A friend of mine has an OWB and he has been burning green wood for years. He will get a load of logs in the summer, cut and split and burn in the fall and winter. He had wood left over from last year so this year it is a bit drier than what he has burned in the past. He told me he doesn't like burning dry wood cause he is going thru it faster than when he was burning greener wood. Have any of you made the transition from burning green wood to dry wood? What changes did you make when burning drier wood? Did you find yourself burning more wood? Thanks in advance for your comments.
I don’t have an OWB, so I can’t speak to how it can be controlled. It’s about available energy. Enthalpy and fuel to air ratio. The major point is that it takes energy to bring the water to vapor before it goes away. During that time, the sensible heat doesn’t change. All the energy is used up changing water to steam. Sensible heat being what can be sensed, or felt. Degrees F. So there’s a chit load of burning consumed by the need to change phase of water before the temperature goes up. That process consumes O2 also. Dry wood; less water to have to change phase to vapor or steam. Adjust the damper to match the available fuel, not water, and it’ll go further.
I just talked with my friend and he is running a Central Boiler and it has an automatic damper on it. The only adjustments are to temperature. He has it set to open at 160 and close at 170. Are those good numbers for the damper?
Good question and I’ll correct my thought. Probably don’t need to change the damper set point, just the wood moisture content. 160 might be the right temp.
He has been throwing a few green pieces of wood in to get a longer burn time and have a nice bed of coals at the next reload.
That's what I would do. Try and get a steady clean burn not a roaring inferno. Avoid having more heat available than the capacity of the boiler to absorb it.
I did a quick search and it appears CB has a reputation for fast burning. They offer a chimney restrictor kit to slow things down.
Those old CB's have pretty much a straight shot from the damper plate to the top of the chimney...that's a good thing when burning green wood that needs a lot of air. If he's burning dry wood he might need to add a baffle near the chimney exit to slow down the draft.
I have a feeling that the inside of his firebox is coated with a lot of creasote and I believe someone has said in the past, that stuff can act as an insulator preventing heat getting to the water jacket.
It could still be one of the "conventional" boilers even if it is only a few years old....they haven't changed much over the older ones. It probably has some, but I doubt it is enough to have a noticeable impact on heat transfer.
Would a 10 foot stack be too much that would add a lot of extra draft. How much of a stack is typical?
Yes, this is what I've seen. Remember that Central Boiler used to advertise to use green, unseasoned wood for best results. These restrictors were a way to retrofit these old style central boilers.
Could be too much. Most installs I've seen have a 3' section of pipe, but I've seen some with a lot more (mostly for smoke management).
With it being a mild winter and my continuation of doing tree work; I’ve been burning 95% junk wood this winter (burning live trees I cut down days before, green white pine, rotten wood, etc) and my blower runs way more trying to burn off all the water in the wood to maintain temps. Maintaining a coal bed is a lot harder and I’m feeding it a lot more wood. Any idea that green wood is more efficient is just in your buddy’s head.
I can't speak for a CB, but my EZ boiler is also "old style". Wet/green wood will burn in it, but it's not the way to go. I've got 8' of chimney & the stat is on at 170 & off at 180. To get long burns I just use bigger splits & rounds. Usually 2 years seasoned. Elm & Ash rounds in the 8-12" range X 2' long will last a good long time. I tried some green wood to experiment & it burned it, but the smoke was horrific. I get 12hr burns on 6-8 larger splits all winter. That's approx 1/4 load in relation to a full box. I've never tried stacking it full.
