Anyone have any experience with the DEB designed DIY OWB plans?

[missouriPoor_Boy]

New to this site today,I stumbled across this site possibly a little late. Found a deal on someones project that they just quite didn't get finished. A little research revealed that the plans for this particular home brew boiler are being sold on ebay. He has 4 different designs but the one I have is plan #1. Any way I thought it looked like a good deal and have high hopes that this thing will do the trick. All that is left is checcking the thing for leaks and insulate and side it. I am somewhat concerned about the efficiency and consumption as I would like to get the best performance I can out of it. It appears to be a very simple design with a 35 cu ft. fire box and 200 gallon capacity water jacket. In the plans it states that this guy estimates it to be about 125,000 BTU's which I'm certain should fulfill my needs for my 1500 sq ft home and mybe a touch extra. If anybody out there has dealt with this and has any ideas on increasing the efficeincy and minimizing the consumption I'd like to hear them. I think I might have an idea about installing a simple slide in baffle system but am looking for someone with experience that might be able to tell me the pro's and con's of such modifications.

 

[leaddog]

I can't tell for sure but it looks simular to some that I made from some plans off the internet. They worked but only lasted about 4 years before they rusted thru. They rusted at the bottem of the chimney where water and condensation mixed with the creasote. They are also smoke dragons.
Burn DRY wood and only put in as much as you need for a 8 to 12 hr burn. If you fill it it will burn it and as it idles it will SMOKE so try and burn it hot.
Good luck
leaddog

I hope the guy was a very good welder and leaked checked it before he put it together as leaks are VERY hard to reweld once it's put together as they are hard to impsible to get at. Pin holes are easy to get in that much weld. One of the reasons OWB makers go with round designs to get less welds. with the sq it is welded on every seam. I think I used about 33lbs of wire per boiler.

 

[missouriPoor_Boy]

Thanks for your response, I've been thinking pretty hard about this and researching quiet a bit about these outdoor boilers and the smoke/creasote thing that you mentioned is my concern. I live out in the middle of nowhere so I shouldn't bother any neighbors with the smoke issue but from what I understand if you have alot of smoke besides at start up then your not getting max performance out of the furnace. From studying everything I can find on the internet I think I might have some good ideas that I can incorporate in to this design that while it still may not compete with the big name brands on efficency I think it might boost the performance considerably if I'm not over thinking the issue. Please take a look at my drawings and see what you think, will these ideas work?

 

[sdrobertson]

This is the same boiler Leaddog made. Actually he made several and they all rusted in the marked location. The last one is still running but this will probably be the last year. In the enclosed pic you can see the place marked that rusts. The problem is that condensation drips down the chimney and sits on the top plate of steel that holds water above the firebox. If I was to use one again, I would try to set a stainless pan under the chimney to catch any water. Like Leaddog said, they do use allot of wood and the fan doesn't shut closed really well and they are always have smoke coming out of them. With the forced draft, they do recover fast but the sure do eat the wood.

 

[sdrobertson]

Also I forgot but the stoves Leaddog built were from Deb Design but he built a modification that included a water filled baffle as shown in the attached photo. I think it cooled the exhaust down so much that it increased the likelihood that the chimney would get condensation dripping down. I think they may have been to efficient at withdrawing heat from the exhaust. Don't confuse this with being efficient as it is still fire totally surrounded with water so it can never get hot enough to burn cleanly as it cannot burn up the smoke.

 

[missouriPoor_Boy]

Cool, so my starting point this year I should get 4 yrs out of the stove, I guess thats not all that bad for $500. I paid $1400 last year for propane. So do you think adding the additional baffling would do anything to increase the flue temperature? and possibly prolong the rust problem?

 

[sdrobertson]

Cool, so my starting point this year I should get 4 yrs out of the stove, I guess thats not all that bad for $500. I paid $1400 last year for propane. So do you think adding the additional baffling would do anything to increase the flue temperature? and possibly prolong the rust problem?

