Profab 400 Outdoor Wood Boiler

Watching.

This is the same unit I'm looking at.

If you want to compare water content you would be better off comparing boilers of a similar type.

Without knowing anything about these boilers, the primary reason for 400 gallons is that the boiler is likely a conventional, water jacket boiler, aka smoke dragon, and likely about 1/4 to 1/3 the efficiency of a proven design gasification boiler. Similarly, with 100 gallons it is likely that the boiler has added fire tubes through a much smaller water jacket or a water jacket area that does not fully surround the firebox. Depending on the design, it is likely that the 100 gallon boiler is more efficient that the 400 gallon boiler, but it also is likely that operating recommendations also are different. Do your research.

My Tarm, a gasification boiler, has only 54 gallons of water, uses about 1/4 the wood of my old OWB, is nearly smokeless, generates an extremely small quantity of ash as compared to the OWB, and runs circles around the old OWB in performance.

why one hundred gallons instead of 400? haveing had a central boiler and now a gassifyer, i can take some guesses at this. One is that the gassifyers have one hundred percent control over the air supply to the fire, and I notice that the amount of air supplied to the firebox is not excessive. I notice this on a temp gauge i have in the house measuring the incoming line. My old central boiler could easlily raise the temperature 20 degrees in a half hour where my new gasser is much slower. So the increase in temperature is slow compared to a central boilers somewhat uncontrolled air flow. So if its slow and controlled gain in temperature, it would not be good to have really large amounts of water to heat like 400 gallons. I think one reason that they feed a fairly conservative amouint of air to the fire is to make it so it does not all burn at once. Some air is supplied to the first burn chamber and some air is supplied to the secondary gassification chamber. Of course it is enough air for good clean combustion and development of gasses..but its not a runaway fire with all the good burn gasses going up the chimney.

you may say you want the fast increase in temperature, but my new gasser seems to maintain the temperature very consitantly, even with just a few coals in the firebox, it seems to stay steady for a much longer time than the central boiler. Again, with 400 gallons of water, those few coals would not be able to keep that water warm.

these are total guesses at some of the reasoning behind the smaller amount of water.

Great answer barkeatr.

I've been scratchin' my head about this for months ever since a guy down the road picked up a P+M Oprimizer 250 which is an outdoor gasser rated at 180,000 btu's. Comparing it to my Econoburn EBW-200 is like apples and oranges, hard to believe looking at the dimensions that it's supposed to be a comparable sized machine doing the same job. It has 240 gallon water jacket vs. 42 gallons on the EBW-200. The upper fire box (WxHxD) is 28x30x30 compares to 21x29x23 on the EBW-200. Another interesting difference is that the combustion nozzle in the Optimizer 250 is basically a 2"x2" hole located in the floor of the upper combustion chamber which is actually no more than a bed of firebricks. This guy says that he can load his P+M up with 24"x8" rounds and get 12 hour burn times out of it but deep down me thinks he's likely wasting a lot of btu's. My wood is split to about 4" and limited to 18" lengths. Our houses are about the same size and age so it would be interesteing to compare wood consumption, maybe next year we'll actually keep track.

My take on this is that the OWB builders coming to market lately with their new gasifier designs don't really get the science behind it. They're moving in that direction because they know they have to but their doing it grudgingly. For an analogy think of how the N.A. car manufacturers have been trailing the Japanese auto technology for atleast 30 years now. They kind of know that the goal is to maximize efficiency but they can't quite grasp the idea of fuel economy or controlling the burn. Instead of paying attention to what's going on over in Europe in terms of combustion technology they're gazing into the next field trying to emulate the designs of the leader in "farmer's boilers" Central Boiler and figuring out how they can move more "units". Unfortunately they're probably going to lag behind in the efficiency category until they can buy into the idea of paying attention to economy as well.

Not to disparage but I think of these OWB as "farmers boilers" and I suspect that a farmer is probably responsible for designing most of them. They all seem to come out of the upper mid-west after all, including ProFab and P+M. Nothing against farmers but I don't think they're qualified to be dabbling in "rocket science" which is basically what wood gassification is all about IMHO.

