Persons licensed by the Liquefied Petroleum Gas Board pursuant to the Liquefied Petroleum Gas Board Act, § 15-75-101 et seq., are exempt from the provisions of this chapter pertaining to heating, ventilation, air conditioning, and refrigeration when:
(1) Engaged in the installation, repair, or replacement of a liquefied petroleum gas appliance so long as the appliance is not connected to a refrigeration system, except that such persons may also engage in the replacement or repair of a liquefied petroleum gas central heating unit when it is combined with an air conditioning unit; and
(2) Engaged in the installation of a venting system required for a vented-type liquefied petroleum gas appliance.