Gasification quandry

[rvtgr8]

My wife and I have built two homes on our sixty acre ranch near Elbert, Colorado on the Palmer Divide. We built in a wooded area and so we have unlimited supplies of downed timber for firewood. Our first home (now our guest quarters) was a hybrid straw bale design. It is small and takes almost nothing to heat it. Our small Lopi wood stove could run you out on the coldest of days. We built our second home completely of surplus materials. It is well insulated (8" cellulose filled walls with two layers of 5/8" osb sheathing, red cedar siding and a wainscot of natural stone. It has a concrete tile roof. It is framed in steel. We put radiant heat in the floor. We have a propane Burnham boiler with a side arm that heats our hot water. We want to add a gasification boiler in the garage. Being on a fixed income, skyrocketing propane costs are taking a bite out of the budget. Gasification seems a logical choice for us. With that introduction in mind, I have several rather complex questions:

1. I am currently heating 2,500 s.f. and I would like to eventually consider adding an arm to our 1,000 s.f. green house. We average $100 per month on propane now with the 136,000 btu Burnham. Should I go for a larger gasification boiler in terms of btu's?
2. I am down to either an EKO or Biomax out of W.V. and I have had some interest in a Greenwood. I was a bit discouraged about troubles expressed in this forum over the cracking in the masonry lining of the Greenwood. Is one of these units substantively better than the other? Since I will be doing most of the plumbing myself, is one of these brands more complicated (in terms of installation) than the others?
3. I am going to frame in a boiler room in my attached garage. Can clearance distances be safely reduced by lining the boiler room with cinder block? Also, fresh air is an obvious consideration in a boiler room. Is it feasible to force air into the BR based on the burn requirements? This question will obviously prove that while I will try to build anything under the sun, actually knowing what I am doing does not get in my way;-) .
4. Should wood storage be outside of the BR?

I am including a picture of our home. My wife and I did all of the work ourselves and it is something of which we are very proud. Now if we can just heat it with a gasification boiler, we might finally be able to get on with retirement dreams.

Robert

 

[Eric Johnson]

Welcome to the Boiler Room, Robert. Nice looking place you've got there. Sounds like you're the kind of guy who will appreciate a gasifier.

I have the EKO 60, which I got from Cozy Heat (upper banner), and it was not difficult to install. Like you, my lack of experience and knowledge doesn't stop me from forging ahead when I think I can do something. We also have a couple of BioMax owners here, and I guess you're familiar with the Greenwood guys.

I have my boiler in a small cinderblock room in my barn. I also stack a winter's worth of wood around the boiler room, so everything is in one place, under one roof, and ready for just about anything. I don't have answers to all your questions, but the following two pics ought to help. I built the room for my previous boiler, which I pulled out to make room for the EKO. It's a tight squeeze, but everything fit, and it works like a charm. My combustion air comes in from the outside through a vent in the wall.

 

[jebatty]

You and your wife are to be commended on your ingenuity and creativity. My wife and I have heated our 50-yr old 1500 sq ft home in northern mn for 20 years with a free standing wood stove in a corner of our living area. Last Sept I self-installed a Tarm Solo Plus 40 (140,000 btu) gassification boiler in my wood-working shop, an old converted barn, 800 sq ft, 10 ft ceiling, and very poorly insulated. I am impressed with the Tarm and you also might want to look at the Tarm. Tarm makes both larger and smaller boilers.

"Should I go for a larger gasification boiler in terms of btu’s?" You should consider substantial water storage for the boiler to achieve long, efficient burn times, and so that the boiler does not need to fire/re-fire every time you have a need for heat. With water storage larger is almost always better than smaller. Others may have more info, but since I am thinking of moving from 800 to 1200 gallons for my shop, I would think you should consider at least this amount if not more. With storage, you might be able to actually reduce your boiler size from what would be required for a conventional boiler. For example, it takes about 10 hours of burn time to bring 800 gallons of water from 80F to 150F, and then I draw heat from the storage which lasts 1 - 3 days (boiler off) with outside temps ranging between 10-25 on the low side and 25-40 on the high side. Obviously we have much colder temps where I live, but these are not consistent for extended periods.

