Awesome service quick to respond! thanks! Our lines are open to our customers 24 hours a day, 7 days a week. The efficiency of a boiler is measured by its afue (annual fuel utilization efficiency) rating this rating is a measurement of how much heat a boiler produces vs how much fuel it consumes depending on the type of boiler you get, you may have the option to choose a boiler with an. Ed turned a nightmare into a relaxed leak free home thank.