Big Boy Decision Time

[jebatty]

An environmental educ institution a couple of miles from me will be inking the deal on 1-2 big boys, either Garn or Woodgun, each in the 1/2 million to 1 million btu output range. I've followed most posts on these, as they have come up, but have not seen much on the big ones. The Garn storage is a plus but not a deal maker alone.

Greatly would appreciate some final input to relay to the director indicating your most incisive observations about each to help in the final decision:

1) ease of loading and daily operation
2) routine cleaning/maintenance
3) major cleaning/maintenance
4) service life expectancy
5) realistic average output vs rated output
6) issues to think about
7) surprises ?
8) what else ?

The director is well aware of the need for dry wood (25-30% MC), the institution has available an ample wood supply. The boilers will be used as a teaching tool as well as replacing and supplementing existing LP boilers.

Thanks for your incisive comments.

 

[TCaldwell]

Jim,have these people visited or inspected in operation either of their current choices. By this forum the garn is a known entity, probably not for everyone but well proven, what do we know about the wood gun other than it has a few high output models. I would think somebody has some flue gas analyser results,one parameter for direct comparison.

 

[pybyr]

An environmental educ institution a couple of miles from me will be inking the deal on 1-2 big boys, either Garn or Woodgun,
Thanks for your incisive comments.

FWIW, Econoburn also makes some Uber-sized units in the Mega-BTU range, and if they are anything like my Econoburn 150, they'll work well and are built like the proverbial tank.

 

[Como]

2x Garn WS 2000

Unless you wanted to go high tec.

Or you could have one of each?

 

[Gooserider]

I will say I was impressed by the Garn that I saw up in Bangor at the boiler show... The guy was showing photos of what he said was their biggest known install, a multi-unit cooperative apartment complex, I forget just what the unit count and square footage was, but it was very substantial... Supposedly the original plans called for two Garns in parallel, but aparently they ran out of money and ended up only getting one, which was still able to handle it, although it had to be fed every 4-6 hours in the coldest weather. That it could deal with the load was impressive in itself, but the other thing that was noteworthy is that the unit did so with minimal care and maintainance... They had to periodically replace the fire bricks, and stuff like door gaskets but that was about it.

Seems to me like the Garn has a big advantage in being a "stone axe" simple design - not many moving parts, and those being pretty much off the shelf type items. This would seem to me like a big advantage for an installation where you are likely to have a lot of operators that might or might not know what they are doing, or care about the equipment like it was their own...

Gooserider

 

[Singed Eyebrows]

That's a tough choice. The Wood Gun doesn't require a chimney as I was told, it doesn't require storage. When the intake flap closes "all" air is cut off to the unit & heat production drops fast. You would want the stainless WG as any intake leaks in the carbon steel one will rot it out(you would get a low grade smoldering fire). I don't know anything about the Garn except its great rep on here. A friend of mine just bought a stainless WG & was very impressed with the weld quality & fit & finish, & he is picky. The WG will take 40 percent moisture wood(you will lose efficiancy). You will not damage the boiler though. Pretty hard to damage 304 SS. I got to see a WG(stainless) in operation & the owner was very happy with it. As good as the WG is & I wish I could have afforded one, I think the Garn holds an advantage though in this case. Randy

 

[muncybob]

That's a tough choice. The Wood Gun doesn't require a chimney as I was told, it doesn't require storage. When the intake flap closes "all" air is cut off to the unit & heat production drops fast. You would want the stainless WG as any intake leaks in the carbon steel one will rot it out(you would get a low grade smoldering fire). I don't know anything about the Garn except its great rep on here. A friend of mine just bought a stainless WG & was very impressed with the weld quality & fit & finish, & he is picky. The WG will take 40 percent moisture wood(you will lose efficiancy). You will not damage the boiler though. Pretty hard to damage 304 SS. I got to see a WG(stainless) in operation & the owner was very happy with it. As good as the WG is & I wish I could have afforded one, I think the Garn holds an advantage though in this case. Randy

The Wood Gun doesn't require a chimney????

 

[Gooserider]

Far as I know, the Wood Gun DOES require a chimney... At least none of their literature says, or implies that it doesn't. Since it would be a "differentiator" and a nice advantage, I'd expect it to be mentioned if they didn't.

In addition, they give a spec for flue diameter, which implies a flue to me... Lastly, the demo unit I saw up at the Bangor Boiler (and other woodsy stuff) Show was using a chimney.

The WG is different in that it exhausts out the side of the unit, instead of the rear like everyone else, and then runs the ash through that cyclonic separator, but far as I know, from there it expects to go into the same sort of chimney as anyone else...

The only cordwood burner I know of that can be side vented is the Garn.

