Just talked with Fred Seton ..

Hey Jimbo,
No rust visible yet. When I burn green wood I will get a few drops of moisture come out each of the back corners. I should start looking for SS sheets soon, I guess. You really do have to operate one of these beasts to understand them. They will burn wood a Euro would choke on.
GW should have mentioned at some point the importance of cleaning the fly ash out of the exhaust outlet and the horizontal stove pipe run. I clean mine twice a season.
Pat

tigermaple said:

GW should have fired that a$$ Dave Barber and spent the money on enhancements.
Pat

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Amen, Brutha :coolsmirk:

sgschwend said:

As to your question about heat loss:

Heat from season cord red oak: 24 M Btu,
Heat to evaporate water 2.1 M Btu
percent heat lost 9-10%

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Further clarification needed Steve . . . . That 'heat to evaporate water' figure . . . is that per percentage of moisure or what?

Kinda funny that they called it the Greenwood!
Talk about truth in advertising.

jimbo,

I used the energy value to evaporate cold water which is 1150 Btu per pound of water, the wood can be cold but not frozen, if so then use 1300 Btu/pound of water.

I looked up the weight of a season cord of wood and then extrapolated the pounds of water. The range I posted was to accommodate how dry is dry.
Here is some table information: 1 cord of Oak 12% MC: 2821 - 3625 40-60% MC: 4450 - 5725

So you take the temperature of your starting condition this helps to find the heat necessary to evaporate the water and multiply by the number of pounds of water you remove (which is based on the difference of starting MC (moisture content) and the final).

just a comment on huffing from someone who has never experienced it, and does not own, and has never seen a greenwood, or seton. ( though, I would like to). It sounds like a similer situation to putting a blower on a street car with mutiple carbs. When they idle they huff because they run rich then lean and back again the longer they idle the more extreme it gets to the point of it sounds like an on off swich being toggled.

Patch53,
It sounds from your discussion with Fred that you're doing everything right and everything is working right. So is your boiler is running well and burning clean now? I had a couple of discussions with him a few years back. I was doing everything OK too. I heard the same comments about storage definitely not being needed or even desirable. Unfortunately the positive reinforcement didn't stop the creosote from forming on my boiler tubes. Fred didn't think it was a big deal. He suggested squirting a little kerosene on the tubes (once furnace is fairly cool) and burning it off. It didn't work. In fact, I tried one of those propane "weed" torches that you connect to a 20lb propane bottle and blasted the hell out of a few spots. Got the tubes hot enough (180deg)to cycle the boiler off, but even that wouldn't burn it off. I think the water in the boiler tubes prevents the creosote from getting hot enough to burn closer than about 1/8", similar to the way water in a copper pipe prevents you from getting it hot enough to sweat a joint. In retrospect, I think my expectations were different. Fred was most likely referring to burning thicker amounts of creosote than I had on my tubes. I know the efficiency drops off dramatically when the tubes build even a thin (1/16' - 1/8" maybe )layer of creosote as can be seen by higher stack temperatures. And even this amount annoyed the hell out of me. You either accept lower efficiency or clean tubes a lot. I think most people don't worry about it and opt for the lower efficiency, judging from some of the pictures I've seen of people's boiler tubes. It also seems like you reach sort of an equilibrium where most of the creosote will burn off, once you've built up an initial 1/8"+ coating on the tubes (and lost some efficiency). But the efficiency was one of the main reasons I bought the boiler

I'm not trying to bad-mouth Fred. I have a lot of respect for him and his invention. I think he's generally a good and honest guy, and genuinely tries to hlep his customers. I also know my boiler is oversized for my house, which created a lot of my problem. I do think maybe the efficiency and performance claims are a little exaggerated relative to real world performance and I also think what goes on inside the boiler during the cycling isn't well understood. I have my own thoughts on the "pyrolysis" and "coking" concepts but that's enough for a separate thread.

My question to other Seton style users: Is there anyone who is a Seton type user out there WITHOUT storage who DOES NOT get creosote on their tubes? Pictures please? Is my experience the exception of the rule?

