Connecting two LPG bottles together using a manifold might look straightforward — you're just joining a couple of fittings, right? Unfortunately, in New Zealand this work is legally classified as restricted gasfitting work, which means it must be carried out by a licensed gasfitter. Doing it yourself is not only illegal but could put your household at serious risk.
Why This Is Restricted Work
Under the regulations administered by the Plumbers, Gasfitters and Drainlayers Board (PGDB), any work that involves connecting, altering, or extending a gas installation — including LPG supply systems — is restricted gasfitting work. This applies whether the gas is natural gas or LPG (liquefied petroleum gas) in cylinders.
A twin-bottle manifold system is considered part of the gas installation because it directly controls the supply of gas to your appliances. Incorrectly fitted manifolds, regulators, or pigtail hoses can cause:
- Gas leaks, which can lead to fire or explosion
- Regulator failure, causing over-pressure to appliances
- Underpressure, meaning appliances don't burn correctly and can produce carbon monoxide
- Non-compliance with the NZ Building Code (particularly Clause G13 — Gas)
What a Twin-Bottle Manifold System Actually Involves
A twin-bottle (or dual-cylinder) manifold setup allows two LPG cylinders to supply gas simultaneously or automatically switch from an empty bottle to a full one. The system typically includes:
- Two LPG cylinders (commonly 9 kg or 45 kg)
- Pigtail hoses connecting each cylinder to the manifold
- An automatic changeover regulator or manifold block
- A single outlet running to your gas installation
Even though you can purchase manifold kits from suppliers, the act of connecting them to cylinders and your gas supply line is the restricted part. Purchasing the components is fine — installing them yourself is not.
What Homeowners Can and Cannot Do
| Task | Homeowner allowed? |
|---|---|
| Purchasing a manifold kit or regulator | ✅ Yes |
| Swapping out an empty LPG cylinder for a full one (same connection point) | ✅ Yes |
| Connecting pigtail hoses to cylinders and manifold | ❌ No — restricted work |
| Installing or altering the regulator or manifold | ❌ No — restricted work |
| Running new copper or flexible gas line from manifold | ❌ No — restricted work |
The one thing homeowners can do without a gasfitter is swap a single cylinder that uses a standard POL valve connection — this is considered routine cylinder exchange. But as soon as you're setting up a new manifold arrangement or altering the supply configuration, you need a licensed professional.
Regulations and Standards That Apply
LPG installations in New Zealand must comply with:
- NZ Building Code (gas installation requirements)
- NZS 5261 — the New Zealand standard for gas installation
- AS/NZS 1596 — storage and handling of LP gas
You can find more about the Building Code requirements at MBIE Building Performance. For the relevant standards, visit Standards NZ.
Note that a building consent is not usually required for like-for-like gas appliance connections, but any new gas installation work — including a new manifold setup — must still be done by a licensed gasfitter who issues a Certificate of Compliance (CoC) upon completion. Always confirm consent requirements with your local council.
Safety First: The Risks Are Real
LPG is heavier than air, meaning any leak will pool at ground level and in low-lying spaces — creating an invisible explosion hazard. Even a small leak from a poorly fitted pigtail hose or manifold fitting can accumulate quickly in an enclosed space such as a garage, laundry, or kitchen.
WorkSafe NZ has clear guidance on the dangers of LPG and the importance of correct installation. Never use thread tape (PTFE) or sealants on LPG fittings unless the manufacturer specifically states it is appropriate — LPG connections use compression or left-hand threaded fittings that seal differently from water plumbing.
If you ever smell gas: turn off the cylinder valve, ventilate the area, avoid switches or flames, and call your gas supplier or 111 if needed.
When to Call a Professional
You should engage a licensed gasfitter for any of the following:
- Setting up a new twin-bottle or multi-cylinder manifold system
- Upgrading from a single cylinder to a dual-cylinder supply
- Replacing or relocating a regulator
- Any new gas pipework from the manifold to appliances
- Annual or periodic inspection of your LPG installation
A licensed gasfitter will ensure the work meets NZS 5261, issue you a Certificate of Compliance, and give you peace of mind that your system is safe. You can find qualified, local gasfitters on tradedirectory.co.nz.
To verify a gasfitter's licence before hiring, check the Plumbers, Gasfitters and Drainlayers Board register — it's free and takes only a minute.
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