Thermal transfer is proportional to the difference in temperature between the inside and outside of your house. For every bit of energy you put into maintaining

Thermal transfer is proportional to the difference in temperature between the inside and outside of your house. For every bit of energy you put into maintaining the difference some energy is lost to the atmosphere. If your system is equipped with an aquastat that turns the circulator pump on only after the water reaches a certain temperature then it is possible to waste energy if the boiler runs for a short time and the water does not warm up enough to start the circulator.