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.