I think it would do the opposite. The cooler the exhaust, the more chance of condensation. Most OWB boilers that I have seen don't have the water filled smoke chamber that they have in the Deb Design. Most have a small baffle but the chimney is in the back of the boiler instead of forcing the smoke back forward. You can add a small plate with holes in it so you could add a baffle later with a couple bolts, but I would defiantly add a pan under the chimney - if I remember correctly I was taking off the front plate and cleaning out the top chamber every three weeks or so...it does accumulate quite a bit of creosote in a hurry(i.e. to the point of plugging up!!). With the pan you could keep any moisture from resting directly on the boiler steel. I certainly don't want to talk you out of using this boiler, just wanted to let you know our experiences. Like I said, the weak point is under the chimney...keep this solid and it will last longer.

 

[missouriPoor_Boy]

I guess I must be interpreting something wrong I was thinking that by adding the baffleing it would cuase it to hold more heat but what your saying sounds like by me adding the baffling it would cool the flue gasses down even worse?

 

[Mid Michigan]

I built my OWB five years ago. Its still working this year. (Got my fingers crossed). Next year its time for some modern technology as in gassification for me. My exhaust comes out of the back of my stove. One exit high so when I open door smoke doesn't pour out and one low so I can get all I can out of smoke as far as heat. It is amazing and fun to tinker with them and see what the last change did. I get anywhere from 200 deg. to 800 deg. exhaust temps. depending on damper positions and fan speed. At 200 I think all right I am getting all the heat out while making creosote, smoke and how much condensation. At 800 a better burn put how much heat am I wasting? I do have to replace the stove pipe on mine every year. That is getting old. Can't wait until next year and hopefully buy new. This should really bring my wood consumption down.

Good Luck on OWB and try to enjoy!

 

[missouriPoor_Boy]

Maybe reducing the water capacity would allow it to heat up enough?

 

[sdrobertson]

I guess I must be interpreting something wrong I was thinking that by adding the baffleing it would cuase it to hold more heat but what your saying sounds like by me adding the baffling it would cool the flue gasses down even worse?

Adding the baffle will increase the temp in the "firebox" but it will not add to the temp in the "smoke chamber". The lower the baffle, the longer the smoke will stay in the firebox which is good as you will transfer more heat to the water but it will not keep hot temps by the chimney. Think of it this way, with a open fire the heat wants to go directly up and the farther you make the smoke go, the cooler it gets. With the baffle, your adding total "length" the exhaust has to go.

 

[Duetech]

Maybe reducing the water capacity would allow it to heat up enough?

One of the hidden problems with OWB's is they are "open" systems so water evaporates from them on a regular basis. Some systems have an autmatic water level control built in. If you reduce the amount of water capacity you increase the likelyhood of running low on water and overheating and burning a hole in your water jacket so I would not suggest you operate with a lower water capacity unless you have an auto-refill (but then I would recommend that for any owb anyway). Also a smaller water capacity will force the boiler to run more frequently at high output (due to btu loss through heat transfer). It probably is more effective that way but will go through the wood more quickly.

If a mod was done it might be best done with a catalytic addition/conversion.

 

[sgschwend]

Why not just install a wood stove? It meets your price criteria, has the performance, will put out all the heat you need and compared to OWB will not pollute our environment. Just because you don't have neighbors to complain doesn't make it OK, your health matters too.

Or look for a used gasification boiler.

Good luck,

 

[missouriPoor_Boy]

If a mod was done it might be best done with a catalytic addition/conversion.

I was wondering about this, it would increase the flue temp correct?

 

[missouriPoor_Boy]

Why not just install a wood stove? ......Or look for a used gasification boiler.