BTW, here's a link to some info I found on wood combustion that shows the relationship between moisture content and available BTU's/lb wood:
http://www.mha-net.org/docs/v8n2/docs/WDBASICS.pdf

JR

this stove was built and tested around soft wood for a heat source. where fred lives there is no hard wood readily available. ive learned this from speaking to fred and from friends of mine that live in the same town, so with that said i think you could get less build up on the vessel running just soft wood. i burn alot of soft wood and have good results alltough i also have to clean my vessel even though i run wide open for the most part of my burns.

Patch53,
Sounds like you've got a good dry wood supply. That's a great way to start off. I burned 1 yr seasoned rounds my first year and I think it was a contributing factor to my issues. I burn all 2yr+ wood now that was dried outdoors for the first year and inside my woodshed for the second summer. I burn whatever I can scavenge. This year I have an assortment maple, black locust, black walnut, and spruce. At this moment I'm burning two big maple lunkers, about 12-14" in dia. No doubt that's what burns best. I have a whole collection of tube-scraping tools I experimented with to reach from various angles. Just about all I use now is the bottle brush...to dust the ash off the tubes.

patch53 said:

2.beans said:

this stove was built and tested around soft wood for a heat source. where fred lives there is no hard wood readily available. ive learned this from speaking to fred and from friends of mine that live in the same town, so with that said i think you could get less build up on the vessel running just soft wood. i burn alot of soft wood and have good results alltough i also have to clean my vessel even though i run wide open for the most part of my burns.

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Yup, when I first started talking with Fred about building a Seton he said he burns pine in his, mainly because he didn't have many choices, other than perhaps Aspen or spruce. No true hardwood species to speak of in Montana that I know of.

How often do you have to clean the tubes?

Pat

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i clean mine in the spring, this will be my fourth year and i didnt clean it after the first year, so this spring will be my third time. i cut the side panel open for easy access to the bottom of the vessel. i do sometimes through the season clean the ash ash off the tubes that i can reach thru the feed door. the ash can build up in the back also. if that was get get wet with creosote that can also make things rot out real fast.

Beans,
By the time it's that fouled, aren't you losing a whole lot of heat up the stack? That's what I mean about the choice of efficiency or routine tube cleaning. I used to take the back off of mine almost once a month to scrape the rear tubes. I didn't let it get quite as bad as your end of season picture but here's some ball park performance numbers: Before I added storage, when the boiler cycled regularly, I would see average peak stack temperatures of about 500-550deg before the boiler cycled off when the rear tubes were fouled. After cleaning, it would only reach about 400-450F. It was like night and day. With my storage setup, it's easy to calculate BTU/hr transferred to the tank. There is a visible drop in efficiency as ash gathers about on the rear tubes and the air inlet tubes that prewarm the incoming air. I typically charge my tank at about 60K BTU/hr with a 450-500F stack temp. Right after dusting the tubes off, I see about 70KBTU/hr for the first few days.

I think that when efficiency claims of 80-85% are made, calculations are all based on data gathered from clean tubes. But in real life, they don't stay clean very long. Real world efficiency is lower. In that regard, I'm envious of the downdraft boilers since the air-tubes are more easily cleaned. On the positive side though, we don't have to do all that nasty wood splitting that those guys do!!

more heat exchanger than fire space.

I attended a seminar on boilers design last year. The engineer presenting has 30 plus years in combustion design, testing and forensics. While not solid fuel specific he claims boilers soot or plug, even oil and gas fired, when there is too much HX surface for the amount of fire.

I would imagine with solid fuel boilers that formula is hard to predict or engineer to. As the fire size and quality is always changing in a wood boiler.

Owners tell me the large water tube boilers are notorious for soot and creasote issues as the fire box can not support enough "fire" for the amount of HX surface the manufacturers have designed into the equipment.

Soot on the outside, or scale on the inside, even a few thousands of an inch drives the heat exchange efficiency down and perpetuates the sooting or fouling problem.

The solid fuel boiler combustion efficiency tests I have seen are always on new equipment. They measure and control the fuel closely 4" blocks of dry red oak in one case. Be interesting to see the same test performed on the equipment after 6 months or so in typical use. A simple BTU meter would be an easy way to watch those numbers and could be added to any boiler.

hr

BTU meter, is there such a thing?

The way the HX fouls makes me wonder about the fact that a control like a Ladomatt might be a good add-on to these units.
The buildup on the HX has to be due at least in part to a cool hx. Isn't this why the Tarm/Eko etc. use this valve, to keep the hx from having
condensation buildup.

