Oil fired boilers
An oil-fired boiler uses the same type of burner as an oil-fired, forced-air furnace, although a boiler is often somewhat smaller and heavier. There is no circulating fan and filter housing as with a forced-air system. Instead, most boilers require a circulating pump to push heat around the house through the pipes and the radiator system, as shown in Figure 5. The seasonal efficiency of old conventional hydronic systems is similar to that of conventional forced-air systems, which is around 60 percent.
A boiler’s energy efficiency performance over a heating season is called the Seasonal Energy Utilization Efficiency (SEUE). This SEUE is expressed as a percentage. For boilers with no standing pilot light, the SEUE is equivalent to the Annual Fuel Utilization Efficiency (AFUE). The higher the percentage, the more efficient the boiler. ENERGY STAR qualified oil-fired boilers must have an AFUE rating of 85 or higher.
