No more bridging in my EKO

[sfriedri]

I have an EKO40 super that has the curved refractory in the primary chamber. The super models also have curved pieces of steel that run along the sides just above the top of the refractory, presumably to protect the upper edge from damage. I'm not sure if the older super models have these pieces of steel or not. In any case, these pieces of steel stick out into the firebox about 1-1/2" from each side.

What I noticed during the first several weeks of using my EKO is that I got a lot of bridging, which caused the unit to produce quite a bit of smoke because there was no coal bed maintained over the nozzle. My wood is not excessively long or large in diameter, but I tried splitting it down finer anyway to see if this would help with the bridging but it did not help. I believe I read on another post that someone thought bridging is not a big deal, because they felt that it did not cause any heat loss if the bridge eventually collapses. I don't agree with this because 1) when a bridge is formed the lack of a coal bed creates much more smoke, so obviously it is burning less efficiently, and 2) there have been a several times when I have had bridges form and the boiler has not been able to get up to its setpoint temperature and even a couple of times where the boiler thought it was out of fuel and shut down.

This was causing me to become quite frustrated, so I had a closer look inside when bridges were formed and noticed in each case that the bridge was supported on the sides from the metal pieces above the refractory. So I shut the boiler down, cleaned the creosote away from around the metal pieces and took them out. The tops of the refractory are about 1/2-3/4" so removing the metal pieces significantly reduces the constriction. I also took my hand grinder and beveled the inside corner of the refractory a little bit to further reduce the ledge that wood could catch on, and to reduce the possibility of damaging the refractory when loading the wood or during operation.

Since removing the metal pieces I have not had a single bridge with no other changes to the wood or the boiler. As far as I was concerned the boiler was operating quite poorly with the metal pieces in place, so the possible risk of reducing the protection to the refractory was worth the gain in making the boiler function better. I have my doubts that the top edge of the refractory will be damaged, because it rests right against the wall of the boiler. I'll report back after a year of operation, but for those of you who are having bridging problems in the EKO super models you may want to consider this option.

 

[sfriedri]

One other thing I forgot to mention is that after reading other posts on bridging I tried loading the wood into my boiler in different ways (looser, more round wood etc) but this did not seem to help with the bridging, and the metal pieces continued to be the support for whatever bridges were formed.

 

[stee6043]

Any chance you could throw some photos at this??

 

[sfriedri]

Any chance you could throw some photos at this??

The boiler is running right now, so I can't show any pictures of the way the inside looks without the metal pieces, but I have attached below a picture of the pieces I described earlier. The picture was taken with the pieces standing on end on the floor - in the boiler firebox they are horizontal running front to back on each side. For those people with these pieces in their EKO they will be easy to see. They slide down into two brackets so that the curved part is just over the top of the refractory and the flat part is against the wall of the boiler. They do not provide any support to the refractory itself. As I said above, it looks like they are just there to deflect any wood from striking the top edge of the refractory. I have forearm length welding gloves that I use to load my firebox, so I never just toss the wood in anyway.

 

[Eric Johnson]

I have the older Super with no metal edges, and I've never had a bridging problem.

 

[barnartist]

I have the older 60 without the metal, and have had the bridging problem. I noticed it today when I saw lots of extra smoke. I would like to try what leaddog has done with the refactory, but was waiting on more reports from him about it. I agree that it does effect performance. I was stuck on a temp today until I opened the door and crashed the bridge party.
I see this happen for me mostly when using alot of hardwoods. I am better these days at preventing it, but it still happens more often that I'd like. I'm just glad I am home much of the time to catch it, but I do sleep through one of my burns each day.
Eric, if you have never bridged, your one up on me man, but more power to ya.

 

[sfriedri]

Any chance you could throw some photos at this??

Well, I let my boiler burn down to just a few coals (less than I would normally have before reloading) and took a picture of the inside. I could not angle the camera to get the entire depth of the firebox, so this just shows the back half. Most of the lower curved part of the refractory is covered in ash and coals. It is hard to see much detail in the picture, but you can see the top edge of the refractory running along the sides. The metal pieces used to run along over top of this edge, and stick in about 1-1/2", so the total restriction from both sides was 3" and this is what my wood was bridging against.

As I said, the top edge of the refractory was about 3/4" wide originally and I put a 45deg bevel on the inside corner along the length of the top edge just so that is was not as sharp, hoping to reduce the chance that wood would get hung up.

 

[Eric Johnson]

I have the older 60 without the metal, and have had the bridging problem. I noticed it today when I saw lots of extra smoke. I would like to try what leaddog has done with the refactory, but was waiting on more reports from him about it. I agree that it does effect performance. I was stuck on a temp today until I opened the door and crashed the bridge party.
I see this happen for me mostly when using alot of hardwoods. I am better these days at preventing it, but it still happens more often that I'd like. I'm just glad I am home much of the time to catch it, but I do sleep through one of my burns each day.
Eric, if you have never bridged, your one up on me man, but more power to ya.

Yeah, but don't you have the older 60 without the curved refractory in the firebox? It's not the Super, in other words, just the plain EKO 60 with the flat bottom (as I recall).

 

[leaddog]

I have had some bridging on my eko-80 but more from coals building in the middle and not letting it fall down on the nozzel. I was wondering how you are loading your wood . Lenght wise or sideways. If sideways it would bridge but I don't see how lenght wise it would get hung up on a inch shelf.
leaddog

 

[barnartist]

Your right Eric. Just the plain Jane with the flat bottom. Thought all the "older" ones were flat.

 

[Eric Johnson]

Well, last year the Super that I have was the "latest and greatest," but apparently they've come out with a newer design. News to me.

 

[barnartist]

I suppose they won't give us much on trade either.

 

[sfriedri]

I have had some bridging on my eko-80 but more from coals building in the middle and not letting it fall down on the nozzel. I was wondering how you are loading your wood . Lenght wise or sideways. If sideways it would bridge but I don't see how lenght wise it would get hung up on a inch shelf.
leaddog

I always load my wood length-wise. The 3" total constriction created by these metal pieces was definitely enough to cause the wood to hang up more often. As I said, I checked when the bridges were formed and you could see that the wood was being supported at the bottom by the metal pieces.

All my wood is hardwood and 75% is splits, so perhaps this also results in a greater chance of bridging. The largest dimension of the splits probably averages about 6 - 7"

 

[Tony H]

I have the super with the metal side panels and have had bridging a few times, so far it appears it was caused by my loading of some longer sticks of wood and them not burning and falling in as I thought thet would. A couple of times they were hung on the metal edges but if they were a bit shorter it would not have happened.

 

[Duetech]

Any chance you could throw some photos at this??

The boiler is running right now, so I can't show any pictures of the way the inside looks without the metal pieces, but I have attached below a picture of the pieces I described earlier. The picture was taken with the pieces standing on end on the floor - in the boiler firebox they are horizontal running front to back on each side. For those people with these pieces in their EKO they will be easy to see. They slide down into two brackets so that the curved part is just over the top of the refractory and the flat part is against the wall of the boiler. They do not provide any support to the refractory itself. As I said above, it looks like they are just there to deflect any wood from striking the top edge of the refractory. I have forearm length welding gloves that I use to load my firebox, so I never just toss the wood in anyway.

I have had some trouble at times with bridging but I continue to use the steel pieces. I just took my plates and compressed the gap so they would not extend out into the fire pit area. They do protect the refractory but I have had some corrosion on the steel pieces as well. I think that they are also there to prevent boiler corrosion as that is where the highest temp in the upper chamber meets the cooler temp of the boiler and condensation is highest and corrosion is most active. $.02