Do all indoor gasifiers have a small firebox?

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bpirger

Minister of Fire
May 23, 2010
632
Ithaca NY Area
In my search for a gasifier, I'm starting to get a little scared of the nearly $20K for a Garn with the garn barn and all the associated trimmings.

It seems like an indoor gasser with storage might be a bit cheaper, albeit placed outside in an insulated shed.

Question though becomes are there any indoor gasifiers with a firebox at least 24" long? I can't imagine cutting all my wood to 18" or even being relligious about 20". My wood stove now takes 24" and often pieces are diagnonal....

I had ruled out the outdoor Econoburn becuase of the limited 22" firebox. I don't need 36"....but 30" would be ideal....but 18-22" just seems to be "wrong" for my mindset with an outdoor setup.

Am I missing something indoors?

Thanks to all!


One last bonus question: If one no longer burns oil, how long does fuel oil stay good for sitting around for backup?? Is that a legitimate concern?
 
I can answer my own question...no, they don't! I see the EKO60 and BioMass take bigger wood. Becoming more attractive indeed! I need to put all the numbers together and compare to the garn.

Storage pricing has to consume another evening of reading...this stuff is to damned addicting. It's 3:30 AM, I started at 9!

So is BioMass a copy of the EKO line then? They look similar, and have the same importer I believe, same controller, and even a similar user's manual. Are they both Polish in origin? Maybe just like US companies, the partners split up....

Thanks again to all.
 
bpirger said:
In my search for a gasifier, I'm starting to get a little scared of the nearly $20K for a Garn with the garn barn and all the associated trimmings.

It seems like an indoor gasser with storage might be a bit cheaper, albeit placed outside in an insulated shed.

Question though becomes are there any indoor gasifiers with a firebox at least 24" long? I can't imagine cutting all my wood to 18" or even being relligious about 20". My wood stove now takes 24" and often pieces are diagnonal....

I had ruled out the outdoor Econoburn becuase of the limited 22" firebox. I don't need 36"....but 30" would be ideal....but 18-22" just seems to be "wrong" for my mindset with an outdoor setup.

Am I missing something indoors?

Thanks to all!


One last bonus question: If one no longer burns oil, how long does fuel oil stay good for sitting around for backup?? Is that a legitimate concern?
Click to expand...
Yes The eko60 and 80 take longer wood. I bought the 80 partly because of that as I wanted to cut my small dia wood longer (30in).
That said I still cut my wood in the 18 to 20in range as it tends to dry better than much longer. The larger the firebox and more water in the boiler the harder it is to get up to GOOD gasification from a COLD start. My sons eko60 is easier to get gasifing than my 80 at a COLD start. During the winter it's not a problem but now when I run it only every 7 to 10 days for DHW it takes a while to get it going.
IMHO a 22in box would not deter me from buying but a 18in would as you really should have a inch or to space on the ends for air movement so an 18 in would mean that MOST of the wood would have to be 16in or under.
As far as having a large volume firebox, that can be conterproductive if you don't do a complete burn and idle as then you are running like the OWB's and having an incomplete burn. Also I have found that with my 80 that because of the large volume it pulls alot of heat just getting the large volume of wood up to temp so that it gasifies good. But I have 2000gals of storage so I do complete burns so the large volume is an advantage for me.
If you are going to use storage I would recomend sizing the boiler a size larger than your heat calc call for but if no storage I would size it for only the size you need. Bigger isn't always better in this case. If you are going to have alot of storage then larger is better as you don't have to refuel it as often getting the storage up to temp.
It depends on alot of factors and every case is different as to how much you are doing the work yourself, DIY materials, avilabity of storage tanks and types, and other things but every thing being equal then I would consider the garn. I do think the garn is probably the eaisiest gasifier to run and maintain, It's big, balky, and takes a special place but it is Easy to load and start, has it's own storage, and has a proven long term record. It also has horizonal flue cert. and in some places that can be a plus.
leaddog
 
bpirger said:
I can answer my own question...no, they don't! I see the EKO60 and BioMass take bigger wood. Becoming more attractive indeed! I need to put all the numbers together and compare to the garn.

Storage pricing has to consume another evening of reading...this stuff is to damned addicting. It's 3:30 AM, I started at 9!

