In all cases where the use of recirculated air is permitted, the required outdoor air supply may be reduced up to fifty per cent, provided that the recirculated air is passed through adsorption devices. The adsorption devices shall be approved and rated. Means shall be provided for maintaining the effectiveness of the adsorption devices.
(a) Improper maintenance. Should the adsorption devices be improperly maintained so that their effectiveness is impaired, the commissioner may order their removal. If the adsorption devices are removed, the air conditioning or ventilating system shall not be operated without supplying one hundred per cent of the outdoor air required by this article or article eight of this subchapter.
(b) Test records. The building owner shall, at all times, maintain a maintenance record showing the manufacturer's recommendation of the frequency of tests, the method of making tests, and the results of all tests of the adsorption devices. Such tests shall be made and certified by the manufacturer or by a laboratory acceptable to the commissioner at least twice every six months. The records of such tests shall be maintained for a period of at least two years, and shall be available for inspection by the commissioner.
(c) Ventilation of water closet compartments. The use of any device that returns exhaust air from water closet compartments or from toilet rooms after passing through adsorption devices is not permitted as a means of providing ventilation for a water closet compartment for which a mechanical system of ventilation is required.