In accordance with the standards and criteria in § 261.10 (definition of "boiler") and the procedures in § 260.33, the Secretary may determine on a case-by-case basis that certain enclosed devices using controlled flame combustion are boilers, even though they do not otherwise meet the definition of boiler contained in § 260.10, after considering the following criteria:
(a) The extent to which the unit has provisions for recovering and exporting thermal energy in the form of steam, heated fluids, or heated gases;(b) The extent to which the combustion chamber and energy recovery equipment are of integral design;(c) The efficiency of energy recovery, calculated in terms of the recovered energy compared with the thermal value of the fuel;(d) The extent to which exported energy is utilized;(e) The extent to which the device is in common and customary use as a "boiler" functioning primarily to produce steam, heated fluids, or heated gases; and(f) Other factors, as appropriate. (Amended November 21, 1985, July 23, 1996)
7 Del. Admin. Code § 1302-260-C-260.32