Garn vs. Wood Gun

Jim K in PA said:

Gooserider said:

I agree, the electric water heater element would be far from an ideal backup, but earlier in the thread, we were told that electric was the only available utility, and that there was no plan to install propane or oil... Given that the only option listed was electric, I was trying to come up with a solution that used it in as sensible a way as possible...

(If it was my setup I'd consider either adding a small propane setup, or at least a gasoline generator so that I could run the Garn, with or without power (Plus some solar heaters for summer DHW), but I was working within the specified parameters)

Gooserider

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Did not intend to have my response be a criticism of your solution Goose. Sorry if I did so. Although not in the plan, Andrew may want to consider the propane option, as it is cost effective and the propane has an indefinate shelf life with no additives or maintenance necessary like an oil backup would. Since this was a discussion of backup options, the propane solution could still work with a loss of electric utility through a small backup generator to run the pumps and sensors.

Geez - we sure do get carried away spending everyone else's money, don't we? :lol:

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Yes we sure do... Frankly I'd probably go for the propane setup in any case since I seriously dislike cooking on an electric stove, but that is more a personal preference thing... (I also suspect that I wouldn't be all that into cooking on a wood stove either for that matter...)

I also wasn't taking your comment as a criticism, just explaining why I had come up with the idea...

Gooserider

Jim K in PA said:

Durango - in what way do you think the GARN is excessive? I don't want to put words in your mouth (or keyboard ;-) ). The GARN is not comparable to any other downdraft gassifier based on hourly Btu demand or output due to its integral storage. The GARN can easily put out 400K Btuh, which is more than just about anybody needs in terms of hourly demand except for perhaps a warehouse, but that is not the point of the GARN. The GARN can run at maximum efficiency, which is maximum output, for it's entire burn, regardless of demand. Excess heat is stored in the water, and drawn off during and after the burn as needed.

Andrew - the only downside to excess storage is standby loss. The GARN, as any other storage tank, needs to be well insulated to reduce standby losses to a minumum. This is not difficult, but should be considered in your analysis and comparison of systems.

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I have a similar sized property, my current peak is over 400,000k. I was not thinking of 8 Garns.

With this heat load I would be looking at something a lot less extreme.

However, each to their own.

I hesitated to wade in too early here as there are strong sentiments toward the Garn. I would like to avoid a flame war if possible. A carbon steel Garn should have about a 25 year life & this is long for a gasser. A stainless WG should last about 3 times this. No, I do not have test results. Look at other applications of stainless over carbon. At the end of the Garns life you will need to replace it. What is a 2034 Garn going to cost, $30,000? $40,000? If you are 70 years old this all a moot point. A Garn is a great boiler, it seems to be trouble free. A stainless WG can burn wood with 40 percent moisture. I looked at a stainless WG where the owner was burning well seasoned wood(1 maybe 2 days). Yes the efficiency is lousy. This is better than turning on your oil burner because you ran out of dry wood though. How many times have you read on Hearth where someone has run out of dry wood? With a stainless WG you can burn cheap wet wood if you need to without damaging the boiler. Garn people etc, don't tell me you can't because I've seen it done. A stainless WG with or without storage is in my humble non expert opinion, the last boiler you will probably ever need to buy. Randy

I have only seen one garn, a 1500, installed about 6 months ago and they burned unseasoned wood as they had not stocked up in anticipation. Pine, Aspen.

The only negative comment about the Garn was that they had to feed it 2 or 3 times a day......

I have looked at the Woodgun, my comparison would be between the 500,000? model and the Garn 3200 or 2x 2000. Probably the cost comparison is similar, the Boiler is a relatively small percentage of the total instal costs. Current plan is one 2000 and space for another. Hoping I will not need it. Just something that comes to mind, somebody said the 3200 was better for solar add on?

I have never heard of a Garn failing, I have no reason to believe a SS WG would.

