magnumhntr said:
. . . not need to be tended more than once every 10 hours at least. I don’t see the point in having one if it can’t keep going while I’m at work. I see there are some OWB type gasifiers out there, and more coming. So that might be my answer. That being said I think if I had to choose right now, it’d be a Tarm or a EKO for nothing other than the fact everyone that I read about having one has nothing but praise for them.
Chris - we've exchanged some comments and you may have seen some other comments from me. Your knowledge has been very helpful.
I have a Tarm Solo Plus 40 (140,000 btu) with 800 gallons storage, self-installed and put in operation in Sept 07. My satisfaction is well over 90% and still climbing as my experience teaches me the best way to operate the boiler in my circumstances. Have seen many other positive comments on the Eco, but no experience. Tarm in Lyme NH is very helpful, and my dealer was very helpful. Tarm makes larger and smaller units.
The only "negatives" I have, and these could also be positives, is the 20" firebox (19" actually is a better working length because my chainsaw cutting sometimes gets the pieces a little long) and single load burn time 3-5 hours on pine. The shorter length makes the splits very easy to handle and load. Good for the *AF if important. Steel firebox with refractory bottom, so need to be a little careful on first pieces in, but after that little danger of damaging refractory. I don't have oak and therefore have no experience with burn times for oak. It should be longer and therefore produce more heat.
With adequate storage your 10 hour time frame should be no issue. SW MI is more mild than N MN, where I live, so your heat requirement likely is less per sq ft. Say you fire in the morning before taking off for the day, takes about 5-10 minutes, and then fire in the evening when you return. Boiler will burn full bore dumping heat as needed for space heating or to storage. With N MN extreme temps, two firings of pine per day is maximum for me, and so far this heating season, one firing is far more common, and some days I can skip completely.
My "ideal" is to move to 1200 gallons or more of storage, as the boiler clearly has capacity to heat more, and larger storage just provides more flexibility. Would not surprise me that if your bring storage up to 160 or more over the weekend, you may be able to go for several days with no firing at all, depending on weather and your heat requirements.
I would strongly suggest sizing the hx (maybe oversize some) and storage to take the full boiler output to get a continuous burn to the end. Idle time is wasteful. Except as my storage rises above about 130, my full boiler output goes to storage. As storage temp rises, amount of heat the hx can strip off the boiler output reduces, and I do get some idle time at the high end.
P.S. -- it's more than fun to see roaring yellow to blue flame out of the nozzle and then wonder, what happened to all that ash I used to get?