Most gasifiers have some means of regular cleaning of flyash off the HX. The fact that this is not simple (at least for the back of the HX) is a
big flaw, no?

deepheat said:

Congratulations Mole
Your posts are so informative on this style boiler.
Iam tearing my hair out about adding storage.
It is going to be a big project for me & wouldn't
tackle it unless it would solve THE CREASOTED
REAR TUBE PROBLEM

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Thanks, Deepheat. I've sponged so much off of the people here, it's nice to be able to give a little back!

A mixing valve can assure relatively hot water returning to the boiler - say 160 degree or so - instead of 120 degrees. However, the jury is out as to whether either of those temps would discourage creosote formation. After all, both are relatively cool compared to the smoke and fire.

Webmaster said:

A mixing valve can assure relatively hot water returning to the boiler - say 160 degree or so - instead of 120 degrees. However, the jury is out as to whether either of those temps would discourage creosote formation. After all, both are relatively cool compared to the smoke and fire.

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I would assume that the downdraft folks specify them for a reason. I agree that is not much of a temp difference.
The gasifier boiler that I am running has no low temp control and is pumping tank water--as low as 100F through the unit without any buildup,
other than some occasional flyash.

mole said:

Beans,
By the time it's that fouled, aren't you losing a whole lot of heat up the stack? That's what I mean about the choice of efficiency or routine tube cleaning. I used to take the back off of mine almost once a month to scrape the rear tubes. I didn't let it get quite as bad as your end of season picture but here's some ball park performance numbers: Before I added storage, when the boiler cycled regularly, I would see average peak stack temperatures of about 500-550deg before the boiler cycled off when the rear tubes were fouled. After cleaning, it would only reach about 400-450F. It was like night and day. With my storage setup, it's easy to calculate BTU/hr transferred to the tank. There is a visible drop in efficiency as ash gathers about on the rear tubes and the air inlet tubes that prewarm the incoming air. I typically charge my tank at about 60K BTU/hr with a 450-500F stack temp. Right after dusting the tubes off, I see about 70KBTU/hr for the first few days.

I think that when efficiency claims of 80-85% are made, calculations are all based on data gathered from clean tubes. But in real life, they don't stay clean very long. Real world efficiency is lower. In that regard, I'm envious of the downdraft boilers since the air-tubes are more easily cleaned. On the positive side though, we don't have to do all that nasty wood splitting that those guys do!!

Click to expand...

the top left pic is the first time, the second time was alot better top right, so this year im hoping will be even better. im sure my efficiency drops thru the year but this year im burning alot drier wood. im not cutting it out of a frozen pile and throwing it in the boiler.

I run a Greenfire (now called Green Horizon). Very similar to Seton design. Anyway, I have often wondered how the unit and hex would perform if the tubes were totally encased in refractory. It would change the combustion dynamics and I don't know if the hex would be able to extract the btus properly. If the design worked , it certainly would take care of the dirty hex issue...

Sparke, I like how you're thinking... the water vessel cast in the refractory with ceramic/ ?? spacers between pipe and refrac. Was'nt there talk a year or two ago-- using high temp board below the vessel.... I wonder how a layered approach would work-- one on top and one below the vessel. I had issues when cleaning my tubes with a boiler brush--removal of the insulation from the top panel.

I have a homemade Seton. Instead of insulation I used 2" hi-temp refractory board. It works great. The top is a little warm but you can put your hands on the steel. When I made the water vessel, I made an extra plate that the water tubes weld to. The holes are slightly bigger so it can slide back and forth to clean the tubes. Unfortunately, I changed my mind and left it off before I welded it. I should have left it on.

I agree with Webmaster Craig, I have a mixing valve that does not let my return water go below 140. I have ash, soot and some creosote but nothing like the pictures some are posting. Has anyone tried some of the creosote removal products? I have been using Rutlands creosote remover. You sprinkle a scoop full over hot coals maybe once a week. Seems to work. I run a round brush over the tubes in the top and were I can reach in the back and everything just seems to powder and fall off. I often thought about throwing a Chimney sweeping log in their once a week but they are expensive. Rutlands powder was about $6 for a pint size container at ACE hardware. Anybody else tried chemical warfare?