside the tank when welding for sure!
heaterman
Minister of Fire
bpirger said:
Last I knew there was a 3200 available at the factory for a really good price.........for a 3200 that is.
The other thing you could do is leave that tank be a tank and just connect a normal Garn to it. An 8 hour burn would put around 2.5-3MMbtu into the system.
5100 sq ft @ a normal old building heat loss of 35btu/sq ft would be about 180,000 per hour.
2.5MMbtu in storage would equate to around 14 hours of heat.
ok just looked at garns site it looks like they have different sizes and like you guys mentioned as big as 3200 gallons! There is nobody in my area that has one of these and i was misinformed thinking it was more like one size.. heater man can you pm me the price for just the unit on that 3200 your talking about. I already have the rest of my set up installed from my existing outdoor unit.
Also for the guys that have built these, why not run the air intake pipe through the fire box to really preheat the air? I am thinking of running two air intake pipes from the back of the unit, then run them inside the firebox on the right and left side all the way to the front collar where it will be introduced into the fire at much higher temps than what the water alone could heat the pipe to..
If you do that with the intake pipes you probably don't want to run them into the collar then. My unit @1hr into the burn will get the collar up to 350-400*F. That can really heat up the room. The expansion of the collar is enough right now at this temp swing now double it? I think thats why the door sealing flanges are flat and the door lock mechanism is designed the way it is. Also I would wonder if the pipes would last very long.
My uncles is built out of a tank like that. It was a 3000 gal fuel tank. turned out to 2740 gal storage.
My uncles is built out of a tank like that. It was a 3000 gal fuel tank. turned out to 2740 gal storage.
jebatty
Minister of Fire
heaterman said:
Last winter I ran a fairly exhaustive test burn on the Garn WHS3200 in a real world operating environment, and last month I was able to more accurately calculate the btuH output of the Garn, subject to the one remaining variable of actual moisture content (assumed was 20%). In short, this Garn maintained a sustained output of 435,000 btuH over a 19 hour burn period, which equates to about 3.5 MMbtu to the system over an 8 hour period, assuming no losses. Garn WHS3200
But be careful in equating btu's into the system with btu's in storage, as "effective storage" relates to the minimum temperature of water that your system needs, the gallons in storage, and the delta-T of the storage available. For example, if your minimum needed temperature is 160F and the maximum that your storage can be heated is 180F, and if you need 2.5MMbth in storage, you would need 15,000 gallons of storage. But if your minimum needed temperature is 120F and storage can be heated to 180F, then you would need "only" 5000 gallons of storage.
With regard to the Garn, be aware that the Garn is not pressurized and a heat exchanger will be needed if your system is pressurized, that a hx reduces maximum available output temperature (assumed about 10F reduction generally), and that Garn advised Deep Portage that its most efficient operating range is at output temperatures of 140F and lower. You will want to consider this if your system requires higher temperature water. An alternative would be a boiler like the Wood Gun or other pressurized gasification boiler, with additional storage to meet your needs.
Ok, gathering parts and such.. I have a few steel yards near me that appear to have everything that i would need. One question about the firebox though, would there be a disadvantage by using a square firebox vs a round one? I believe i read somewhere that its not good for some reason...
what about the pipe sizing? For the heat ex. passes they have either 4" or 6" available in different thicknesses. it looks like most of the stuff there is probably close to about a 1/8" what thickness did you guys use? As for the intake I am leaning towards a 8" due to the unit being so long.
heaterman
Minister of Fire
fab-master said:
Round is far stronger and less prone to warping than flat panels are. There is a reason our Navy's subs are round.
Besides, I like round. My wife told me I should get in shape........I responded that round was a shape.......just sayin.
heaterman
Minister of Fire
Thanks for the tip, Steve. Yea the garn 3200 is a little out of my range. having two side by side would be awesome! Although that would take up most of the tool crib room and clutter up my garage.
For now i think the build is going to start happening real soon. I am a part time machinist/fabricator, so projects do not scare me, although I have never made something this large. It will be something that i will build and design as i go. I don't have any plans and have never seen a Garn nor do i have any one near with a garn to copy from. However it seems to me that most of the people on the board that have built these have had a real garn to look at and have had time to study them up close which is why some of them are so similar in appearance. Mine will have the same basic principals as a switer/garn style boiler but i hope i don't disappoint people when it may not look like a Garn in the end..
Attached is a pic of a couple walls we had demo'ed down in order to make room for the beast! My son is just as excited as I am..
For now i think the build is going to start happening real soon. I am a part time machinist/fabricator, so projects do not scare me, although I have never made something this large. It will be something that i will build and design as i go. I don't have any plans and have never seen a Garn nor do i have any one near with a garn to copy from. However it seems to me that most of the people on the board that have built these have had a real garn to look at and have had time to study them up close which is why some of them are so similar in appearance. Mine will have the same basic principals as a switer/garn style boiler but i hope i don't disappoint people when it may not look like a Garn in the end..