"Since I will be doing most of the plumbing myself, is one of these brands more complicated (in terms of installation) than the others?" I have no experience on this, since I only installed a Tarm, but I used as a guide the plumbing for a traditional LP boiler. Three key differences for me: 1) a boiler self-feed loop with a thermostatic mixing valve to better insure hot water always returning to the boiler. Wood gassification boilers operate much more efficiently if they are not fed with cold water on the return during operation. 2) using a plate heat exchanger plumbed into a short boiler loop to isolate the boiler from the heat side (also useful for DHW). This is not "needed," but I wanted to use antifreeze in the boiler and water for the heat loops. There are times when I may shut my boiler down for an extended time in the winter, and I wanted to take no chance of freeze-up. 3) boiler controls likely will differ, depending on make of boiler.

"I am going to frame in a boiler room in my attached garage. Can clearance distances be safely reduced by lining the boiler room with cinder block? Also, fresh air is an obvious consideration in a boiler room. Is it feasible to force air into the BR based on the burn requirements?" I think the answer to both is yes. Clearances for my boiler are the same as for a free-standing wood stove without heat shields, and actually side clearances could be reduced. 36" for the stack plus room for front loading are needed. I don't think my boiler draws anymore air than a wood stove, so air requirements are not huge, but fresh air is needed.

"Should wood storage be outside of the BR?" Lots of ways to go here. In general, I always burn 3rd year wood (dried two full seasons, burn following winter). I cut, stack and have well-ventilated, covered wood sheds for the wood. I burn almost only pine slab wood, and one wheelbarrow load covers 2-3 loadings of the stove. I prefer outside wood storage because of insects and pests, but a smaller quantity stored in the BR for convenience minimizes these problems.

Yours is the kind of house and living arrangement I would love to see sometime. Good luck.

 

[Nofossil]

I'll echo the previous post - good advice.

After a lot of head scratching, I went for the smallest boiler I could find - the EKO 25, which is rated for 80,000 BTU/hr. I'm heating a reasonably well insulated 3500 square foot house in Vermont as well as DHW and a hot tub. My peak space heating load is around 30,000 BTU/hr, so the boiler has more than enough capacity. I have 880 gallons of storage, and I can skip days if it's not too cold. Also, the house temp stays constant between fires. When I burn, I burn flat out for best efficiency.

I have a writeup on my system with diagrams and data on my site - link is in my signature below.

Good luck - I'm envious.

 

[rvtgr8]

Hey All,

Thanks for responding to me and giving me answers on my questions. This site is pretty remarkable. Not only are people knowledgeable about this heating technology, they are quick to share said information with the the the most novice among them.

I am now beginning to explore the concept of using hot water storage. The arguments for their use is somewhat compelling. The problem becomes space. I have been looking at the Garn, just because it combines both the boiler and water storage which I believe might make for a smaller overall footprint. Unfortunately, the Garn site was not helpful from a couple of angles. First, how much does one of these bad boys cost? Can't be cheap! Second, what are the standard sizes of this thing?

Robert

 

[Eric Johnson]

Garn is not known, at least not on this site, for prompt responses to sales inquiries. But the Garn is, by all accounts, an excellent choice in some circumstances.

There are a couple of things to bear in mind:

1.) The Garn is nonpressurized, so if you want to mate it to your existing hydronic system, you'll either have to convert your current setup to a nonpressurized state, or use a heat exchanger. I think the latter approach makes the most sense, but one of our members, Father John, said the factory strongly recommended the former. But it doesn't make sense to me.

2.) Most of us have learned the hard way that by the time you're done screwing around with storage and intank heat exchangers, you'll probably spend as much (or more than) the difference between the cost of the smallest Garn and a typical Euro-style gasifier, such as the EKO, Tarm or Econoburn with comparable storage. Not included in that calculation, however, is the cost of building or adapting enough space to house the Garn and associated insulation, etc.