Good luck,

I like the idea of the OWB away from the house low mess....I've already paid the guy for it, that picture in my first post is the thing on my trailer in my drive the day after I bought it. I did do some research on this thing but didn't really know what I had until I got it home. I got my hands on the plans and they made sense to me looked pretty straight forward but I seen a modification to a OWB that appeared to be a Central Boiler on woodheat.org where the guy added baffling and a draft inducer and he said that the increase in efficiency was substantial. So I though I might play with this and see what I could do with it again I think the price was right for $500 it has never been put in to operation been sitting around for a few years

 

[missouriPoor_Boy]

Adding the baffle will increase the temp in the "firebox" but it will not add to the temp in the "smoke chamber".

I was just curious what are you calling the smoke chamber? where the exhaust comes back to the front before exiting the stack? could this also be called a secondary combustion chamber if I understand correctly if I increase the baffling or add a catylist in this chamber I should be able to increase the temperature enough to burn up the smoke. Please be patient with me while I try to understand why something may or maynot be done to increase the temperature enough to kill the smoke.

 

[sdrobertson]

Adding the baffle will increase the temp in the "firebox" but it will not add to the temp in the "smoke chamber".

I was just curious what are you calling the smoke chamber? where the exhaust comes back to the front before exiting the stack? could this also be called a secondary combustion chamber if I understand correctly if I increase the baffling or add a catylist in this chamber I should be able to increase the temperature enough to burn up the smoke. Please be patient with me while I try to understand why something may or maynot be done to increase the temperature enough to kill the smoke.

Not a problem at all on the patient. I'm calling the smoke chamber the path the smoke takes from the back of the boiler to the front and then up out the chimney. My thoughts on the baffling is that on the one I was burning, I would get allot of creosote built up in a hurry and I'm afraid any additional baffling would only give it something more to grab onto. Plus it would make it even harder to scrap all the creosote off. There isn't much I can think of to make it really anymore efficient. You could lay down some firebrick for the bottom which would insulate the fire from the water in the bottom and maybe line the walls some. I saw the modification your talking about but it was never updated so I don't know if that guy continued using it. If you can figure out how to insulate the actual fire from the water cooled sides and bottom then it may burn hotter and cleaner. Maybe a "box" of some material that will take the heat and then use the baffling your talking about....I would now, while its still new and unburnt weld a couple hooks off the back of the smoke chamber that down the road you could hang a baffle down to make any smoke go down before it enters the smoke chamber...If you want to try baffles in the smoke chamber, make them easily removable in case all they do is catch the creosote.

 

[missouriPoor_Boy]

I wasn't thinking of welding the baffle in the smoke chamber, I thought it might be a good idea to make it removeable so it could be installed and removed through the flue clean out access plate. something like this.....

 

[jebatty]

Somehow I think putting time and effort into the deb designed diy owb is kind of like building a square wheel. Might be some fun, but when done, it won't roll very well, likely will break down in a short time, and will take lots of energy to get it to roll and to keep it rolling.

Most commercial OWBs, except those moving towards gasification technology, at least are round wheels and do roll, although they still take lots of energy to make them work. The gasification boilers not only are round wheels, but have long lasting bearings, spin fast, and take very little energy to keep them rolling at high speed. I'd be inclined to chalk up to experience the diy owb purchase, use it for a boat anchor, and spend time and effort on acquiring a boiler that will provide high performance for 20 years or more.

 

[leaddog]