Attached is a pic of a couple walls we had demo'ed down in order to make room for the beast! My son is just as excited as I am..
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heaterman
Minister of Fire
Dealing with something that size........ I would guess that the most critical issue other than construction itself, is going to be matching the heat exchanger area with the output capacity of the "burner" or firebox.
I'm not an engineer but common sense tells me that if your firebox/combustion air will consume 250,000 btu's, a person would surely not want to put a 500,000 btu heat exchanger behind it. Flue temps will be too low, condensation will result and things will go down the crapper in a hurry. The reverse would also be true only the result would be wasting a ton of heat up the chimney.
Drew and I are going to be assisting with a Garn install for John Haling (www.sawmilljohn.com) over in Whitmore Lake when his 1500 comes in. I don't think that's too far from you. If you want to take a look at it I doubt that John would have a problem with it.
I'm not an engineer but common sense tells me that if your firebox/combustion air will consume 250,000 btu's, a person would surely not want to put a 500,000 btu heat exchanger behind it. Flue temps will be too low, condensation will result and things will go down the crapper in a hurry. The reverse would also be true only the result would be wasting a ton of heat up the chimney.
Drew and I are going to be assisting with a Garn install for John Haling (www.sawmilljohn.com) over in Whitmore Lake when his 1500 comes in. I don't think that's too far from you. If you want to take a look at it I doubt that John would have a problem with it.
jebatty
Minister of Fire
The Garn WHS3200 (and I assume other models) have a ceramic like material inside the hx tubes. This likely is very important as it allows the secondary burn to achieve very high temperatures while insulating the hx tube and the high interior surface heat from the much cooler boiler water. Without this design it seems that direct water contact with the hx tubes via the steel is little more than a glorified OWB, with all of the attendant creosote, condensation, and inefficient burn characteristics. The prior comment on matching hx transfer with the output capacity of the burn box fits here very well also.
The other gasifiers (Tarm, etc.) operate similarly, with a ceramic secondary burn chamber to produce the high heat/efficiency before passing the fully combusted flue gases through the firetubes.
The other gasifiers (Tarm, etc.) operate similarly, with a ceramic secondary burn chamber to produce the high heat/efficiency before passing the fully combusted flue gases through the firetubes.
heaterman
Minister of Fire
The combustion process should be isolated as much as possible from the heat transfer process. This is done so well in a Garn through the use of a negative pressure combustion chamber that allows 2 distinct airflows to entrain the smoke and combustible gases before it turns into creosote on the walls. If you look in a Garn you'll find very little "stuff" other than a dry residue on the combustion chamber walls as opposed to positive pressure gasifiers that will be coated with creosote and tar.
The only "thing" you want going into your heat exchanger is inert hot gas. The smoke, tars, combustible solids and gas should all be turned into heat by the time you hit the heat exchanger tubes.
Your old Central, and every other standard OWB for that matter, all have the combustion process going on in the same area as heat transfer. Good heat transfer can not, will not, and does not happen under those conditions.
The only "thing" you want going into your heat exchanger is inert hot gas. The smoke, tars, combustible solids and gas should all be turned into heat by the time you hit the heat exchanger tubes.
Your old Central, and every other standard OWB for that matter, all have the combustion process going on in the same area as heat transfer. Good heat transfer can not, will not, and does not happen under those conditions.
Thanks for the tips guys... Yes i understand about the ceramic.. i will probaly end up using 3, 12" pieces giving me a total of 36" on the secondary burn chamber. However I noticed that the Switer boiler runs the ceramic all the way to the back of the boiler.. Also i want the fire box to be 48" long by 36" wide this will be out of 3/6" rolled sheet. The door will probably be made square just to be different, but really since it should be easier to make.
finally started collecting parts last month for the boiler. However it probably will be another couple weeks until i finish a current welding project I am working on, and then i will start this one..
Ive got the firebox, it's Half of a 500 gallon propane tank. It's a total of 60" long which includes the cone end, its 37" wide and probably 3/8" thick. I am keeping the cone end, I will weld the 16" reaction chamber tube on the end of it. I also got the reaction chamber castings, it comes in 3 different sections. I also picked up some a53 4" sch40 piping. Should i make the last pass out of 6"? what about the air intake?
Ive got the firebox, it's Half of a 500 gallon propane tank. It's a total of 60" long which includes the cone end, its 37" wide and probably 3/8" thick. I am keeping the cone end, I will weld the 16" reaction chamber tube on the end of it. I also got the reaction chamber castings, it comes in 3 different sections. I also picked up some a53 4" sch40 piping. Should i make the last pass out of 6"? what about the air intake?
Gasifier
Minister of Fire
Good luck with your build. You have some work ahead of you. I am envious of your metal fabricating skills. I am not a metal worker, unfortunately. How long do you think it will take? Are you hoping to have it on-line for next heating season? Do you have your wood c/s/s for next year already? Your new gasser boiler will be different from your old boiler. It is going to like dryer wood.
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