3.) Even the smallest Garn is a lot bigger than most residential consumers would usually consider, on a btu/hour basis. But people like TCaldwell (another member) don't seem to have problems with that.

4.) Another one of our members, heaterman, is a Garn dealer, I believe. A friend of mine in Wisconsin Clyde Samsel at [email protected], is another. They might be able to answer specific questions, or give you the red-phone hotline connection to the Garn sales dept.

One nice thing about detatched hot water storage is that it can be located hundreds of feet away from the boiler itself, which can be a good thing. Of course, the flip side of that record is that you're going to have higher transmission losses, and possibly higher standby losses, depending on how good your insulation strategy is. Another good thing about remote storage is that you can bypass it when you want to. With large-capacity onboard storage like a Garn, you're in for a long wait if you have a cold house and a cold boiler. On the other hand (sound familiar?) once you get the Garn momentum on your side, you've got a lot of cushion to play with.

 

[jebatty]

This comment is very well taken: "Another good thing about remote storage is that you can bypass it when you want to. With large-capacity onboard storage like a Garn, you’re in for a long wait if you have a cold house and a cold boiler." I have a unit heater loop which by twist of a valve will be fed by the boiler directly for instant, full heat. Another twist and all heat moves to storage, or twist in-between for some to unit heater and some directly to storage.

 

[Tony H]

Great looking place you have there! Great advice as usual!
A couple of thoughts on the garage BR
The clearances for the boiler are from flammable materials so you can go much lower with cinder block just make sure you have room to connect everything and service everything without a problem and of course check the local building codes.
Consider a door to the outside for loading in firewood.
Way in the past I used some vents that were controlled with 120vac so if you check around you can probably find something similar and use the boiler controller plus maybe a relay to open it during system burn time.

 

[rvtgr8]

Eric,
Thanks for the quick return. I was unaware that it was not a pressurized system and that fact essentially eliminates the Garn from my thinking. How about the Tarm 60 with their water storage system? Are they fairly reliable. They do have an outlet in Northern Colorado.

Robert

 

[Eric Johnson]

The Tarm is an excellent gasifier. Basically, the Tarm, EKO and Econoburn (bottom banner) are similar in design and performance, from what I can gather. I seriously considered the Tarm Solo 60, but its max wood length is 20 inches, and all my wood (some 40 full cords) is 24 inches.

A couple more points.....

It's against code to put a wood-fired appliance in an attached garage.

I have about an inch of clearance on either side of my boiler from the cinder block walls, which are filled with vermiculite. On the EKO, all of the regular maintenance/service points are front, back and top. Since I have doors on both ends, access is easy and complete. If I ever had to take the side panels off, however, I'd have to disconnect the piping and pull it back out of there.

 

[jebatty]

Ditto on Tarm -- top, back and front -- Tarm is pressurized. I do use a HX for non-pressurized storage. But need room somewhere for electrical boxes, etc. Obviously much latitude here, but I put electrical boxes on the side because this was convenient in my case. On wood length, 20" for Tarm is true, and I had a fair quantity of wood at 24". Fortunately, I had a pile of logs not yet cut, so making the shift to 20" was not a big deal. I did recut the 24 to 20 and had a lot of small pieces for early season burns.

 

[Eric Johnson]

Yeah, the pressurized/nonpressurized thing becomes kind of a nonissue when you're talking about storage, unless you decide to go with pressurized storage (usually 500- or 1000-gallon LP gas tanks). Otherwise, you're dealing with some sort of heat exchanger at some point anyway. One thing about all that onboard storage with the Garn, however, is that you have to treat the water, and there's a lot of it. With a rubber-lined nonpressurized tank, steel corrosion and boiler integrity in an oxygenated environment is not an issue like it is with an open system like the Garn.