Singed - no flame wars here. Just sharing of opinions and experiences. What damage do you think would happen if you burned unseasoned wood in a GARN? I have burned wet wood without issue. Buring green wood in the GARN is the same as the WG or any other gasser - less efficient, resulting in more fuel usage, like Durango pointed out. The GARN uses sched 40 boiler piping for the flue/HX, which is pretty durable. With the high rate of airflow - you do not get excessive (any) deposit buildup on the tubes, at least in my experience. You just waste energy boiling off the water in the green wood instead of putting it into storage or the house.

Andrew - the relatively small efficiency difference between the GARN and the WG would be moot when you add storage to the WG. Since it is not integral, you will need another HX to transfer the heat to the storage water, and that step results in a loss in efficiency. If you put the GARN in your basement, the standby losses from the storage will also go into your home. Can you fit the GARN in your proposed basement design?

My wood gun is awesome. simply put. My first season was last year. Minimal maintenance, once a week ash removal from the tubes and cyclone collector. Burned some less than ideal wood, and it ate it up with no issues. The Wood gun was the only choice for me as it was the only system that was built for steam production. I have a one pipe system that after the install made no noise whatsoever. The previous utica oil steamer clanged and banged, hissed and pissed. Of course i did radically change the near boiler piping so it would be quiet. In 2007 I burned 1700 gallons of oil. This past winter was 28 face cord. Now that may seem like a lot but remember this is a steam system with no storage 1860's two story farmhouse with a supercold long winter. Hope this helps... probably not. Also all i did was feed it wood and clean the ashes, no other maintenance. 280 degree stack temps by the way. Please use all stainless flue for any gassifier.. One time install lifetime use.

Dry steam said:

My wood gun is awesome. simply put. My first season was last year. Minimal maintenance, once a week ash removal from the tubes and cyclone collector. Burned some less than ideal wood, and it ate it up with no issues. The Wood gun was the only choice for me as it was the only system that was built for steam production. I have a one pipe system that after the install made no noise whatsoever. The previous utica oil steamer clanged and banged, hissed and pissed. Of course i did radically change the near boiler piping so it would be quiet. In 2007 I burned 1700 gallons of oil. This past winter was 28 face cord. Now that may seem like a lot but remember this is a steam system with no storage 1860's two story farmhouse with a supercold long winter. Hope this helps... probably not. Also all i did was feed it wood and clean the ashes, no other maintenance. 280 degree stack temps by the way. Please use all stainless flue for any gassifier.. One time install lifetime use.

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I have contacted WG. Just wondering what you heat loss, how you sized your Boiler?

Dry steam said:

My wood gun is awesome. simply put. My first season was last year. Minimal maintenance, once a week ash removal from the tubes and cyclone collector. Burned some less than ideal wood, and it ate it up with no issues. The Wood gun was the only choice for me as it was the only system that was built for steam production. I have a one pipe system that after the install made no noise whatsoever. The previous utica oil steamer clanged and banged, hissed and pissed. Of course i did radically change the near boiler piping so it would be quiet. In 2007 I burned 1700 gallons of oil. This past winter was 28 face cord. Now that may seem like a lot but remember this is a steam system with no storage 1860's two story farmhouse with a supercold long winter. Hope this helps... probably not. Also all i did was feed it wood and clean the ashes, no other maintenance. 280 degree stack temps by the way. Please use all stainless flue for any gassifier.. One time install lifetime use.

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Dry steam, I do like the wg. Better than alot of other boilers but, there is always a but with me I'm very picky. The combustion chamber brick is unique and from other wgs that I talked those pieces you probably will be replacing them a few times in the life of the boiler.

A garn has standard 1.25 firebrick that can be purchased at any farm store and you yourself can make the secondary refractory, nothing special there. I have even seen a garn operate without the secondary refractoy MOF, I think it still is!

And of all the garns that I've seen, I have not seen one with stress cracks in it. When you start to size down boilers there becomes alot of angles, alot of "tightness", ( square doors, 3 sided corners, etc.). Garns are rounded on the critical surfaces which allow for equal expansion

Garns are not perfect, but in my opinion they are by far the best and simplest design out there.

