"Auxiliary boiler" means, for purposes of Part 217, a boiler that is operated only when the main boiler or boilers at a source are not in service and is used either to maintain building heat or to assist in the startup of the main boiler or boilers. This term does not include emergency or standby units and load shaving units.
Ill. Admin. Code tit. 35, § 211.665
Added at 33 Ill. Reg. 13326, effective August 31, 2009