Did a quick google search for you, as per "http://www.gasmate.co.nz/faqs.php#show":
Q: I have Natural Gas in my house and I wish to connect my barbecue to an existing outside mains gas connection. Can I convert my LPG barbecue to Natural gas?
A: It is possible to convert a barbecue to natural gas. Any conversions will need to be carried out by a craftsman gas fitter at the owners expense. The gas fitter will need to certify that the appliance is compliant with the current version of NZS 5261.
Validity of warranty claims will be subject to proof of purchase of an approved conversion kit as well as for the BBQ. Approved conversion kits are available through your local plumbing merchant. The conversion kit part number is as follows, NGC001. this kit may not fit all models of BBQ.作者: 117wik 时间: 2013-9-8 15:01:16
i think you need to buy something similar to "http://www.trademe.co.nz/home-living/outdoor-garden-conservatory/bbqs-outdoor-ovens/4-burners-or-more/auction-630957882.htm". you should probably get a proper plumber/certified trades person to do this though.