Check out www.hotwatercylinder.co.nz they will help you!

No problem! The first thing to take into consideration is the type of gas.  LPG or NG? Most providers take to long and charge to much to supply a meter. Then there is the cost of your gas fitter.. A LPG twin bottle setup can be arranged much quicker and cheaper, Gasfitter cost would be around the same though (also has disadvantages). Everything depends on your type of property, If you are installing it externally or internally (flue to go through he roof etc..) and if (NG) Gas is available. I would recommend doing the numbers before you decide to go with gas, find out how much you will be consuming to compare it with an electrical HWC. If you are looking at saving on you energy bill I would recommend looking at www.solarheating.co.nz they are offering a solar electricity deal. They simply retrofit solar panels into your existing Hot water cylinder and you will start saving immediately. You can pay for the complete installation through your power bill. Hope this helps.