New guy - long post

[sled_mack]

Hello,
I've been lurking for a few days now, and figured I'd get some comments on my system.

Overview:
I've got an EKO 60 in a boiler shed about 150 ft from the house. Also in the shed is a storage tank (non-pressurized) with about 2700 gallons of water in it. Pex underground to the house, where a flat plate heat exchanger is used to heat the existing house oil fired hot water system.

Now for the details:
I've added firebrick to the lower chamber of the boiler to direct as much gas as possible to the front, then along the sides to the rear of the boiler. My unit is 3 years old, so I had to make my own turbulators. I used 3/16" round rods with fender washers bent to 90 degrees and welded to the rod so that the gasses in the tubes see the bottom of a V, each V rotated 90 degrees from the last one. Works really well, suprisingly.

The manifold on the top of the boiler is 1 1/4 in pipe. I've got two UP26-64 pumps pushing into the storage tank. Each pump is on 1 in pipe, goes to 2 hx coils in the tank, flow is from top to bottom. Coils are 3/4 in tubing. I've got manual divert valves from just after the pump to the returnn manifold for cold starts. (There are also hand valves to do all sorts of different things, but this is the steady state config.)

One of the pumps is controlled by the EKO controller. I added an aquastat to control the other. The probe for the aquastat sits right on top of the boiler steel.

I've also added an off delay relay to control burn time. I typically fill the boiler with wood, reset the timer, and let it burn for 4 or 5 hours before just shutting down the EKO controller. The pump with the aquastat protects the boiler from over heating.

I've also got a resistor in parallel with the EKO thermistor to get the controller to burn to hotter temps. I can get my water exit temps up to 200, where as I was only getting about 170 without the resistor.

The storage tank has 4 coils for extracting heat from the tank. Coils are 3/4 in tubing. Flow on these coils is bottom up. Tank is only 5 ft high, so it's hard to maximize stratification.

There is another UP26-64 pump in the basement pulling water from the coils. Originally, I had an OWB and was using a "wrap around" config for the hx. That is still in place, but there is also an hx in the return line to the oil boiler. The pump for the wrap loop only comes on if I can't meet the required temp using the hx in the return pipe.

These two pumps are controlled from a home grown control system. I used an Allen-Bradly PLC to do the outdoor reset and control the pumps. I've also got thermostats with PI control, so I can monitor the % on time for each zone, and bump the reset temp if any zone is running too long.

Heating system within the house is 8 zones plus DHW. All but 2 zones have radiant floor (those will by next winter, also). Radian is staple up with thin plates (read - bent flashing). Most rooms still have the original baseboard - flow is through baseboard then radiant. One room has 3 large castiron radiators - flow is through radiators then radiant. In all cases, baseboard was there first, and left in place in an effort to use the lowest water temps and get the benefit of warm floors.

Typical operation:
Normally, I feed the boiler twice a day, once morning and once night. Using the timer prevents the fire from burning out. That big storage tank allows the boiler to burn flat out until the fire is gone completely if I'm not there to feed it more wood. That got old fast, so the timer was added early on.

Once the tank is up to 180, the system is easy to keep going. If it's warm out, I can get away with only feeding once a day. Or, twice a day and setting the timer for 2 hours and using less wood each time.

Under normal operation, my stack temp is usually about 200 deg F. I can't get any lower without losing a good lower chamber flame.

I'm in my thrid season with this, and really have no complaints. With the current price of oil, I'm sure it will pay itself off this winter.

My post is really looking for comments. If anyone sees anything I'm doing that is wrong, let me know. I know the control systems portions, but nothing of the gassification theory. Anything I know, I learned from the guy who sold me the boiler or from experimenting. I could be missing something big here, and just not have thought of trying it.

At this point, I realize that my biggest improvement would be digging up the pex to the house and adding more insulation. (Right now, it's closed cell foam around each pex, wrapped in foil bubble, in a Central Boiler sleeve to keep water out, in an 8 inch corregated pipe for some additional protection.) But anything I can squeeze out of the system is a help also.