 

[chrisfallis]

I installed a Tarm unti in my basement in 1997 and regretted that I did not have a bunch of hot water storage. There was a lot of user error involved, like stuffing the firebox full of wod on spring and fall days when there was little call for heat. I had a number of instances where the chimney was almost completely blocked by creosote. I also had a large number of cast iron radiators and 5 or 6 inch pipe which contained probably a couple hundred gallons of water. Some morings I would be feeding the fire and hear the circulator pump kick on. All that cool water from upstairs would rush into the boiler and I'd watch the boiler temps go from 180 degrees to about 80 in a matter of 30 seconds. It would be just about this time when we also needed hot water for showers. The spousal acceptance factor for the question "Wadda ya want? Heat or hot water?" was pretty low. We had a natural gas backup in the Tarm, and it would bravely try to add its 100K or less BTU to the water, but it would take hours and hours to warm up our cold house. A big storage tank would have eliminated the smokey standby mode and may have added to my wife's quality of life. We sold the house 4 years later and the new owners switched back to natural gas heat.

Did I mention the fine coat of gray ash all over the basement? And I was humping in garbage can loads of wood from outside and down the stairs on a daily basis. This made me swear to move any future woodburner outside.

I had the pleasure of meeting a Garn dealer in Santa Fe, NM this past October. He showed me a demonstartion unit that was installed outside a local community college. The boiler hadn't been run for a few days so he back fed it from the school's main boiler until it reached 110 degrees. Evidently cold starting these beasts can cause condensation and damage issues, Garn's recommendation is that you warm it up with another boiler or install electric hot water heater elements to keep the temps above the critical level. LThe boiler was insatlled in one half of a shipping container, the other half of the container used for wood storage. My wife immediately niixed the idea of a shipping container in our backyard, but the idea has some other applications. Lighting the unit consisted of tossing a some inch or two diameter sticksin the firebox with a peice of lit newspaper. A few minutes later bigger split logs were added. Since this was a demonstration unit, it was ticked out with recording gear to show heat output. The dealer said that he had no problem extracting the rated BTU output of the boiler, and it was possible, with diligent monitoring, to even surpass it by 10%. There was a bit of smoke roll out when loading, in spite of the iinduced draft fan. Aother reason to keep this outside the living space.

I would like to buy one of these and install it in my detached garage. I still have to quantify my haeting demads, but on cold winter days I use about 1,000,000 BTU per day equivalent of natural gas into a circa 1900 boiler and circa 1940 hot air furnace. I probably am getting 50% efficeincy with these old units, so maybe the heat load is not as ugly as it seems. I think it would be neat to fire a wood boiler like hot holy hell for a few hours and get 1 to 1.5M BTU of heat into storage. I'll take marginal standby losses over constant smoke any day.

 

[Eric Johnson]

Welcome to the Boiler Room, Chris.

Was your Tarm a gasification boiler, or one of the company's standard wood-fired boilers?

The Wife Approval Factor (WAF) heavily influences most of the calculations made around here.

If you had hung a $100 sidearm heat exchanger on your hot water heater, you would have had plenty of hot water, regardless of the state of the boiler.

Glad to have you aboard. Hopefully we can share some ideas and make your second attempt at central hydronic wood heat a more positive one.

 

[ISeeDeadBTUs]

I'm just jealous of Chris' snow. Is it supposed to be 60 In January in NY???

 

[chrisfallis]

The Tarm was a gasification model, and would burn very cleanly as long as it was burning. On idle, though, the firebox and chimney would end up coated with creosote. I suspect that smoke was slipping past the bypass (or loading) damper and hitting a relatively cool chimney (all insulated and all inside the center of the house). We also had to watch for blowback or spontaneous ignition of a firebox full of gas. The owners' manual said to open the bypass damper use the fan to clear the firebox before opening the door in front. Sometimes I forgot and could see the hot coals and rolling clouds of pyrolysis gases when I opened the door. All that was missing was oxygen, which Ihad just introduced. Only quick reflexes kept me from getting facial burns, although a friend lost his eyebrows when he didn't move quickly enough. I usually just slammed the door closed and was rewarded with a whoosh and a puff that made my heart skip a beat or two.

