The owner or user of a boiler required by this chapter to be inspected by the Commissioner of Administrative Services, state boiler inspectors or special inspectors shall pay to the commissioner the sum of eighty dollars for each operating certificate issued. No fee shall be required of the state or any agency of the state. All fees collected by the commissioner under authority of this chapter shall be transferred by the commissioner to the State Treasurer for deposit in the General Fund. If the report of inspection by the Department of Administrative Services inspector or special inspector indicates that any boiler meets the requirements of this chapter and the boiler regulations, an operating certificate shall be issued by the commissioner to the owner or user. Such certificate shall state the pressure and other conditions under which such boiler may be lawfully operated. An operating certificate shall be valid for a period of not more than twelve months from the date of internal inspection, in the case of power boilers inspected pursuant to subdivision (1) of § 29-237, except that the certificate shall be valid for a period of not more than two months beyond the period set by the Commissioner of Administrative Services in accordance with § 29-237. An operating certificate shall be valid for a period of not more than eighteen months from the date of internal inspection in the case of power boilers inspected pursuant to subdivision (2) of § 29-237. Operating certificates shall be valid for twenty-four months in the case of low pressure steam or vapor heating boilers, hot water heating boilers, hot water supply boilers and hot water heaters approved by a nationally recognized testing agency. If a boiler inspected by a state boiler inspector or special inspector commissioned by said commissioner is found to conform with the requirements of this chapter and the boiler regulations, an operating certificate shall be issued by said commissioner to the owner or user upon the receipt of the insuring company’s report or the state boiler inspector’s report. Said commissioner may order reinspection if reasonable doubt exists regarding any inspection. Such certificate shall state the pressure and other conditions under which such boiler may be lawfully operated and shall be valid not more than the period indicated in this section and shall be renewed each year in the case of power boilers inspected pursuant to subdivision (1) of § 29-237, every eighteen months in the case of power boilers inspected pursuant to subdivision (2) of § 29-237, and biennially in the case of hot water heating or hot water supply boilers and hot water heaters. An operating certificate shall be immediately invalid if the boiler is relocated or altered, unless such relocation or alteration has been approved in accordance with this chapter or the boiler code and regulations. No boiler shall be operated unless a valid operating certificate is displayed under glass in a conspicuous place in the room in which such boiler is located. If the boiler is not located within the building, the certificate shall be posted in a location convenient to the boiler inspected. In the case of a portable boiler such certificate shall be kept in a metal container to be fastened to the boiler or kept in a tool box accompanying the boiler.