Gas & continuous flow
Gas Hot Water & Califont Systems
Califont is the term most New Zealanders use for a gas water heater — a continuous-flow (instantaneous) unit that heats water on demand rather than storing it. Whether you run natural gas or LPG, califonts eventually reach the point where repair, replacement or a change of system needs to be considered.
At a glance
Gas Hot Water & Califonts — key points
- Califont replacement and upgrades
- Continuous-flow gas water heating
- Natural gas and LPG systems
- Ignition, flow and temperature faults
- Ageing or unsupported models
- Electric and heat pump alternatives
How continuous-flow gas hot water works
A continuous-flow califont heats water only when a hot tap is opened. Water passes through a heat exchanger, a gas burner fires, and heated water is delivered on demand — which is why there is no cylinder and, in principle, no running out of hot water.
Performance is limited by flow rate rather than stored volume. Running several outlets at once can exceed the unit's capacity, resulting in temperature drops.
Common califont problems
Gas hot-water faults often show up as inconsistent temperature, failure to ignite, error codes on the controller, reduced flow or water that never reaches the set temperature.
Some faults are straightforward service items; others indicate that an ageing unit is approaching the end of its usable life. Gas appliance work must be carried out by a suitably qualified gasfitter.
- No hot water or the unit will not fire
- Temperature fluctuating during a shower
- Error codes on the controller
- Reduced hot-water flow rate
- Unit short-cycling or making unusual noises
- Ageing unit with limited parts availability
Replacement and alternatives
When a califont is beyond economic repair, options include replacing it with a modern continuous-flow unit, or moving to an electric solution such as a mains-pressure cylinder or heat pump hot water system.
For homes on bottled LPG in particular, ongoing gas supply costs are often part of the decision. A professional assessment will consider your property, existing pipework, electrical capacity and household demand.
Questions
Frequently asked questions
What is a califont?
In New Zealand, califont is the common term for a gas water heater that heats water instantaneously as it flows through the unit — also known as a continuous-flow or instantaneous gas water heater.
How long does a gas califont last?
Service life varies with model, water quality, servicing and installation, but many units are replaced after roughly 10 to 20 years. Parts availability for older models can influence the repair-or-replace decision.
Should I replace gas with electric?
It depends on your property, energy costs, available space and how much hot water your household uses. There is no universal answer — a qualified professional should assess your situation before you commit to a change of system.
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