Gas storage, and how it differs from a califont
Rheem describes a gas storage heater as one that heats the water and stores it ready for use, supplying it at mains pressure. The other kind, gas continuous flow, heats water only when a hot tap is open. That's the one often called a califont.
Where there's no piped natural gas, Rheem says an LPG model can run from refillable gas bottles. Not every model suits both: Rheem's outdoor Stellar gas storage heater is natural gas only, for example.
Rheem also says most gas storage heaters can be connected to the gas pipe a house already has, while a continuous flow unit needs a larger pipe from the meter. Your gasfitter checks what your house has. For other cylinder types, see our hot water cylinders guide.
Who is allowed to do it
All gasfitting is restricted work, and only a person authorised under the Plumbers, Gasfitters, and Drainlayers Act 2006 may do it. A licensed gasfitter whom the PGDB accepts as competent may also fit the gas water heater and the water pipes to and from it, in the circumstances a licensed plumber could. Restricted gasfitters can't connect an appliance to the gas supply.
The penalties are steep: unauthorised gasfitting carries fines of up to $50,000 for an individual and $250,000 for a company. In October 2026 the PGDB reported a repeat offender fined $14,000 for unauthorised gasfitting and plumbing, including installing a gas water heater at a home and handing over a Gas Safety Certificate he had no authority to issue.
Gas paperwork for a water heater
| When it applies | What to expect | |
|---|---|---|
| Gas Safety Certificate | All gasfitting, once it's finished and connected | Issued by whoever connects it (or their supervisor) if satisfied it's safe. PGDB says you should have a signed certificate within 20 working days of connection. |
| Gas certificate of compliance | General and high-risk gasfitting. A brand-new installation is general | The work doesn't count as complete until it's issued |
| Like-for-like swap | An equivalent appliance with no change to pipework, flue, pressure, gas type, ventilation or energy use | Low-risk gasfitting: a certificate of compliance is optional, the Gas Safety Certificate isn't |
Keep those certificates
Gas certificates may be wanted when you sell the house or make an insurance claim, and a gas supplier may ask for one before supplying gas or refilling LPG bottles. If one goes missing, another certifying gasfitter can check the installation and issue a certificate of verification.
Under the Building Act, the same paperwork is called an Energy Works Certificate, so don't be thrown if you see both names.
Signs to ring a gasfitter
- The burner won't light, or keeps going out.
- No hot water while your other gas appliances work.
- Soot or scorch marks around the heater or flue.
- Water pooling around the base.
- The heater is old and you're weighing up storage against continuous flow.
If you smell gas
Don't light anything or use switches. If it's safe, turn the gas off at the meter or bottle, get everyone outside, and ring 111 if anyone is in danger. Our gas leaks page has the full steps.
Yours, and the gasfitter's
You can
- Check the gas is on at the meter or the bottle.
- Keep the flue and the space around the heater clear.
- Store your gas certificates with the house papers.
Leave to an authorised tradie
- Any work on the burner, controls, gas pipes or flue.
- Connecting or disconnecting the heater.
- Checking ventilation and commissioning.
- Issuing the gas certificates.
Questions for the gasfitter
- Are you a certifying gasfitter, or who supervises you?
- Is this low-risk, general or high-risk gasfitting?
- Which gas certificates will I get, and when?
- Can our existing gas pipe supply this heater?
- Does this model run on natural gas, LPG or both?
What we would do
Treat a gas cylinder as two jobs in one, water and gas. Make sure the person doing it holds a current gasfitting licence, look them up on the PGDB register, and don't settle the bill until you know which certificates are coming. A gas water heater specialist will expect those questions.