So is BioMass a copy of the EKO line then? They look similar, and have the same importer I believe, same controller, and even a similar user's manual. Are they both Polish in origin? Maybe just like US companies, the partners split up....

Thanks again to all.
Click to expand...

I think the BioMass design is based on the EKO.

With gasifiers, getting the longest possible wood into the firebox is not necessarily the way to go - search for threads on 'bridging'. You'll also be burning a lot less wood, so the extra effort of cutting wood into shorter pieces may be less than you think. Gasifiers also need wood to be dry, and shorter pieces dry more quickly.
 
i went with the eko 60 and home made storage for the same reason, to save 10K on the price of a garn. I got installed and running for about 11K and I've been pretty happy with the results. The 60 box is big enough for longer logs I use about 24-28 " logs in it.

The Garn is a beautiful unit and more efficient than my setup but I think I have captured about 85% of the Idea with an EKO 60 a flat plate HX and a 1500 gal insulated Cinder block square water tank.

I just don't think you can beat the Idea of having your combustion INSIDE the water tank and a very long set of HX tubes to get the heat into the water as Garn does. But I could not justify the added money. I would say add pressurized storage and eliminate the HX altogether would be the most I would do and the efficiencies would be very close for less money.

The EKO 60 is a big beast and works best with a refill, takes an hour or to to get running and then pushes out the BTU's. Good to pair it with big storage and let it heat the water.

My take at this point is:

Good - Gasser + open DIY storage = Low dollars and high efficiency DIY Tank cost me 500$
Better - Gasser + Closed storage = Medium dollars and Higher efficiency - 3 500 gal propane tanks add to the cost , less one HX
Best - Garn =Very High dollars and Very high efficiency
 
I would not grossly oversize a boiler, relative to the design load, just to get a larger firebox. In addition to the issues mentioned you have more heatloss from a larger boiler and more expense in piping, flue, etc. Cold in-efficient burns contribute more harmful emissions also.

hr
 
In downdraft gasifiers, burn time is diametrically opposed to efficiency when operating without storage. This has to do with the ratio of heat produced by the low temperature and innefficient combustion of the upper chamber compared to the heat produced by the efficient combustion of the secondary burn. In short, the larger the firebox (and thus fuel load in the upper chamber), the greater portion of your heat load that will be satisified by the inneficient combustion therein... causing more idling, increased emissions, reduced efficiency, and perhaps a serious creosote problem.

I recommend sizing the boiler to keep the burn times at 8 hours or below to maintain a decent balance between efficiency and burn time when burning without storage. You can also limit the load in an oversized boiler to reduce burn times and increase efficiency. Without storage, it's best ot keep the smallest, but hottest fire possible.

I wish more people could experience running these boilers with thermal storage.... those with second thoughts about the cost and "hassle" of installing it would likely change their minds.

cheers
 
I ask about the firebox size only becuase of the length of log it can take....only because when cutting I'd hate to be locked into everything 20" or less. My woodstove takes 24" I believe (Lopi Liberty) and every now and then I'm too long and have to throw it outside for another cut. I agree....fast and hot is the way to go. I also agree storage is the answer.

Can you actually achieve an 8 hour burn in a gasser into storage? I'd think it would be much shorter than 8 hours.

I'm focusing now on storage. I'd love the Garn, but I don't like the price tag. BUT, it seems an indoor gasser (like an EKO 60 or BioMass 60) with storage would be great....but it seems to get 1000 gallons of pressurized storage would put me close to the garn 1500 price tag. If I'm within a couple of thousand, I'd just buy the Garn. About $7000 for the boiler, $5K for 1000 gallons of pressurized storage (those red 490 gallon tanks from New Horizon anyways), and you are at 12000. $2000 more for the Garn 1500....with an additional 500 gallons of storage!

So, my quest is now for less expensive storage....is it out there? Pressurized seems to be the way to go. Searching for a propane tank and having the mods made is an option...though I'd have to pay for the welding etc. so not sure what that would end up being. I see the refurb tanks that are stacked (is that the Ahoa people...or similar). Need to get some pricing info.

Non pressurized storage can be cheaper....but with all the radiant I have, it sure seems that the extra 30 degrees or so I'd get in the storage would be really nice.....

