Switching from LPG (liquefied petroleum gas) to natural gas (reticulated or piped gas) is a significant change that affects every gas appliance in your home. The two fuels burn at different pressures and have different energy content, so you can't simply connect your existing appliances to the new supply without making adjustments. In most cases, appliances need to be converted or replaced, and all of this work must be carried out by a licensed gasfitter.
Why LPG and Natural Gas Are Not Interchangeable
LPG and natural gas are chemically different fuels. LPG (typically propane or butane) burns at a higher pressure and has a higher calorific value (energy per cubic metre) than natural gas (predominantly methane). Because of these differences:
- Burner jets (orifices) are sized differently for each fuel — an LPG jet is smaller to restrict flow, while a natural gas jet is larger.
- Gas pressure regulators are set to different operating pressures.
- Air-to-fuel ratios differ, affecting combustion quality and safety.
Running an LPG-configured appliance on natural gas (or vice versa) can result in incomplete combustion, sooty flames, carbon monoxide production, or even a dangerous gas leak. This is why conversion is not a DIY job.
Which Appliances Are Affected?
Every gas appliance in your home is affected when you switch fuel types. Common appliances include:
- Cooktops and ovens — burner jets and pressure regulators must be changed.
- Hot water heaters (continuous flow or storage) — jets, regulators, and sometimes burner assemblies need conversion.
- Space heaters and flued heaters — require jet and regulator changes; some older models cannot be converted.
- Gas fireplaces — conversion kits are available for many models, but not all.
- Barbecues and outdoor heaters — these are often not connected to the fixed supply, but any that are must be converted.
Can All Appliances Be Converted?
Not always. Many modern appliances come with a conversion kit supplied by the manufacturer, and your gasfitter can fit this during the switchover. However, older or cheaper appliances may not have conversion kits available, or the cost of conversion may make replacement more economical. Your licensed gasfitter can advise you on a case-by-case basis.
The Conversion Process
A typical LPG-to-natural-gas conversion involves:
- Disconnecting the LPG supply — your LPG cylinder or tank is removed by your supplier.
- Connecting to the natural gas network — this requires a new meter and pipework from the street, installed by your gas network operator (e.g., Vector, First Gas) and a licensed gasfitter.
- Converting each appliance — your gasfitter replaces jets, adjusts or replaces regulators, and checks burner performance on every appliance.
- Testing and certification — all work must be tested for gas tightness and correct operation. Your gasfitter issues a Certificate of Compliance for the work.
This is restricted work under the Gas Act 1992 and must be performed by a gasfitter licensed by the Plumbers, Gasfitters and Drainlayers Board (PGDB). It is illegal for an unlicensed person to carry out gas fitting work in New Zealand.
Building Consent Considerations
Connecting to a new reticulated natural gas supply typically involves work to the fixed gas installation, which may require a building consent depending on the scope. Always check with your local council before work begins. The MBIE Building Performance website has guidance on what work requires consent and what may be exempt under Schedule 1 of the Building Act 2004 — but confirm with your council, as interpretations can vary.
Cost Considerations
As a rough guide, the cost of converting appliances varies depending on the number and type of appliances, the complexity of the pipework, and your location. Conversion kits for individual appliances can range from a modest sum to several hundred dollars each, plus the gasfitter's labour. In some cases, replacing an older appliance outright may be more cost-effective than converting it. Get quotes from a qualified gasfitter before committing.
It's also worth considering the ongoing running costs of natural gas versus LPG in your area. Natural gas is only available in certain parts of New Zealand (mainly larger urban centres), so check with your local network operator whether reticulated gas is available at your address. The Energywise website has useful information on comparing home energy options.
Safety Note
Never attempt to modify gas jets, regulators, or pipework yourself. Carbon monoxide is odourless and can be fatal. If you ever smell gas, turn off the supply at the meter, ventilate the area, and call your gas supplier or 111 — do not operate any switches or flames. WorkSafe NZ provides guidance on gas safety in the home.
When to Call a Professional
All gas conversion work — from the meter connection through to appliance conversion and testing — is legally restricted work in New Zealand. You must use a licensed gasfitter for every part of this process. Always ask to see their PGDB licence before work begins, and ensure you receive a Certificate of Compliance on completion.
You can find qualified, local gasfitters in your area right here on tradedirectory.co.nz.
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