My DHW setup consisted of a coil inside the boiler and my decommissioned gas water heater acting as a storage tank. There was a circulating pump between the boiler and the tank to keep the storage tank temperatures up. If the storage tank temp was low, it would try to draw heat from the boiler coil. If there was no fire (cold night, out of fuel, stupid fire builder) the "hot water" and the boiler could be ambient temperature. I always got up early in the morning, shut off the circulator pump for the radiators, and let the boiler heat up our supply of hot water. 15 minutes or so would be plenty of time. If Momma didn't have hot water for a shower on a winter morning, weren't nobody happy. After showers, I would turn the main circulator on a let the radiators upstairs have a little heat. The house would take a few hours, but would eventually heat up.

I did get a bit tired of the small firebox and the every other hour tending during the winter. OK, maybe I am a bit crazy about the whole wood haeting thing, but I really wanted to sqqeak every possible BTU from the boiler. I think with a bigger firebox and more capacity for heat storage this system would have been more than adequate.

 

[Eric Johnson]

I hear you on momma's hot shower. For me, that's usually Priority One.

I do know that ten years is a long time, and I assume that Tarm and other manufacturers have made significant improvement in gasifier technology since then--especially in the area of idling.

I'm a little confused on your hot water problem. Usually a check valve or flow control valve is all that is needed to keep the hot water in the tank, once it gets in there. And you should have an aquastat hooked up to your pump so that it stops pumping water through the coil as soon as the boiler gets below, say, 140 degrees. Both are cheap and easy to do. As it is, with no storage, I get up to a cold boiler most mornings, and a 50-gallon tank full of hot water. So it's not hard to do (if I can do it, anyone can).

I have an EKO 60, which is very similar in design the Tarm gasifiers, and I don't get any creosote during idle, though I try to idle it as little as possible. I suspect a Tarm Solo 60 is similar, though some people seem to have more trouble with idling than others--with both brands. Here's what I'm heating with a 60kw boiler and around 10 cords of dry hardwood per year.

 

[Reggie Dunlap]

It sounds like something wasn't right if you were getting that much creosote. I checked my chimney today after 3 weeks burning and there was some fly ash but no creoste. You may be right that the bypass damper wasn't fully closed, that would do it.

 

[TCaldwell]

rvtgr8, can i ask why a non pressure boiler is something you want to stay away from? thanks tom

 

[jebatty]

Slow heating, whether Tarm or another gassification boiler, seems principally related to four things: 1) having considerable storage which has fully cooled and feeding the system from storage, 2) having a very large system which has fully cooled (effectively storage), 3) not having a mixing load valve on the boiler, or 4) not having a boiler bypass direct to heating rather than to storage.

I have 800 gallons of non-pressurized water heated through a plate hx; a small system; a mixing loading valve; and bypass to system. I did a self-install, challenging but clearly doable.

My Tarm Solo Plus 40 moves from boiler temp of, say 50, to 150 in about 1/2 hour from a cold start. At 150 my circ pump kicks in. If immediate heat needed, open the bypass valve and 150+ water immediately is into the heating system. As immediate heat not needed, partially close down the bypass, then fully closed, then heat from storage. O do not have DHW installed yet.

It takes about 5 minutes to start a roaring fire with dry kindling and few tied knots of newspaper (top down): firebox closed, damper open, draft fan on, gassification door open. Then shut off fan, open bypass, open firebox, add about 4-5 small splits -- no smoke into room at all. Shut firebox, turn on fan, close gassification door, close damper, let burn for a couple more minutes. Flue temp now at least 300 and climbing. Shut off fan, open damper, open firebox, fully load -- no smoke in room. Close firebox, turn on fan, close damper, enjoy 100% burn until fire burns out -- my hx will draw to storage all the heat the Tarm can produce. A load of pine will last about 3-5 hours, depending on whether it is a first burn or a reload. Rarely will the Tarm reach 190 and shut off and cycle, but if it does, the off time is about 15 minutes. It will almost always hover around 170-180. Thus, no idling. This is the great benefit of sufficient storage with a hx of sufficient capacity. BTW, once the circ pump kicks on, it stays on. This is the benefit of the mixing load valve. The boiler never cools down because of cold return water, the boiler only continues to heat and stays hot until the fire burns out.