Love this site!
 
I don't know if it makes any difference, but radiant heat is an advantage if you're using non-pressurized storage. The problem with non-pressurized storage is that there's a heat exchanger between storage and the rest of your system. That results in an unavoidable temperature difference between the storage temp and the temp of the water going to your zones.

With baseboard, that temperature difference is a problem almost all the time, because baseboards are designed to operate with 180 degree water. Non-pressurized storage at 180 will give you water to the zones at a lower temp, decreasing the output of your baseboards. At some point, the water temp to the zones is too low to provide enough heat output. This can happen at storage temps of 160 or even higher depending on how much baseboard capacity there is and how cold it is outside.

With radiant, you'll get usable heat out of storage for much longer.
 
Thanks nofossil. But with pressurized storage, I can get considerably higher temps, so longer storage times....right? So with baseboard, unpressurized storage only will provide 170-140 or so....maybe 180-140. But for radiant, I'm good from 170-120 easily, maybe even lower (though DHW will get tough below 130 I'd thnk). Whereas with pressurized, I baseboard can get 190-140 and radiant 190-120.... So pressurized storage provides an extra 20*1000*8=160000 BTUs to radiant....but doubles the cost or so (with 1000 gallons of storage). Sound about right?
 
I have $765.00 in two 500 gal. propane tanks and a homemade expansion tank and that includes new primer, paint, and trailer rental to haul them but no plumbing. So no storage dosn't have to double the price of
your system.
 
bpirger said:
Thanks nofossil. But with pressurized storage, I can get considerably higher temps, so longer storage times....right? So with baseboard, unpressurized storage only will provide 170-140 or so....maybe 180-140. But for radiant, I'm good from 170-120 easily, maybe even lower (though DHW will get tough below 130 I'd thnk). Whereas with pressurized, I baseboard can get 190-140 and radiant 190-120.... So pressurized storage provides an extra 20*1000*8=160000 BTUs to radiant....but doubles the cost or so (with 1000 gallons of storage). Sound about right?
Click to expand...

usefulness of dhw from storage depends on what type of heat exchange you are using and how hot you like the water to be in your dhw tank, and whether or not you zone the dhw, or just use a pre-heat piping plan. Just remember the bigger the heat exchanger, the less differential there will be between your storage tanks and your dhw tank. A large brazed plate and pressurized storage (properly piped) will produce a differential of only a few degrees... this makes it possible to use relatively low storage temps to make dhw as well as keep your tanks from mixing by reducing the circulation time required to recharge the dhw. IF you are ok with letting your dhw drop to 110 near the end of the storage cycle, (which is a very usable temperature) you can use storage temps well below 130.

you will want to make sure that you allow your dhw tank to reach 140 on a regular basis to keep bacteria from growing inside.

cheers
 
All of these things get more complicated as you start going into the details.....

The heat exchanger (and additional circulator, depending on design) required for non-pressurized storage can easily result in non-pressurized storage costing more.

There are two common flavors of heat exchanger: Immersed coil and external flat plate. Non-pressurized storage requires one or the other. Immersed coils are wicked expensive, depending on the current cost of copper, but don't require a second circulator that you need with a flat plate. Actually, flat plate exchangers really need two additional circulators if you're going to charge and discharge properly: Charge storage with top-to-bottom flow, and discharge with bottom-to-top flow. Told you that this gets complicated. Some of these issues led me to create the 'simplest pressurized storage' sticky.

In my mind, there are two main advantages of non-pressurized storage:

1) Some designs are easy to get into places where a pressurized tank would never fit.

2) You can have multiple immersed-coil heat exchangers. I have three: one for storage-to-heating (boiler and zones), one for DHW preheat, and one to allow heating storage with my solar panels. That's a lot more difficult to do with pressurized storage.

Advantages of pressurized:

- Higher performance due to no intervening HX.
- Easier to insulate
- No evaporative loss
- Simpler plumbing (compared to non-pressurized with external flat plate)

For any given size of storage, pressurized gives you a higher effective heat storage capacity. Same with radiant heat.

I 'supercharge' my DHW when the boiler is running, and preheat the makeup water from storage. That gives me three days of usable DHW from a 40 gallon tank.
 