Questions I do have: (I'll post separately if this is too long to get responses)

1. How do I know if the pumps from the boiler to the tank are size properly? I tried two smaller pumps at the beginning of this year, and found that I got less heat transfer per wood used. So, the pumps I have are better than smaller ones. But what if I go bigger? At what point does the return go away? Obviously, this is an expensive experiment, so I'd like some input.

2. I get just a bit of smoke out of my stack. It mostly goes away once the storate tank reaches 180. But, the bottom chamber always has light gray fly ash, not dark and sooty. Is this normal? Could I be better adjusting my air flow? Anyone else with this boiler that has an idea what their air adjustment screws and fan dampers are set for?

Thanks for reading and for any comments you have!

 

[Bartman]

sled_mack,
Welcome to the forum, it's great to have you aboard. It sounds like you've got a great system. Although I don't have a gasification boiler yet, I'm looking into controlling my old NewYorker and oil boiler by PLC myself. We all could use input from you about your system.

 

[Bartman]

Oh yeah, if you have some pics, that would be great.

 

[wdc1160]

I think you have a sophisticated enought system to warrant a some type of logging.

Check out Nofo's site. nofosil.org
He is a logging and analysis wizard for sure.

 

[Eric Johnson]

Hi sled-mack. Thanks for sharing. Sounds to me like you've got a pretty good handle on your system. I like the timer idea a lot. You're getting about the lowest stack temps I've seen. You definitely don't want to go any lower than 200, or you risk condensation. How do you control the temp?

I found that I had to take my secondary air controls out a full 6 turns to eliminate the smoke on my 60. It was intermittent at the factory setting of 3.5 turns, but backing them out a few extra turns solved the problem. I glued modified (shorteded) wire nuts to the threaded rods that comprise the secondary air adjustment so that I could play around with them more easily. If the problem persists, you might need to open your primary air controls a bit. They're behind the plate that the blowers are mounted on, in the upper corners. I keep the sliders on the blowers at about an inch. The dealer said to open them up as the weather gets colder.

Your ash sounds fine. Fine, gray ash is what I get, too. Even better is powdery white ash, but I've never seen that, perhaps because I've never really run my boiler at capacity.

You can buy a new controller for the EKO that reads out in F. and allows actual settings up to 195 degrees. It may not be worth $250 to you, as you appear to have a pretty good handle on your controls, but it's nice to see the company continuing to make adjustments for the North American market. That tells me they're serious about the future.

 

[sled_mack]

Bartman,
The PLC is a MicroLogix 1200. Chosen because I could get it cheap off eBay, I had the programming software/cable available from work, and I am familiar with programming it. Any brand with analog I/O will do the job.

For temp sensing, I am using thermistors. I had to set up voltage divider circuits to get the changing resistance to read as changing voltage from 0 to 10 VDC. Took a bit of experimenting to get the scaling right, but it works fairly well. Also, getting good contact to the pile was a challenge. I had to use thermal conductive paste between the pipe and the thermistor, wrap it tightly in electrical tape to eliminate drafts, put a hose clamp on to hold it tight, then wrap in pipe insulation and tape some more.

The discrete inputs are 120 VAC, so I used the hot wire from the circulator pumps wired to the inputs for pump running feedback. I found that one zone is always calling for the most heat, so I only monitor the on time of that zone. The thermostat is set for a 20 minute cycle time. I use a linear scale to add 0 to 10 degs to the reset temp once the zone is on between 70 and 100%. Seems to work well. Lots of solar gain in this zone and lots of loss out the A-frame ceiling/roof. During the day, the on time is low, at night it runs about 60 to 80%. Not bad, considering 50% is ideal in the controls world and 100% would be ideal for heating/comfort as long as it maintained the set temp.