It's now 4 months of heating this winter. I burn pine slab wood, full of sap and pitch, but dry (10-15%). Chimney is 4' black stove pipe to ceiling and 18' of stainless, insulated, 6" pipe, through an unheated attic. Top of chimney is 3-4 feet above the roof peak, excellent draft. There is only a fine coating of dust and discoloration on the stainless chimney. No creosote at all. I have not cleaned it. The black stove pipe I have brushed twice but probably would not have needed to do this. A very light layer of ash has accumulated in the black stove pipe.

I found it hard to believe the small quantity of ash produced. 10-12 hours of burning pine will produce about 1-1/2 cups of ash.

Once my storage is up to at least 150, I usually only have to load and fire the boiler once per day. Sometimes a second load is needed if it is really cold, and I try to do this while low coals remain so the fire starts right up. Actually, at this point the refractory remains quite hot, and a burn to gassification is fast.

For a wood burning appliance for the home, I can hardly imagine anything sweeter, easier, cleaner, or smoke free, both inside and outside.

I am certain others with different brands have had similar experiences. Hope this help others who still are learning how to operate their systems, or has a pointer for more experienced users. Send your pointers my way!

 

[Eric Johnson]

You'll have to give us some details of your flat plate hx for charging the tank, Jim. I was planning to do that, but went with a two-part in-tank copper hx instead, but have yet to get it all hooked up. But I am interested in how you engineered it (sorry if you've already explained it in anther post that I missed), since I gave the issue a lot of thought.

Other than that, your experience with the Solo 40 sounds a lot like mine. Like you, I get zero creosote, good gasification quickly and a clean burn in all but early-stage idle. I still can't believe the amount of heat the thing puts out with a small amount of wood, compared to my old Royall conventional indoor boiler.

I've noticed that there are a couple of threshholds with the coal bed. With a good bed of coals, i.e., covering the nozzles, you can just toss a load of wood in and keep right on trucking. With a meager bed of coals, it pays to open the ash door and get a good fire going again before closing the bypass damper and initiating gasification. But all you need to load in is wood. With just a few coals, you need to put in some paper, pine cones, bark, whatever and open the ash door, or you're in for a long wait. I guess I've learned that a gasification nozzle is not a cast iron grate, so it's not as responsive with just a few coals. But I will say that grate or no grate, this is the easiest boiler I've owned to start up from a cold start.

One thing I think I've learned is that everyone's air needs are different. These boilers have factory settings, but you have to adjust them to fit your situation. My boiler smoked some of the time with the factory settings, but since I've opened them up (the secondaries), nothing comes out the stack except white vapor when it's below zero.

 

[TCaldwell]

jebatty, with the garn I daily raise 2,510 gal of water 45+deg representing 940,860btu in under 2.5 hrs, with a partial reload of wood at the 1 hr mark!

 

[Hbbyloggr]

You might also take a look at Emprye. They have an outdoor stand alone gasifier new on the market. We run an Empyre 450 OWB and have had good luck with the quality of construction.

Hbbyloggr

 

[Hbbyloggr]

This is the link to the Empyre ECB. http://www.profab.org/

Hbbyloggr

 

[rvtgr8]

TC,
Perhaps my ignorance is showing, but I was under the impression that it was a somewhat more complicated to use an unpressurized boiler on a pressurerized radiant system such as mine. I know it is not impossible, but I only have a purple belt in plumbing. To further torture this lame analogy, I have found myself in a plumbing dojo filled with blackbelts who actually possess working knowledge of engineering marvels that sport names like Tarm, Garn, Eko, BioMax and the Polish Sausage. I think that last one may not be a gasification unit. I obviously need to do more research. Honestly, the only Garn I had heard of before last November was an alien beast fought by Captain James T. Kirk on the original Star Trek. That is why I am here. I seek enlightenment from the masters. I welcome any and all advice. Am I mistaken about the pressure issue?