DOE Proposed Energy Standard Threatens Continued Manufacture of Cast Iron Boilers
The U.S. Department of Energy (DOE) is proposing a new Annual Fuel Utilization Efficiency (AFUE) standard for residential boilers that calls into question the continued viability of oil and gas fired cast iron boilers. The Energy Policy and Conservation Act authorizes DOE to regulate the energy efficiency of residential heating oil and gas boilers. Under EPCA, any new or amended energy conservation standard must achieve the maximum improvement in energy efficiency that is technologically feasible and economically justified. Under the proposal, cast iron hot water boilers fired by oil would be required to meet 88 AFUE, while similar hot water gas boilers would be assigned a 95 AFUE. If adopted, cast iron boilers will become more expensive, more complex with shorter life cycles and have higher service costs. In addition, cast iron boilers will become less efficient with a higher AFUE rating.
Achieving an 88 AFUE for oil-fired cast-iron boilers would be technically difficult according to manufacturers, requiring condensing heat exchangers that will add significantly to boiler cost, size and weight. Larger boilers increase jacket and idle loss resulting in higher annual energy consumption despite the increase in AFUE. Cast-iron boiler manufacturers are not sure they can reach an 88 AFUE without stack dampers which raise concerns about chimney temperatures and lack reliable sidewall vent options. Manufacturers contend they are already experiencing difficulty reaching 86 and 87 AFUE.
Moving gas boilers from 84 AFUE to 95 AFUE will likely eliminate gas cast iron boilers altogether according to manufacturers. Cast iron gas boilers have an approximate life span of 26 years while the alternative gas fired condensing boilers have a life span of only 10 years. Additionally, the water and flue passes in these boilers are too small to accommodate the proposed AFUE. Consequently, additional piping and filtering equipment is needed to keep them in service longer. The piping can cost $1000 to $1500 more to the consumer. Currently 2/3 of all cast iron boilers made are gas fired. The elimination of gas fired cast iron boilers will result in the closing of one of only two U.S. foundries resulting significantly higher costs for all boilers.
EMA will submit comments opposing the proposed oil and gas fired boiler AFUE and meet directly with the DOE to express the industry’s concern.