Prescribed activities, s. 20.21 (1) of the Act
 2. (1) Subject to subsections (3) and (4), the following are prescribed activities for the purposes of subsection 20.21 (1) of the Act: 1. The use, operation, construction, alteration, extension or replacement of a heating system that meets the criteria set out in subsection (2) and that may discharge or from which may be discharged a contaminant into any part of the natural environment other than water. 2. The alteration of a process or rate of production with respect to a heating system that meets the criteria set out in subsection (2) if the alteration may result in, i. a contaminant being discharged into any part of the natural environment other than water, or ii. the rate or manner of discharge of a contaminant into any part of the natural environment other than water being altered. O. Reg. 346/12, s. 2 (1). (2) The criteria referred to in subsection (1) with respect to a heating system are the following: 1. The heating system uses only one or both of the following as fuel: i. Natural gas. ii. Propane. 2. The heating system includes one or more combustion units. 3. The thermal input rating of each combustion unit that is part of the heating system is not greater than 10.5 million kilojoules per hour. 4. The total thermal input rating of all of the combustion units in the heating system is greater than 1.58 million kilojoules per hour. 5. The wastewater from the heating system, if any, i. is transferred to a waste management system, A. that is subject to an environmental compliance approval, or B. in respect of which an activity has been registered for the purposes of subsection 20.21 (1) of the Act, ii. is discharged to a sewage works that is subject to an environmental compliance approval, or iii. is discharged to a municipal sanitary sewer. O. Reg. 346/12, s. 2 (2). (3) This section does not apply in respect of any activities relating to the construction of a heating system that are carried out at a site other than the building or structure at which the system is intended to be used. O. Reg. 346/12, s. 2 (3). (4) This section does not apply in respect of activities relating to the following heating systems: 1. A ground source heat pump as defined in Ontario Regulation 98/12 (Ground Source Heat Pumps) made under the Act. 2. A heating system that is, i. associated with a building or structure that contains one or more dwellings, and ii. used by the occupants of not more than three dwellings in the building or structure. 3. A heating system that is used in agriculture. 4. A heating system that also provides heat used in an industrial or manufacturing process. 5. A heating system that derives its heat from an industrial or manufacturing process. 6. A heating system that is used, at the site of a building or structure, for the construction, alteration, demolition, drilling or blasting of the building or structure. 7. A heating system that is used during an outdoor entertainment, artistic or sporting event, including an outdoor festival, fair, parade, fireworks display, art show, air show or car show, but not including a race of horses, dogs or motorized or non-motorized vehicles or boats. 8. A heating system that is used solely to mitigate the effects of an emergency declared to exist under the Emergency Management and Civil Protection Act. 9. A heating system that is part of a large municipal residential system or a small municipal residential system, as those systems are defined in Ontario Regulation 170/03 (Drinking Water Systems) made under the Safe Drinking Water Act, 2002. 10. A heating system that is used at a printing facility in respect of which an activity has been prescribed by Ontario Regulation 349/12 (Registrations Under Part II.2 of the Act — Printing) made under the Act. O. Reg. 346/12, s. 2 (4).