There is a cost (called standby loss) associated with boilers during the off cycles. Reducing standby loss means increasing fuel efficiency. The low-mass concept virtually eliminates standby loss, providing nearly instant heating with less fuel combustion. Thermo-Dynamics has combined this low-mass concept with the ultra-modern technology of high-efficiency, flame, retention burners that produce a cleaner, more efficient flame. This system ensures maximum efficiency from every fuel dollar.