I have $765.00 in two 500 gal. propane tanks and a homemade expansion tank and that includes new primer, paint, and trailer rental to haul them but no plumbing. So no storage dosn’t have to double the price of
your system.
Click to expand...

765 for 1000 gal seems like a no-brainer. My HX was about 500. the Tank matierial another 500 so that is pressurized storage at the cost of un-pressurised. Nice!

Is this a Great deal or can tanks be regularly had in the 400 each range ?
 
My unpressurized storage system is 346 gallons (my heat load is quite small).
Last winter, I ran it up to 170-180 but usually stopped at about 160F since that would carry us one to two days in winter.
I could run the system down to 109 and still get decent DHW, but it was not scalding.

There is only one hx (the DHW one) in the tank. Although we manufacture smooth copper coil hx's I still have to buy them and I am probably as cheap as anyone, so
we ran the boiler unpressurized and also the radiant heat loads unpressurized.

Our hx are simpler than others since they are made to hang on the side of our tanks, so there is no plumbing in the tank.
They are not inexpensive, but the system is quite adaptable. I cannot fathom messing with getting a big heavy tank into a basement, much less stacking them and insulating.
But that is why we make our tanks.

We can actually make space heat exchangers even less expensive, but the limiting factor is not heat exchanger thermal performance, but rather
pressure drop.
 
atmospheric storage also lends itself to easy integration of thermal solar.

cheers
 
[quote author="Piker" date="1276894995"]atmospheric storage also lends itself to easy integration of thermal solar.

That is right.
We got started making solar drainback tanks, wood boilers came later.

Once an unpressurized thermal storage system is in place, you own one half of a solar heating system with all the interfaces already installed!
 
mwk1000 said:
I have $765.00 in two 500 gal. propane tanks and a homemade expansion tank and that includes new primer, paint, and trailer rental to haul them but no plumbing. So no storage dosn’t have to double the price of
your system.
Click to expand...

765 for 1000 gal seems like a no-brainer. My HX was about 500. the Tank matierial another 500 so that is pressurized storage at the cost of un-pressurised. Nice!

Is this a Great deal or can tanks be regularly had in the 400 each range ?[/quote

When I was shoping around I found a lot of 500 gal tanks in the $350.00 range. The ones I got were $250.00 each but I have to take the rust and loose paint off and prime and paint. Then for an expanson tank I found what I think was a steam boiler condinsing tank on craigs list for $125.00 that also needed the finish re-done. Some people use 100 gal propane tanks for expanshion. got the exp. tank painted and 1 propane tank primed. It would easily be worth an extra $75.00 each to not have to strip and paint the big tanks. My expanshion tank is 80 gal and I'm not sure thats big enough so I may have to add a small tank to it.
Click to expand...
 

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Great questions and concerns by the way... Almost 60% of our 1000 customer sites are indoor units in an outdoor facility (wood shed, GARN barn etc). We have GARN WHS customers in our market area from Greenville SC to Cincinnati OH to Lake Plaid - even East to VA Beach VA. All of them are happy with the slight increase in payback time compared to the multiple decades of serviceability. So you are good to consider the GARN® Brand. I finally have plans to implement my own in Jan 2011. Another option is a US made modular storage tank in two proposed sizes - 1200 gal and 1500 gal - both cubical (which is most space efficient), approx 6' x 6' x 6'. Expect the same serviceability as the GARN. We expect to provide these to our customers by the coming heating season. They are very affordable are are a great companion to our indoor downdraft gasifiers like the Empyre Elite (UL/EPA/CSA/fossil backup) (And uses 24in cord wood or our 7lb bricks) and the ATMOS available from 68kbtu to 205kbtu. Basically the heart of any system must be Hydronic Thermal Storage and and a bow to Martin Lunde (yes "cult like") for doing it RIGHT since the "first" energy crisis of the '70's. Many GARN's out there are over 33 years old. Oh yes - and sorry I keep jumping around - the "indoor gasifier outdoors" will be subject to the expense of vertical venting for most/all brands because of UL or local and state legal requirements. Here the GARN WHS has an edge with the horizontal (or vertical) offering. Where are you in Ithaca - I live about an hour away (near Corning). -mark 607-731-4227 mobile.
 
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