I use a relay to break the signal from the zone control board to the boiler. When the water from the storage tank is no longer able to heat the house, the pump drawing from the tank is turned off and the boiler is enabled. Selector switches allow the system to be put in manual and enable the boiler all/none of the time, and the same for the pump.

The water temp is maintained by just using a hysterisis loop around the reset setpoint. I'll let it get 5 deg above setpoint, then stop the pump from the storage tank, then let it get 5 deg below setpoint before turning the pump back on. Not real tight control, but it works and doesn't slam the pump on/off as often as a tighter loop would.

I monitor the water temp from the storage tank. If it's too far below the reset temp setpoint, I'll switch to oil. I also have an aquastat in the tank that is set for 140. If the water gets below that, I switch to oil also. The aquastat was in place before the PLC, and was used because I didn't want to run out of DHW. I've got to rethink that logic a bit now. There is still usable heat in the tank for heating the house, just not for DHW. DHW is a priority zone, so I can switch to oil for that and back to the storage tank for heating the house. I just need to put some time into thinking more about those transitions.

Anything I missed that you wanted to know more about?

 

[sled_mack]

Eric,
The timer was the idea that saved the boiler. I was frustrated with it always burning out. It seems to me that blowing cold air into it when it is out of wood is a bad idea. And it takes a long time for it to figure out that there is no more wood. Granted, some of the wood in there smodlers, causing a loss of efficiency, but I don't think it's too bad. Once the fire has burned down far enough, the coals seem to collapse when the fans stop and sort of seal off the chamber nicely. To restart, I just rake the coals, put more wood on, start it up and open the dampers on the fans about half way for about 20 minutes. This gets the fire going and heats up the lower chamber so that I can close the fan dampers to about 1/4 open and it keeps a good fire going. I've found that getting the fire a little extra hot at the beginning, then shutting it down a bit, makes a big difference in how the fire will burn for the next 4 hours.

I don't have any automated means of controling my stack temp. I simply adjust the opening of the fan dampers and let it go.

But, it sounds like I may have some adjusting to do there? I'm only open about 3 turns. At the same time, my fan damper is only open about 1/4 of the full 90 degrees, so maybe 5/8 of an inch. I didn't even know there were adjustments for the primary air behind the cover - I've never had the cover off.

It's all a delicate balance. What ever I do, I want to try to keep the fan dampers from being open too much. Burning it hotter and faster will just mean more up the stack if I can't move it to the storage tanks fast enough. Eliminating smoke means a cleaner, more efficient burn. But if I'm losing more heat up the stack, my overall efficiency of BTUs from wood to storage tank may end up being reduced. Is that logic right?

 

[Eric Johnson]

Well, here's what it looks like under the hood. You might find the secondary air control to be an interesting design.

As long as you can monitor your stack temps, I think it's safe to experiment with the secondary air controls. Note that it's not a one-per-nozzle situation. The nozzles get air from both the right and left sides. I think every installation is going to require different settings, since the air supply, etc. are all going to vary. In my limited experience, the way to get rid of smoke (assuming you have dry wood) is by increasing the secondary air. Wet or green wood is going to produce a thin stream of blue smoke no matter what you do, especially if you use it to try to get gasification going.

Your theory on the relationship between air supply and efficiency sounds as good as any other I've heard. I don't think anyone has completely figured that out, at least not that I've seen. But we've got guys "working on it"--the Boiler Room Data Geek Squad is on the case.

 

[sled_mack]

Eric,

You've got a 60, so I'm curious what size pump you have circulating through it? Also, are you pushing or pulling? In my case I'm pulling. Considering the options I wanted to have for valving to the house directly, coming back through the tank, simultaneous feed to both, and on, and on, I couldn't find a good way to push through the boiler, so I had to pull.

Head pressure is everything for the flow rates on these pumps. Each pump is in a 1 inch line. Pushes through about 15 ft of 1 inch copper to a T which then reduces to 3/4 inch. Each 3/4 inch leg is a 60 ft coil for the hx. Then T to 1 in copper for another 15 ft, and T into the 1 1/4 black pipe return. Pressure should be low, and GPM should be high. I think.....

