There is always talk about not burning junk wood, but is there a real reason. In my old aqua-therm I used to burn empty feed bags, seed bags, building scraps, plywood, anything that fit in the door. This worked especially well in the spring and fall when you needed quick heat for not all day long. So is there a real reason not to or is it just ego to not burn junk in a gasifier.

This can be an emotional topic for some. I think it’s fair to say that you don’t want to burn anything with nasty inorganic chemicals (chlorine compounds, arsenic, heavy metals, and so on). You certainly can burn low quality wood and biomass as long as it’s dry enough. As long as gasification is maintained, anything that’s made of carbon/oxygen/hydrogen/nitrogen is pretty much going to end up fully oxidized.

I’m burning just enough each day to heat my DHW, then I set the aquastat to 100*. Effectivly, the damper is spending about 22 hours a day closed. Though this is less efficient than storage would be, ya gotta use what ya got.

Having said that, I have decided that it’s best to NOT burn junk during these types of runs. I want quick heat, then when the air shuts off I want no smoke. 3 pieces of 1 1/2 - 2” apple, maple, or oak will last 12 hours and run nearly VSF. The GW will actually maintain 160-180* for that whole time. I turn up the aquastat on the inside boiler loop so that we don’t heat exchange.

Short of storage or solar, the only two upgrades I will do that wouldmake this system work better are:

1) Isolate the GW loop so that it doesn’t go through the HX when it’s “off”, and
2) Automate the process so I don’t have to change two aquastats a couple of times every day.

Long story short, I say don’t burn junk wood during the warmer times. If you must burn junk wood, a/k/a Aspen, wait for colder weather, then mix it in at 1:1 or less depending on heat demand.

Good point. I’ve found that I get best performance if I have at least 1/3 of the load consisting of solid dry hardwood. The rest can have some punky stuff, poplar, bark, or whatever, Plywood scraps are fine, but I’d stay away from pressure treated. A few nails doesn’t seem to be a problem, either.

Too much really dry wood (pallet scraps, for instance) can be a problem as it will want to burn too fast.

My burn pattern is short hot fires, burning flat out.

I’ll burn anything that doesn’t smoke. That usually means anything that’s dry. The boiler isn’t fussy about how ugly the wood is, and neither am I.

Well, I AM ugly . . . but not a punk.

But back on topic, somewhat . . .  a guy I work with has a downdraft forced induction OWB (I can’t recall the name) that has a ‘smart fan’. Once the water drpos below 165* the fan shuts off, and I believe it fires up for 5 minutes every hour - even when not calling for heat - to reduce creosote builup and the inevitable ‘cloud’ that accompanies opening a damper after 12 hours on idle.

If money were no object, we could combine all the best features off many of the units out there and produce an awesome wood-fired hydronic.

If morals were no issue, we’d outfit creamatories with heat exchange tubes.

^^^^Morals, schmorals. It’s already being done, as I recall. Hell, why not?

What’s with Eric and the carats? I’m thinking Mrs Johnson has an anniversary coming up