Gooserider

 

[Gooserider]

Far as I know, both the Garn and the Wood Gun can take a power failure without much of a problem - Power goes out, the blowers stop, which cuts the draft to the point where the fire goes out or dies down to a non-problem level... More of a concern IMHO is that when the power goes out, so does the heat circulation to whatever you are burning the boiler to keep warm.... Some of the boilers do require an "emergency dump zone" that can be convection driven - what I've heard mentioned as a common solution is to fasten a few feet of scrap baseboard to the ceiling of the boiler room, with an automatic valve that only opens when the power goes out... (I would probably try to run everything through a UPS to keep at least the circs going as long as possible.

Gooserider

 

[Singed Eyebrows]

As told to me by the factory, the WG does not require a chinmey. This is not your typical gasifier. The WG is induced draft all the way through the center heat exchanger tube. The flue gas is then spun by the fan as GR mentions & cleans the other section. After the flue gas hits the fan the WG is forced draft. At no time in this process does the WG need a chimney. When the WG shuts down a motorized flap closes & the boiler should be airtite. A chimney is not required here either as the flue gasses are expected to condense on the sides of the boiler & burn off again when started up. A good chimney draft will actually hurt the carbon steel WG as it will try to pull air through gaskets. All these problems are a moot point will the stainless WG. I was going to buy one of these & did a bunch of research. I gave the nod to the Garn for ease of use & the large water jacket. If it was based on how long it will last I think a stainless WG will be around a lot longer than a Garn, Randy

 

[Gooserider]

Well, I just checked the WG website again... I did find the following on this Knowledge Base page (bold added)

The Wood Gun™ versus Competitors

Unlike our competitors, the Wood Gun™ is available in both carbon steel and stainless steel models. Carbon steel models, the standard across the industry, are less expensive than stainless models but more vulnerable to corrosion and durability issues. The expected lifespan of carbon steel boilers is only 10-20 years. The lifespan of stainless steel units, on the other hand, is yet to be determined. There are currently stainless steel Wood Guns that have been in operation for 21 years and counting with no sign of deterioration. Stainless steel models can burn a wider variety of wood, both in moisture content and species, without fear of corrosion than carbon steel models. Both models of Wood Gun™ have much longer burn cycles and operate at lower exhaust temperatures (an indicator of total efficiency) than our competitors' units. Also, all Wood Gun™ boilers may be installed in an outbuilding without a traditional chimney because they create their own draft. In general, we believe that our wood gasification boiler design is superior to our competitors' in both quality and durability. Most of our competitors in the wood gasification market only focus on the residential segment. We offer an expansive product line that includes larger boilers aimed at the mid-level commercial as well as the residential market. In comparison to similar offerings by our competitors, our carbon steel Wood Guns are competitively priced across the board. The stainless models are from $1,500-$2,500 more expensive to cover the higher cost of stainless steel. This is offset, however, by the fact that the stainless steel Wood Gun™ does not require the heat storage system that is highly recommended for carbon steel machines (see Why is Heat Storage Not Required with the Wood Gun?). A heat storage system typically costs between $5,000 and $7,000 and requires a great deal of physical space for installation. The bottom line is that the Wood Gun is less expensive and more durable than our competitors' products.

I'm not at all sure I buy the shutdown claim as to not needing storage, and some of the other statements, but that is not on topic for this thread...

Even the statement above is not real clear, as they don't say what IS required for venting - one could argue that a standard OWB doesn't have a "conventional chimney" either, so a lot more definition is needed... However the only photo of an install showing a house (the one where they show the steam condensing) is showing a standard chimney...

OTOH, a pellet stove is clearly designed to be vented through the wall. Similarly Garn has made it quite clear that one of their reccomended venting options is through the wall, sort of like a pellet vent but a LOT bigger (and with specific requirements for pipe design, clearances, and so forth...)

I have sent the Wood Gun folks a ding on their contact form asking what their specific venting requirements are in an effort to clarify the answer... I am curious, because if I could go through the basement wall the same way our mod-con gas furnace does, that would save a certain amount of headaches....

Gooserider

 

[Singed Eyebrows]

Hi Gooserider; I talked to Patrick personally & he was the one that informed me that the WG doesn't need the chimney & at the time this just wasn't of much interest. As I thought about it later I could see that if the boiler closed down airtite as it should all a chimney draft would do is pull a vacuum on the boiler, no real benefit to that. As to why this great feature is not in their literature as you mentioned is anybodies good guess. Hopefully somebody at WG can clear this up for everyone & hopefully I didn't stear the original thread poster or anybody wrong, Randy

 

[Gooserider]

Hi Gooserider; I talked to Patrick personally & he was the one that informed me that the WG doesn't need the chimney & at the time this just wasn't of much interest. As I thought about it later I could see that if the boiler closed down airtite as it should all a chimney draft would do is pull a vacuum on the boiler, no real benefit to that. As to why this great feature is not in their literature as you mentioned is anybodies good guess. Hopefully somebody at WG can clear this up for everyone & hopefully I didn't stear the original thread poster or anybody wrong, Randy

No problem - it just seems like something that needs to be cleared up... I do wish that Wood Gun would make their install manuals available online - I can't find them on the site, I just looked...

Gooserider