Also, if you are considering a timer, be very CAREFUL You need to have an aquastat to turn on the pump to prevent over heating the boiler. The smoldering hot coals are enough to boil the water in the jacket above the upper chamber without the pump coming on once in a while. It really does work great, and I wouldn't be without the timer, but you need the aquastat.

 

[sled_mack]

Another question...

Barnartist and I have been trying to help each other for quite a while now. (Zenon introduced us.)

He tells me he is considering blocking off one nozzle. Makes sense if he is idling too much. But I have some questions about how that works, and if it might help me as well.

If you block off one nozzle from the top, so all primary air is now forced out one nozzle. But the secondary air is still going out both nozzles. How do you balance for that? Open the secondaries more? Close off the primaries by half? It seems to me this would be quite an upset to a delicate balance, no?

Furthermore, I've got a decent channel that forces all hot gasses from the rear nozzle past the front nozzle, then around to the sides and to the back. If I were to block one channel off, it seems it should be the front one. The fire from the back nozzle would have more combustion time, and would get additional heated air from the front nozzle if it could use it. Am I on the right track here?

Option 2 would be to force all gas from the front nozzle to the back, then to the left side of the chamber such that it has to come to the front. The front of the channel would be closed off, so this air stream would pass in front of the channel and along the right side of the boiler to reach the back. That's quite a rat's maze, and I think it would take some custom refractory, not just my store bought fire bricks.

Finally, would this buy me anything? It seems as though the temp rise across the boiler is the same regardless of having one or both pumps running, a slight difference at best. So, if blocking one nozzle doubles my burn time without reducing the water outlet temp by too much, I may be able to extract more BTUs to the storage tank per wood consumed. Am I on the right track here? Or am I missing something? Since I've only burned about 2 cords of wood this year so far, I'm not in a rush to make changes that could make things worse.

Is anyone actually doing this? It seems that the wood that is away from the nozzle isn't going to burn very well, and may not "fall" into the coals of the fire as the fire burns down. So it might be a way for me to get more heat per wood consumed, but not neccessarily significantly longer burn times.

Thanks for all the feedback so far!

 

[Eric Johnson]

I have a Grundfos 26-96 on one 1" return line (200' loop) and a Taco 007 on another 3/4-inch return line (100 ft loop to the greenhouse) and another 007 circulating supply water into the return through the cooler parts of the heating cycle.

Current theory dictates putting your pumps on the supply lines and "pumping away" from the boiler, but I'm an old-school "cooler water is better for the pump" kind of guy, so that's how I piped mine. At the moment I'm having a problem with the 3/4-inch line. It's either a bad airlock or a bad pump. I think the 007 might be undersized for the job, so it may well be the latter. I don't think the 1" line has enough capacity to transfer all the heat that boiler is capable of producing, though I doubt I've ever run it at capacity, at least not for any extended period.

I like the timer idea, but have my hands full trying to get my storage and some other loose ends tied up this season. Hopefully next winter I'll have the time and experience with this rig to experiment some more. I assume my 200-degree overheat aquastat would handle any overheat problems encountered, although my main pump is set up to run at any return temp over 160, so it should dissipate the heat regardless of whether the blowers are running or not.

Do you recommend shutting off the circulation along with the blowers when the timer kicks off? That would help the boiler retain heat, but the downside, as we've discussed, is the potential for overheating.

 

[sled_mack]

Hmmm... my 64 is smaller than your 96, but the second 64 is bigger than your 007s. Probably, about the same capacity if all pumps are on. Still wondering if more would be better?

I use the timer to cut power to the controller. But, I had the aquastat installed before the timer. If I didn't have the aquastat at the time, I probably would have just put the timer relay contacts in series with the power to the fans. Same affect, but keeps control of the circulator.

Edit to clarify: Yes, I do recommend shutting down the circulators when the timer shuts down the boiler. Keeping the upper chamber hot, results in a much quicker firing at the next load. All you need is over heat protection.