The last one of these that I built we put fire brick on the sidesto help isolate the fire from the water to help get a hotter fire. It seems to help some. the problem with these is the fire never is able to get hotenough as it is completely surrounded with water. Sort of like trying to solder a copper fitting with a little water in the pipe. it don't make a difference hot much flame you have you can't get it hot enough to solder. Thats why OWB burn with so much smoke, they never get up to the 1100* they need to to burn it completely. If you put in any more bafles you will just take out more heat and make it worse. I know as I build one of the ones with all the baffles and had a condencing pipe.
The best bet is to use fire brick and burn it as hot as you can. Don't fill it any more than you need to and try andburn it with out much idle time. Adding storage would diffinatly help as you could burn it hot and burn up the charge and draw off the storage for the heat. If you can burn the wood in one burn down to the charcoal stage you will have less creasote buildup also.
When you shut it down for the season make sure you clean it very well. spray some oil on the upper chamber, put a pail over the chimney and leave the door open a small amount so air can keep it dry. I think the most damage is done durring the down time.
Start saving your money that you are saving burning wood and put into a fund to by a gasifier. Maybe get your system with storage and when you add the gasifier it will be easier and cheaper as that part will be done.
One other thing. burn dry wood. you will get a hotter fire and have less creasote. DON"T believe the nonsence that you can get more heat out of green wood and an OWB will burn green wood. When wood is 50% moisture you have to eveaporate all that water before you will get one btu out of it. Put a gal of water on your stove and boil it dry and think how much heat it took to boil it off. thats what you are loseing. I saw a vid on the net some place where they took two indentical size pieces of wood one 60% and one 20% and put them on a beam scale. it took 3 liters of water to balance it out.
leaddog

 

[Gooserider]

I would also not expect to get any benefit from installing cats either... While a cat will let you burn the smoke at a slightly lower temperature, it doesn't lower it THAT much, and I would expect that you'd never get the firebox hot enough to actually make the cat light off...

Gooserider

 

[Mid Michigan]

I believe all the statements above about increasing efficiency are true. It will be difficult. I have two dampers a air inlet door, fan and baffles in mine and have adjusted about everything one can adjust. No matter what you do it is still a fireplace with a water jacket around it. Any efficiency improvements will be minor. Like I said before this is the 5th year for mine and it is home made. It is fun to DIY and see a successful system. But, there comes a point where you realize it just can't get much better. I either have a ton of cresole or a red hot stack. Neither are real efficient. I burn 10 pulp cord a wood a year to heat 2500 sq. ft. house that is very well insulated. What is that 30 cord of wood? Also I get all the domestic water I can use. Which in the winter months seems to go up quit substantially because you never run out. Mine gets one fire lit in it and it never goes out for 6 months. I have come to the realization I want more efficiency. I am not getting younger and lets face it, 30 cord of wood is work. How much money and time can one save on firewood with a more efficient stove? Just how long will using say a third of the wood pay back in return? 30 cord of wood cost me $800.00 sitting on the semi truck in 8' lengths. So I save $600.00 a year by going to a gassification stove. 10 years its 6,000.00 plus all the labor and equipment necessary. Its worth thinking about.

 

[rotaxman]

Mid Michigan.....well put and good constructive criticism. I think the boat anchor would probably sink his boat. I'm building my own, fun, inexpensive project but I'm already thinking gassification.
Missouri, did you look at DEB's newer design? The water jacket is half the size and the firebox is smaller, there may be other changes that can help you.
I'd like to hear how your mods work out, if you do make changes.

 

[missouriPoor_Boy]

This has been very enlightening to say the least, while I don't want to reinvent the wheel sometimes its good to go back a revisit an idea just incase there was something there that might have been over looked. Let me see if I got this right we've put a jacket of water around a fire to heat it up but the water prevents the fire from getting hot enough to burn efficiently. So to try to get the fire hot enough to burn efficient we then insulate the fire from the water useing fire brick which in turn defeats the purpose of wraping the firebox with water.
With that said the money spent will go towards my education. I have what I have and I guess I'll just have to make the best of it until this thing rots or I can move up. I whished I'd found this site prior to my venture. So I guess I've got probably 3 or 4 years tinkering, cutting a lot of wood and reading this forum before I make a decision on where to go from here. Thanks guys

 

[sgschwend]

It does look big enough to make a storage tank. Not sure how many gallons it would hold but you might consider just flooding the whole boiler and then you money be put to good use.

As to your last question, the fire needs to be allowed to reach a very high temperature so that the fuel can be decomposed into a gas, the gas needs to be burned and then the resulting heat energy can then be removed by a heat exchanger. A fire surrounded by a water jacket is way too cold (by about 2000 F) to support this process.