Log Bridges in outdoor wood boiler

[Bob Lentz]

We are struggling with log bridges - we split logs into halves and sometimes thirds and quarters - end up angular splits. When stacked in the boiler, they can "drop" and wedge themselves creating log bridge that causes the boiler to burn out the coal bed. We have tried laying splits on groups of  4, in  layers perpendicular to each other like a log-cabin stack with some success but it's not perfect. 

Thoughts?

[Tacotodd]

Can you show me a picture of your predicament? Because I'm not sure exactly what what you mean by "burn out the coal bed".

I'm probably not educated enough on your problem, but in my mind, burning 🔥 is what you're trying to achieve. 

I've been wrong before and don't mind admitting it either!

[cutterboy]

 creating log bridge that causes the boiler to burn out the coal bed. 

I don't know what you mean by that.

[thecfarm]

I think he means the wood gets catch up on the sides? and does not fall down and touches the bed of coal and than goes out.
What kind and model OWB do you have?

[E Yoder]

I think he has a downdraft unit, the wood has to fall on the nozzle to burn properly.
Did it just start doing it this year or has this been a problem for years?
If just this year then is guess it's a change in fuel (moisture, wood type, shape) or an airway is clogged making it burn differently. I've never looked in detail at an older CB gasser so I'm a little in the dark on the details of the unit.

[barbender]

I have a Heatmor, and I've had the same thing happen. What Bob is describing is as the wood is consumed in the firebox, sometimes the top layers of wood in the load form a bridge as the lower layers are consumed. The rest of the wood underneath burns as usual, but the wood in the bridge doesn't fall into the coal bed. Basically just half of your charge burns, you go out wondering why the stove went out, open the door, and say "what the heck?" because the bottom of the firebox is empty and the top is full🤷🏽‍♂️

Bob, I don't really have any advice, other than to try to throw the wood in a bit messy. I've only had this issue when burning unsplit softwood rounds. Very uniform, fills the stove up nice and neat. A little too neat.

[PoginyHill]

I've had a similar issue once with my Classic Edge 750. At the time I threw in a bunch of softwood log ends of various diameters and lengths. It was a couple years ago, and I can't remember if I got the "fire is out" message or I noticed the temp didn't come up. That particular instance has not been repeated. I do have some occasions when the wood pile will bridge resulting in a cooler than normal firebox temp (reaction chamber). It'll either take care of itself or I may poke it to cause the bridge to fall.
I don't have a good solution either. I generally don't have problems whether I load with straight wood or a bunch of crooked stuff. It might be that your wood is too long for the depth of the furnace. I think if there is 3-4" of clear space on each end of the wood pile for air to get around, it should allow every thing to burn and eventually the bridge will fall. I think my firebox is 36" deep, but I put in 28" wood max. Most is 24"

[wiam]

I sometimes see it with my CB classic 400. Seems more when I put a lot of bigger chunks in. Seems less if mixing smaller and large chunks.