My original thought was to use only one pump till the boiler got hot, then have the second pump start up at higher temps. For the most part, that works, but it doesn't warm up that much faster with only 1 pump.

I'm actually going to rewire the relays that control the pumps so that both pumps run if either the controller OR the aquastat are calling for circulation. I think it will transfer more heat, and give me some redundancy should one pump fail.

 

[sled_mack]

OK, I opened the secondary air screws 3/4 turn each when I started the fire tonight. No visible difference in lower chamber flame or stack temp. Maybe more tomorrow.

But, I have this question - How do you distinguish between smoke and just water vapor/steam coming out the stack? If the weather conditions are right, I got virtually no smoke. Tonight, it's very damp outside, and I have a light, whispy smoke. But when the wind blows it down to the ground, it has no odor, no smokey smell to it. If I open the lower chamber, there is no smoke apparent and no odor from that either.

So, if my lower chamber and my stack don't have dark colored build up, do I have a smoke issue? Or is it just water vapor from wood that is not dry enough?

I do have some pine that I am mixing in. I just started this week. It is left over from last winter. Hard to refuse - it was cut to firewood length, delivered and stacked next to my wood pile for free. It was a bit green last year, drier this year, except it is not covered like my good wood, so it is damp from snow on it. Leaving it sit in the boiler shed for 24 hours gets most of that surface dampness off. As long as I mix it in at less than 35% per load, I don't notice any difference. Mix in too much, and everything falls apart.

 

[Eric Johnson]

I get steam and vapor when it's below zero. Other than that, nothing except when it's getting up to temp. I noticed that unlike tuning a carburetor, you don't see immediate results when you change the secondary air settings. I don't know why. I would suggest opening them up to 5 or 6 full turns and running for a cycle or a day or two. I think you'll notice the absence of smoke. There's an optimum setting for your installation--you just have to find it.

Even when these boilers are smoking, it's nothing like the smoke I used to get with my old smoke dragon. Usually, about all I get for smell is kind of a toasted wood smell.

I think the lighter the ash and deposits on the lower chamber door and reflective bricks, the better. Darker deposits imply incomplete combustion. It's one good way to monitor how things are going.

Getting back to smoke for a minute: Before I adjusted my secondary air, I couldn't tell from looking at the gasification flame that there was smoke coming out of the chimney, because it was just full of yellow, orange and occasionally blue flame. It looked complete, but it wasn't.

On the vapor, I've noticed that in very cold weather, you get the vapor during the first half of the burn cycle. I think that's the water vapor coming off the wood, which you have to remember, has between 20 and 30 percent moisture content (relative to the weight of the wood). When you get a ways into the cycle, however, the vapor disappears. My guess is that most of the water has steamed off, and now your boiler is working with dry fuel. That's another good argument for increasing efficiency by filling the firebox up as much as possible. Otherwise (like me), you're constantly introducing smaller loads and the resulting need to burn off the water. Come to think of it, maybe that's not the case, but it sure sounded good.

 

[leaddog]

Hello,

Now for the details:
I've added firebrick to the lower chamber of the boiler to direct as much gas as possible to the front, then along the sides to the rear of the boiler. My unit is 3 years old, so I had to make my own turbulators. I used 3/16" round rods with fender washers bent to 90 degrees and welded to the rod so that the gasses in the tubes see the bottom of a V, each V rotated 90 degrees from the last one. Works really well, suprisingly.

!

It sounds like you changed the refractory brick in the bottem from the factory ones. Just what did you do. Pic's would help. Nofossel did something like that but his would burn out after time. What are you using. I'm sure that any time you can keep the gasses mixing with air and burning it will help. with both nozzels having the gasses directed into the same chamber it might help getting them to fire sooner. thanks
leaddog

 

[sled_mack]

Eric,

I was at 3 turns, and thougth I'd go out slowly till I get to 5 or 6. I let it go for about 2 hours before going out and looking at it, to give it time to settle in. I'll go to 4.5 turns tomorrow morning and see what happens. Since I'm not in a bad situation right now, small steps are better.