Any rebuttals?

interesting. im not 100% sure what your saying, i think your comparing PMs choice to use relatively more water in thier gasser to other gassers companies that have less? My units secondary chamber is also built from bricks, but I dont nessecarily see that as a bad thing, especially after the efficiencies IM seeing and the fact that i can see the gassification happenign in the secondary chamber. I actually would be more nervous about a once piece refractory design since its eventually going to break. I see your theory about generation 1 OWB builders not having the experience..I guess that remains to be seen. We would need someone with more understanding than mine, to answer regarding the choice of the size of water jacket. I know the profab gasser has a smaller water jacket, smaller firebox. Central Boiler had some isses with thier design I guess but to me it looks like a very sophisticaed and highly engineered machine and from what i hear they have that worked out. I suspect they must have had to hire a engineer with experience to design thier unit. I will say my profab will take 6 four to six inch diameter logs and heat my house for eight to twelve hours in 30-40 degree weather and my old CB would have burnt at least twice that much. I asked profab about thier opinion on water storage and they said they didnt need it. Have they figured out a way to idle the machine without excessive creasote? I dont know..probably not.

I will add my 2 cents for what its worth. I replaced my indoor Benjamin wood oil combo boiler with a CB 6048, located outdoors.
The Benjamin had 40 gallons capacity, the CB 6048 has 390 gallons. These are both relatively inefficient boilers and not gassers.
The Benjamin, with small volume of hot water could never keep up with the heat load of our 4000 sq ft home and shop....the cooler return water just could not get hot enough, fast enough to keep the temps in my radiant floors warm enough to satisfy the load. We had to heat by zone with timers to even keep comfortable.
The CB however, with its large capacity, is able to provide enough hot water, 180 degrees, that more than meets our loads...and all our DHW, (Benjamin never did DHW).

In a traditional OWB, water volume means a lot....as there is a temp diverting valve that will start to operate at 160 degrees, and basically shuts any flow into your heating system at 150 degrees, and sends it directly back to the boiler....this is done to prevent shock to boiler...without sufficient capacity, and a high load, your return temps would drop so low that the thermostatic diverter valve will kick in and you will start to diminsh hot water entering the system.

Gassers run on much hotter fire temps and can heat much more consistently. You run short hot fires and utilize all the efficiency thru storage of some means...or you need to run a few short hot fires a day to keep up....

So, gassers with storage or OWB with higher water volume capacity perform to the best of their respective efficiencies. (does depend somewhat on your loads and climate....I am in Northeastern Ontario...and we have long cold winters.

OWB are very common in the rural area I live in....we looked at gassers, but decided on the CB 6048. I know a lot of members here are not big fans of OWB, (smoke dragons), but for us...it is the best solution by far. We have unlimited wood on our property, we get great long burn times, coldest winter days at -30 degrees we stock twice a day, (and we dont fill it up either), at this time of year, we get 24 to 36 hours of burn time....

Our wood usage is not horrible either, maybe 1 cord more than what we used with the Benjamin...so perhaps 8 to 10 cord for a full heating season from September thru to end of May...yup...long heating season eh....

Not only is the wood consumption reasonable, maintenance is low on the CB,, (clean it once a month isntead of every 2 days on the Benjamin), wood handling has been reduced drastically, no more splitting, piling, and hauling and stacking in the shop. Now we just skid our logs right to the boiler location, buck em up, stack en and ready to go....My family and my labor time to process wood for the CB has taken weeks off our wood prep time....weeks

Good luck with your decision...

Mike

Hello wood choopa , The gentlemen that owns the company that sells the vigas is basically a farmer and i think he is on his game when it comes to wood boilers. Ps he also builds planes. So lets not under estimate our farmers.With out them we would all be a bit hungry.

henfruit.

Couple of points.

1. Vigas ain't made around here, I'm specifically referring to a N.A. mindset.
2. Never in my life seen one but I take it that it's a well designed European style indoor wood gasification boiler. Not the type I was referring to.
3. I'll agree with you that farmers should stick to growing food and fixin' thar machinery!
4. Exactly what does "selling boilers" have to do with "ENGINEERING"? Throwing in the word "contraption" just doesn't cut it.

Choppa, My point is that this gentlemen is smart enough to bring one of the best european boilers into this country and understands the quality and efficiny of it to sell it to the american consumer. Farmer or not he is no dumb farmer,but a smart business man.