If an efficient oil boiler consumes an average of 10 gallons weekly in a 'shoulder' period like late October (10 year old well insulated modern house with Anderson Windows), how much more will it consume during the peak heating months of Dec/Jan/Feb. 50% more? 100% more? The house seems to retain heat quite effectively - after 9PM when the timer turns the thermostat down to 62º, the house is still at 70º at 9PM. On a 27º night recently, the house only dropped to 66º by 5AM after 8 hours with zero heat from that zone. So I'm thinking that in January we'll need more oil to heat the place, but not twice as much.
Any thoughts on this?