Help Me Understand and Fix Bridging

[Clarkbug]

Mornin' everyone.

So like most new boiler owners, Im now trying to figure out my system. Moreso today now that there is actual cold weather out there, and the house wants heat.

Most of this week I have had to load the boiler up in the morning, my wife does it again when she is home from work in the evening, and I fill it again before bed. Admittedly, nothing is insulated in my unfinished basement, so I know that I am essentially running three giant 220 gallon radiators all the time. But Im not getting the heat that I would have thought either into the house or into the tanks. Part of it is that Im questioning the dryness of my wood, but the other is that I have found bridging several times when I go check on things. I knock the pile some with the poker, and immediately get the blowtorch noise and see the flue temps shoot up. Seems to be happening fairly frequently, and I think thats where my wood is going. I end up bridging, and it burns, but Im not gasifying like I want to.

How is the best way to avoid this? Im not even sure what makes it happen. Maybe Im filling the firebox too full? The Varm has a single hole in the middle of the refractory, not a long slot like some of the other boilers here I have seen. Will that make a difference?

I know plenty of folks here have dealt with this before, so I welcome your thoughts and suggestions on what I can do to fix it.

 

[Jeff S]

Dry wood is extremly important ,but bridging can also occur if you pack your boiler with an abundance of large splits.

 

[infinitymike]

The wood gun is different in that it has 5 slots down the middle so I may bridge in one area and not another.
However, I have found, at times, full bridging as well.

I'm still trying to figure out the whole thing as well but,

What I've read here is to maintain a thick full bed of coals. After achieving that, lay a nice split right in the center and then a split on the left and right. I just read here that the splits should go with the larger side down and the smaller, pointier side, up.
I also read that using smaller splits will help as well.
Some of mine ( the ones I bought thinking were "seasoned") are quite large. Some are just a half split of a log that was about 6" diameter.Some are even bigger, pie shaped but about 5" at the base and 6" to the point. I've resplit a lot of stuff and it seems to help.

I think that even though we all have the common thread of wood burning, each one of us will find our little niche and style that works best for us.

But, I still love all the helpful little tidbits, ideas and thoughts that have helped me create my own style, (albeit a 3 month old style) :red: still learning.

 

[willworkforwood]

..... Part of it is that Im questioning the dryness of my wood ....I end up bridging, and it burns, but Im not gasifying like I want to. ...

Does that mean you don't know what the MC of the wood is, or that you do know and think it's too high? Split size is important, but if all of your wood is 20% or less (when measured via re-splitting), with a good start it's going to burn fine regardless of size, unless the splits are too long and touch the boiler on both ends. One other thing to realize is that a load of wood is constantly shifting around inside of the chamber. There certainly have to be short periods of time when the wood isn't well-placed over the nozzle. So, at any given moment you could probably "improve" the burn by manually adjusting the wood. But (for well-seasoned wood), if left alone, more will soon drop down to take up the space over the nozzle. If you're seeing large gaps often, then the fire isn't feeding itself properly, which is likely a sign of high MC. So, assuming there isn't really physical bridging taking place, my guess is that the MC of your wood is too high. Also, if the boiler was producing outstanding heat, and the uninsulated tanks and pipes were losing a lot of it, then your basement would be roasting - is that the case?

 

[Clarkbug]

Thank you for the responses everyone.

Most of my splits are fairly small, smaller than I would have used if it were a woodstove. I do have lots of the "deck of cards" splits, but most seem to be a little smaller than a slice of bread. There are the oddballs, of course, and my lengths are all over the place. Nominal is 16" or so, but I had a 12" and a 22" this morning. The long guy wont fit and Ill have to trim it down later.

Part of my problem may be that in the morning, I have been throwing a handful of kindling on, some cardboard scraps, and a few small splits, and hitting it with the torch. As soon as that started going, I had just piled the boiler full since it was burning away. Im now thinking I probably need to wait for those first few small splits to coal up some and then load it up.

I think I also may have been packing things in to tightly, since this morning I have just been setting a few pieces in on top of things, and its been chugging away nicely. Not the best for efficiency, since I keep interrupting the burn and adding "cold" wood, but Im home for the morning and am tinkering.

In regards to my wood moisture, a few of my pieces were re-split and tested with a pro moisture meter, and most were about 22% in the middle. The outsides were around 12%. So a little higher than optimal to be sure. The reason I was concerned about it is that the other night I went to check on it, and there was water bubbling out of the end of one piece. Not good. Plus I will occasionally hear the hiss of steam right after I put a few new splits in. Maybe its just some oddball pieces, but it didnt give me a warm fuzzy feeling.

My basement is very toasty right now, especially given how it normally feels. It has been warming the floors this past week, so I know its dumping a lot of its useful heat to the space, not to my house.

And perhaps the biggest part of this is that I really just want it to work awesome NOW. Its still not insulated, Im not used to what its burning schedule will be or the best way to load it, and in general I dont know whats good, bad, or just acceptable. So its probably mostly impatience on my part, and my eagerness to get it "tweaked" so it runs optimally. I guess I really need to get things insulated and then see how Im actually doing.

Im pretty sure also that my tie-in arrangement to the house is hindering me, but thats another thread....