Direct heating equipment are small heaters that are located in the space to be heated and can be either permanently installed or portable. Common names for this equipment include space heaters, wall heaters, floor heaters, and room heaters. They are predominantly fired with natural gas or propane — some require electricity for certain operations like fan motors or electrical vent dampers — and only these units are covered by federal standards.
On April 16, 2010, DOE issued a final rule for amended standards for residential direct heating equipment. The standards depend on unit type and input capacity, with the AFUE ranging from 57% for a small floor unit to 76% for a large, fan-assisted wall unit. The standards will become effective April 16, 2013. According to DOE, the standards will save .2 quads of energy over 30 years, consumers will save about $500 million and carbon dioxide emissions will be cut by about 9 million metric tons.
In October 2015, DOE initiated a rulemaking to develop updated standards for direct heating equipment.
Baseline direct heating units generally consume 200–300 therms annually, depending on the type of unit. Based on the maximum technologically-feasible efficiency levels identified by DOE, there is potential to further reduce energy use by up to 28% depending on the specific product. Manufacturers improve the AFUE of direct heating equipment primarily through improvements in the heat exchanger design, though the DOE has identified a dozen other technology options that can also improve efficiency. These improvements include, but are not limited to: electronic ignition (part of the proposed standard), improved fan or blower motor efficiency, thermal or electric vent damper, and induced draft.