Hi Jim K; Would you describe the construction of your Garn boiler in detail. I have never seen one & I don't believe the website gives sectional views. I've read this is a simple well engineered boiler & I'm assuming Mr Garn doesn't want this copied. The Garn is obviously one of the best boilers made, judging by satisfied owners. I wonder what the life of this unit really is. I had heard 25 years, this could be incorrect with a well run one. That huge water jacket over the fire is simply, a huge advantage. Randy

Singed Eyebrows said:

Hi Jim K; Would you describe the construction of your Garn boiler in detail. I have never seen one & I don't believe the website gives sectional views. I've read this is a simple well engineered boiler & I'm assuming Mr Garn doesn't want this copied. The Garn is obviously one of the best boilers made, judging by satisfied owners. I wonder what the life of this unit really is. I had heard 25 years, this could be incorrect with a well run one. That huge water jacket over the fire is simply, a huge advantage. Randy

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Randy, I don't have actual garn bp's but here are my pics of my home built garn style

https://www.hearth.com/econtent/index.php/forums/viewthread/11262/

You can get a idea of how they work from these

Hi Garnification; That is an impressive boiler. Is all the tubing that is pictured submersed in water? There is the top row of tubes, I believe the schedule 80 & a large tube underneath this. Do the flue gasses go though the large tube & into a back chamber & then out through the top bundle? Thanks for the pics, they show what a great boiler this is, Randy

Singed Eyebrows said:

Hi Jim K; Would you describe the construction of your Garn boiler in detail. I have never seen one & I don't believe the website gives sectional views. I've read this is a simple well engineered boiler & I'm assuming Mr Garn doesn't want this copied. The Garn is obviously one of the best boilers made, judging by satisfied owners. I wonder what the life of this unit really is. I had heard 25 years, this could be incorrect with a well run one. That huge water jacket over the fire is simply, a huge advantage. Randy

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Singed - this is the only cut-away diagram I know of. The fire box, secondary reaction chamber, and all 50
+ feet of flue/heat exchanger are submerged in the storage water. The draft induction fan pulls air through the rear air intake, and into the fire box via two "nozzles" or ports. The entire firebox and flue is under negative pressure except for the last 11 feet of flue. The fan is large, driven by a 3/4 hp Dayton Jet pump motor. The fan and the door are the only two moving parts in the whole system.

As Garnification pointed out, the fire brick lining the lower third of the primary fire box is off the shelf stuff. I did not know you could make the SRC lining though! Replacement of the SRC lining is something that is not likely to be necessary for many years, unless you are careless in loading and damage it.

There are lots more posts on the GARN here. It is NOT the best solution for everyone, but if you have the room to set one up, you will have a very efficient and easy to use alternative heating unit.

Hi Jim K; Thanks. What a neat boiler, great picture. I am surprised at the amout of heat exchange area. It appears this changes from negative to positive pressure at H & I is the bundle of tubing. Now I know why this has such a following, Randy

I am curious as to the cost of electricity per month running a Garn ? Thanks .

Singed Eyebrows said:

Hi Jim K; Thanks. What a neat boiler, great picture. I am surprised at the amout of heat exchange area. It appears this changes from negative to positive pressure at H & I is the bundle of tubing. Now I know why this has such a following, Randy

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Yes - the pressure change is at "H". But there is no bundle of tubing at "I" like in Garnifications design. It is a straight run of pipe out to the rear wall of the GARN. By the time the flue gases get to the outlet, temps are down in the 250-300 degree range, down from 2400+ in the SRC ("F" in the diagram). You are correct that there is a lot of HX surface area.

Gagz said:

I am curious as to the cost of electricity per month running a Garn ? Thanks .

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I don't think the GARN fan pulls a constant 11 Amps, but assuming it does you can calculate the cost as follows.

It will depend on how often you run the unit. In the coldest parts of the winter I burn twice a day for 2-3 hours. Watts = Volts x Amps. So if you ran it on average once a day for 3 hours, you would use about 4 Kwh/day. If you pay 12 cents/KWH (change this to whatever you are paying), you would spend about $15/month in electricity. Of course that is just the operation of the GARN. Your circulation pumps and zone valves will add a little bit to that, regardless of which heat generating system you use.