Leaddog,
The factory blocks are under the nozzles. (Oddly enough, I only got 2 with my 60 - some people got 3?) The curved refractory that came with the boiler is at the very back of the chamber, cupped forward. The U shapped refractory slides back almost against it. There is about a 2 inch gap between the rear and front U shape peices. Along the sides of the U shaped pieces I've got firebricks standing on end, flat side against the U pieces. The top of the fire brick is almost touching the top of the chamber. This acts to seal off the "tunnel" in the U shaped pieces so that the fire can not go directly to the back of the chamber or to the sides of the chamber - everything comes to the front. The fire bricks stop at the end of the front U piece to allow the gasses room to wrap around to the sides.

I couldn't get tall enough fire bricks, so I had to lay some down flat and set the others on top of those. Looking in from the front, they look like bookends on either side of the U pieces.

However, this winter I've had some chunks fall off of my U shape pieces. And, I've had a few chunks fall from the ceiling of the lower chamber, around the nozzle opening. So far, no effect on the operation of the boiler. But I don't know if there will be if more falls off, or what I could/would do about it?

I'd like to know more about what nofossil has done in the lower chamber. I saw a pic in a post, but a diagram would be really helpful. I'm going to have to buy some refractory pieces for next season, or try casting some, if the U pieces keep crumbling.

I expect to be cleaning it out this weekend. Should be a good time to get some pics.

 

[leaddog]

Thanks, That explains it well. Dave at cozyheat said the u-bricks a avilable and not very expensive but I don't know how much. Also the nozzels can be replaced also. did you find that when you added the fire brick that it was easier to get it into gasification or that you got a better burn? My eko80 has 4 u-bricks, and they don't have the curved bricks any more. I wonder why they changed.
leaddog

 

[Eric Johnson]

Yes, the two blocks and the curved bricks in the back is the old style for the 60. The new ones have three u-shaped blocks stacked end to end and no curved refractory pieces at the back. You can buy new blocks from Zenon at newhorizoncorp.com. He's the importer. On his website is says that nozzles cost $50 each to replace, so I bet the bricks are less than that. Nofossil has an older thread (towards the bottom of the pile) detailing his labyrinth design. Do a search for "labyrinth" and you'll find it. There are some pics that show pretty much how it is (was--that one died) built.

You're probably less than 2 hours down Route 12 from me. It's gonna be cold this weekend.

 

[Bartman]

Wow, I work late one night and miss all the conversation.

Sled_mack, the Micrologix 1200 was what I was originally looking for, but every time I bid, I got outbid. When I missed the bidding, the PLC went cheap. Ended up buying a GE/TI/Siemens PLC (305/Series1), I've had experience with a couple of these 15yrs ago. What I do like about this one, even though it's old, is that I can have different types of inputs and outputs depending on which modules are used. For temp control interface I'm using digital temp controllers with K type thermocouples. On eBay there are some neat ones, I'm trying one that is threaded so I'll drill and tap the boiler water jacket(s), and possibly monitor individual zone supply and return temps.

What are the forecasted temps for you northern guys this weekend?

 

[Eric Johnson]

It's supposed to get up to 10 degrees for a high on Sunday, along with lake effect snow. The guy on the tube tonight said we're in for a pretty long cold stretch--up to 2 weeks, which is probably longer than those guys can actually predict with any accuracy. But I think we're going to be giving the old heating systems a good run here at least over the next week. Up in the Adirondacks it's usually about 10 degrees colder than down here in the valley. But we do get our share.

