If you've ever moved house and wondered whether your gas hob will work with the new property's gas supply, you're not alone. Natural gas and LPG (liquefied petroleum gas) are both common fuel sources in New Zealand homes, but they are chemically different gases that burn at different pressures — and appliances are specifically designed for one or the other. Using the wrong gas type can be dangerous and is a breach of the NZ Gas Regulations.
What Is Natural Gas?
Natural gas is primarily methane. In New Zealand it is supplied through a reticulated (piped) network, mainly in the North Island — particularly in cities like Auckland, Hamilton, Wellington, and Palmerston North. It arrives at your home at a relatively low pressure through underground pipes managed by network operators. Because it is lighter than air, natural gas tends to rise and disperse if there is a leak, which influences how appliances and ventilation are designed.
What Is LPG?
LPG (liquefied petroleum gas) is a mixture of propane and butane, stored under pressure as a liquid in cylinders or larger tanks. It is available nationwide, making it the go-to option in rural areas and the South Island where reticulated natural gas is not available. LPG is heavier than air, so a leak will pool at floor level — an important safety consideration. LPG is supplied by companies such as Rockgas, Elgas, and Supergas, typically in 9 kg swap-and-go cylinders or larger 45 kg cylinders for homes with higher demand.
Key Technical Differences
The differences between the two gases go beyond just the cylinder versus pipe delivery. The table below summarises the main technical distinctions:
| Feature | Natural Gas | LPG |
|---|---|---|
| Main component | Methane | Propane / Butane |
| Supply method | Reticulated (piped) | Cylinders or bulk tank |
| Supply pressure (approx.) | Low (around 1.1–2.75 kPa) | Higher (around 2.75 kPa regulated) |
| Density vs air | Lighter — rises | Heavier — sinks |
| Burner jet size | Larger orifice | Smaller orifice |
| Availability in NZ | Mainly North Island cities | Nationwide |
Because LPG has a higher energy content per cubic metre than natural gas, appliances need different burner jets (orifices) to control the flame correctly. A natural gas appliance run on LPG will produce an oversized, dangerous flame. An LPG appliance run on natural gas will likely produce a weak, inefficient flame or may not function at all.
Can You Convert an Appliance from One Gas to Another?
Many modern gas appliances — hobs, ovens, heaters, and hot water systems — can be converted between natural gas and LPG, but this is not a DIY job. Conversion involves changing the burner jets, adjusting the gas pressure regulator, and sometimes modifying the air-to-gas ratio settings. Under the NZ Gas (Safety and Measurement) Regulations, this work must be carried out by a licensed gasfitter registered with the Plumbers, Gasfitters and Drainlayers Board (PGDB). Attempting a conversion yourself is illegal and could void your home insurance.
Always check whether your appliance has a conversion kit available from the manufacturer before purchasing. Some cheaper imported appliances may not have approved conversion kits for the NZ market.
Buying a New Appliance: What to Check
When shopping for a new gas appliance, always confirm:
- Which gas type it is set up for — the label or manual will state "NG" (natural gas) or "LPG"
- Whether a conversion kit is included or available
- That the appliance carries a New Zealand approval mark (look for the NZ Gas Association approval or equivalent)
- The MJ/hr (megajoule per hour) rating matches your intended use
Retailers such as Bunnings and Mitre 10 stock appliances for both gas types, and staff can usually advise on conversion options.
Ventilation and Installation Requirements
Both gas types require adequate ventilation, but the requirements differ due to the density difference. Because LPG sinks, any LPG installation must ensure there are no low-lying enclosed spaces (like under-floor cavities) where gas could accumulate. The NZ Building Code clause G12 covers gas installations, and all fixed gas appliance installations must comply with the relevant NZ standards. BRANZ provides useful guidance on ventilation requirements for gas appliances in NZ homes.
Running Costs: Natural Gas vs LPG
As a general guide, natural gas tends to be cheaper per unit of energy than LPG in areas where it is available, because reticulated supply is more efficient than cylinder delivery. However, LPG offers flexibility and is often the only practical option outside main urban centres. Your actual running costs will depend on your usage, the efficiency rating of your appliances, and current supplier pricing — it pays to get quotes from multiple LPG suppliers if you are on cylinders.
When to Call a Professional
Gas work in New Zealand is restricted work under the Gas Act 1992 and associated regulations. You must use a licensed gasfitter for:
- Installing, replacing, or relocating any gas appliance
- Converting an appliance between natural gas and LPG
- Connecting or disconnecting gas lines and fittings
- Commissioning a new gas system or appliance
- Any work on gas pipework inside or outside your home
As a homeowner, you may be able to swap an LPG cylinder on an existing, already-connected regulator and hose — but always check with your supplier and ensure hoses and fittings are in good condition and within their service life.
Safety note: If you ever smell gas, do not operate any switches or appliances. Ventilate the area immediately, leave the building, and call your gas supplier's emergency line or 111. Never attempt to locate a gas leak yourself with a flame.
You can find a qualified, licensed gasfitter in your area through tradedirectory.co.nz — always ask to see their PGDB licence before work begins.