We recommend you discuss your plan to install a second-hand woodburner with your local city or district council or the unitary authority in your area before purchasing the woodburner. There are factors in addition to the National Environmental Standards for Air Quality that these agencies need to consider before permitting the installation of a second-hand woodburner.
See more information at https://environment.govt.nz/acts-and-regulations/regulations/national-environmental-standards-for-air-quality/