I have an outdoor wood furnace that circulates to a closed-loop heat exchanger. Boiler water is heated from this exchanger with a Taco circ pump on the boiler. My problem is that my Honeywell 8124 Triple Aquastat doesn't seem to allow setting the hi and lo limit switches far enough to keep the oil burner from turning on. Almost all wood burning furnace manufacturers say to just set the low limit switch to 10 degrees lower than the temp of the water at the heat exchanger, i.e., the thermocouple should always sense that water temp is high enough to keep burner off but circ pump should still come on to push hot water through the zones. In theory this must work but with this aquastat it doesn't. I have to literally pull the wire off the circuit bd that goes to the burner to keep the burner from coming on. This is fine as long as I'm not away long enough for the outdoor furnace to go out, example: vacation. However, I'm looking for a better solution. I could eliminate the need to use the tankless domestic hot water option because the outdoor furnace provides plenty of hot water through another small heat exchanger at the tank input. I'd rather not buy another aquastat if possible. To summarize: regardless of how I set the hi limit, lo limit, and differential settings, the burner comes on. Thanks for any help.
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Aquastat and outdoor wood furnace