 

[barnartist]

Cant' help but jump in. Sled Mack, after my first day of blocking off the rear nossil with a big piece of flat scrap metal, the results were really, really good. I am trying not to get too excited early, but I was able to go longer on a load on a colder day than on a warmer one. Now, I have been burning allot of cherry, and Im into my best section of my wood where some oak lives. Mybe this efected it too, but it was still a heavy cherry mix. Today I was able to turn my fan openings almost shut and still have a nice small flame at the bottom-just enough heat to keep everything going at a real steady pace. I fired at 930 this morning and was able maintain heat till 10:30. I went out and had a nice coalbed left for the next load. Nice colored ashes in bottom chamber. All of the upper chambers wood burned, even in the rear where the nossil was blocked. I did not stuff the box full, as the rear of the chamber only half to the top. Tonight I gambled and started the burn with the fan openings in that same position. I wasnt sure how this would take off-but as I sit here and type, I am watching my water temp with a wireless setup, and it bounced down about 10 degrees, and slowly starting to climb. Nice and slow. I think it will probably idle still early in the morning, whitch might mean I need to let the sto tank get colder- but without a timer setup, I really want some good coals for that next load of wood. I hope this is the berry's- I think you mentioned about the nossil cover to me Eric.

Funny thing about that, there is something to be said about the heated air-I had some flame early in my burn coming from that rear nossil still. But none now. Maybe some ash sealed off extra air. I am thinking though I may need a better way to use 1 or 2 nossils on demand besides covering up the whole. Also was able to maintain 300-325 stack. Im not sure I could have shut the covers any more and have it still function. I still think it would be nice to gear it down a speed at a certain part of the burn cycle.

 

[barnartist]

Steve, is it at all possible that setting up the bottom chamber like that caused the re-factory to fail from more heat consentration? Also, does adding insulation to the bottom of the eko help? Our cat loves that spot. I don't know how his hairs aren't singed- its really hot there. I had some fiberglass under there last season, I am thinking about sealing off all that free air space at the bottom, and either insulating it, or "ducting" it (no fan) to my garage (only a wall seperates it)
I followed Erics advice on the nozzle adjust and turned them out to 6 turns cold turkey. Im not sure what it did but they have been there now for a week.
By the way-2 hours since 2nd load of trial. I am watching the water temp yo-yo slowly about 4 degrees.

 

[sled_mack]

Don't you guys sleep?

Leaddog,
You could just use some flat firebricks to block off the back of the "tunnel" and force the gas forward. I used the curved piece because it was there. I added that early on, when I was having problems and on the phone daily with Zenon trying to get this thing to work. It all sort of came together at the same time, so it's hard for me to say for sure that any one thing made a big difference over anything else in terms of getting the fire going. But, it certainly makes sense to me that the boiler can extract more heat from the gasses the longer they are in the chamber. How much I can't say, but I'm going to leave them in there for now.

Eric,
2 hours north of me puts you just south of Tug Hill, right? We go up there snowmobiling a few times a year - snow permitting, of course. Haven't looked at a map to see exactly where Clinton is.
I'll have to check out the size for replacing nozzles. Hopefully, it isn't the bottom of my nozzle that has fallen apart. And offhand, I can't see how they would be easily replaced. Maybe if I see what he is selling it will be more clear.

Bartman,
The 1200 can take add-on I/O modules. So it works for here. The PLC you have is fine, too. Just make sure you can get programming software and that it works with windows or you have an old DOS laptop laying around. We had to work on an old PLC last year, and luckily, one of my coworkes had an old, old laptop laying around that still ran DOS. Otherwise, our client would have been buying a new processor....
I've never seen thermocouples or RTDs last very long in direct contact with water. You can usually find threaded wells for not a lot of money. Well worth the cost in my opinion. Welded ones are even cheaper, if you are willing to weld on your boiler. I've welded a lot of things over the years, but I'd probably go with a threaded well on my boiler.

Barnartist,
Glad to hear the blocked nozzle is working for you. Oddly enough, last night I was thinking it would be nice if it were easy to block/unblock that nozzle. When we've been gone for a few days and the house is cold, and the storage tank is cold, I'd want to use both nozzles till I get the house recovered and the tank at least partially recovered. But then how to block off the nozzle when it's full of hot coals and ashes? I really don't see an easy way of doing it other than shoveling the ashes out and putting the firebricks in place.

