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Efficient boiler settings
If this is wired to be cold start then whenever the burner runs you should be able to look at the lights on the right side of the taco relay and see why the burner is running. 100 gallons in 6 weeks does not seem excessive ,see how many degree days elapsed in that period for your area in Maine. It's only 2 or 3 gallons a day.Is the house well insulated, including the basement ceiling?