I don't think there is any harm in insulating under the boiler. I don't know that there is much to gain from it, either? I don't think the water jacket goes down there, it's just a bed of refractory at the bottom. How well is your shed insulated? Mine is insulated fairly well, and it gets hot in there. I've thought about getting some of the blue foam insulation board, 2 inch thick, and basically wrapping the boiler in it everywhere except the front. That little bit of glass in the cover of the boiler probably isn't doing much. And it made a huge difference when I wrapped the outlet pipe off the top of the boiler in 6 inch glass. The tank got hotter much quicker, and the shed temp went down a good 10 or 15 degrees. I went right over the pipe insulation that was already on the pipe with the glass.

It is possible that the tunnel I created led to the ruin of the upper refractory. But I don't think it should have. If I left the fire going with the fan dampers all the way open, getting super hot temps in the lower chamber, then maybe. But I'm always keeping it as low as possible and still firing nicely in the lower chamber.

I'm not sure that slowing the fans down is a good idea. You need some pressure behind the air. Even though you are restricting the flow, if something at the nozzle tries to blow back towards the fan, the pressure from the fan will resist that tendency. Again, that's just me guessing on this one.

I opened the secondary screws another 3/4 turn this morning - I'm at 4.5 turns now. It's only a little over an hour into it's burn cycle, so I'll wait a while to go check on it.

 

[Eric Johnson]

I'm just south of Utica, so it's probably less than 2 hours.

To block off the nozzle, you need to clear it off and put a firebrick over the top of the nozzle. Then you have to be careful not to knock it out of place when you load wood. But it effectively cuts the output of the boiler in half, so you can get a harder working fire that lasts longer and puts out less heat if your boiler idles a lot. It wasn't my idea. One of our Michigan EKO members (leaddog, maybe) came up with it. I tried it for awhile and was pleased with the results. As I learned a bit more about how to operate the boiler in my situation. I can't see what it would hurt, though you might have to fool around with the air controls to optimize it.

I think the nozzles just drop into the refractory mass. I've never seen them out of there, but that's what it looks like to me. You can replace the entire refractory mass. It's probably pretty heavy. You have to grind the tack welds off of the secondary air supply tubes and pull them out before removing the refractory.

Personally, I think you take a risk when you try to improve the efficiency of these boilers by modifying the path of the flame. I suspect they designed the refractory that the flame blows into the way they did for a reason. If you look at virtually any Euro downdraft gasifier (EKO, Econoburn, Atmos, BioMax, Tarm, etc.) they all feature some variation on the curved refractory theme. And if you look at the evolution of the EKO design in this area, it's changed over time--but it's always been a curved piece of ceramic. I suspect that deflecting the flame back up into the refractory mass is an important part of the design. And while I understand the reason for creating a design that keeps the hot gas in the bottom chamber longer, I wonder why nobody designs a stock piece that does that.

I guess ditto with the blowers. They've got variable speed fans already. Seems to me if they could easily increase efficiency by varying fan speeds depending on boiler water or stack temp, they'd do it. But I admire you guys pushing the envelope for the benefit of humanity. If I had the technical expertise (which I don't), I might be tempted get into it myself.

 

[barnartist]

Steve, when you say you inulated the output, do you mean the few inched of the flange area? It really made a noticable difference ay? I only have about 6 inches exposed. My shed is not insulted, pretty open really. Air can blow through there. I have thought of insulating that area-is your big tank insulated? Is the heat coming from that or mostly from the eko you think?
Last night I think I choked the boiler too much as is was just enough air to keep up. Seemed like I used more wood, but I don't know if I went idle or not and it just had trouble bouncing back. I know yesterday, I started with the opening bigger like how you do. While last night I let it go from the beggining closed to a minimum.
I like your idea too with the foam boards.