Short answer: gas is a proven off-grid choice, electric is simple when 240V mains is available, and diesel can consolidate fuel for diesel-based touring or combine space and water heating. Gas/electric and other combination units provide flexibility but add cost, controls and installation considerations.
Comparison
| System | Strength | Main limitation | Typical fit |
|---|---|---|---|
| Gas storage or instantaneous | Off-grid heat without a large inverter load | LPG supply, ventilation and gas installation | Mixed caravan-park and off-grid touring |
| 240V electric storage | Quiet and simple on a powered site | Large continuous load; impractical for many battery systems | Frequent powered-site use |
| Diesel combination | One fuel can provide space heat and hot water | Complex installation, electrical start-up and servicing | Cold-climate or diesel-based touring |
| Gas/electric hybrid | Choose fuel or mains and sometimes combine modes | Higher purchase and installation complexity | Travellers wanting maximum flexibility |
Storage, instantaneous and combination units
A storage heater warms a finite tank—commonly around 10 to 14 litres in caravan products—then reheats it after use. Mixing hot with cold water increases the shower volume. An instantaneous unit heats water as it flows and needs sufficient fuel, water flow and temperature rise. A combination appliance heats the living space and water in one housing.
Compare usable shower performance, not just tank capacity. Incoming water temperature, flow rate, thermostat setpoint and plumbing length all affect the result.
Electric does not automatically mean battery-friendly
Electric water-heater elements are often a substantial 240V load. They work well on a powered site, but heating several litres of water from cold requires significant energy. If you plan battery operation, include inverter losses and other appliances rather than considering the heater alone.
Off-grid fuel choices
Gas systems can heat water without a large electrical element, although ignition and controls may still use 12V. Diesel combination heaters also need reliable 12V supply through start-up and cool-down. Record actual fuel consumption and electrical demand from the exact manual.
Water conservation beats a bigger heater
Hot-water comfort is limited by fresh-water capacity and grey-water storage as much as heating. Use a low-flow shower head, wet down, switch off while soaping, then rinse. Estimate the whole trip with the Water Autonomy Planner and water-weight calculator.
Safety and maintenance
Any combustion appliance needs the approved flue, combustion air and clearances. Gas and 240V work must be completed by appropriately licensed people. Follow the manual for draining in freezing conditions, pressure limits, anode replacement where fitted, descaling and sanitising. Never cap a pressure-relief outlet or operate a storage heater empty unless its manual explicitly allows it.
Decision guide
- Mostly powered sites: electric can be simple and avoids using LPG for water.
- Regular off-grid touring: gas or a fuel-fired combination unit is usually more practical.
- Cold-climate travel: a combination space/water heater may save installation space.
- Families: prioritise recovery time, water capacity and a realistic shower routine.
Before buying, verify dimensions, wet and dry weight, service access, pressure compatibility, current draw, fuel consumption and Australian support.
An Australian touring scenario
Two adults who mainly use powered caravan parks may be satisfied with an electric storage heater and the site amenities as backup. A family free-camping for several nights may need gas recovery and strict water rationing. A winter tourer installing space heating may save room with a diesel or gas combination appliance. The largest heater is not automatically best: extra hot-water capacity also encourages water use and adds carried mass.
Limits of brochure comparisons
Published heat-up times depend on starting temperature, target temperature, mode and water volume. Instantaneous systems depend on flow rate and temperature rise, while storage systems depend on mixed-water use and recovery. Compare specifications under the same assumptions. Also distinguish the thermal power delivered to water from the electrical current needed for controls or heating elements.
What to verify before buying or changing the system
- Storage capacity or rated flow at the expected temperature rise
- Heat-up and recovery time in every intended energy mode
- 240V element demand and campsite circuit limits
- Gas or diesel consumption plus 12V control current
- Dry weight, filled weight and effect on axle loading
- Pressure limits, pump compatibility and frost-protection method
- Flue, drain and service-access locations
- Australian warranty, parts and licensed service support
Ongoing operation and maintenance
Drain or protect the system before freezing conditions as the manual requires. Flush sediment, descale and sanitise at the stated intervals, using products compatible with tank materials. Inspect pressure-relief discharge and never block it. Before switching on, confirm a storage heater is filled if the manual requires water. A change in smell, colour, heating time or relief-valve behaviour warrants inspection.
A fair way to compare quotes
Give every supplier the same written brief: travelling party, normal destinations, longest unserviced stay, existing equipment, available installation space and remaining payload. Ask for the exact model numbers and manuals rather than accepting a category description. The quote should separate hardware, installation, commissioning, certification where applicable and removal or safe decommissioning of old equipment. It should also state exclusions, warranty responsibility and the added installed mass.
Compare the proposals against the same ordinary worst case. For electrical systems, that may be consecutive cloudy days and the largest simultaneous load. For water or waste systems, it may be the longest stay before lawful refill or disposal. For fuel-burning equipment, include cold starts, ventilation, fuel availability and servicing. A design that works only under ideal sun, perfect coverage or unlimited site facilities is not a touring plan.
Score each option for five things: safety and compliance, fit with your actual travel, payload, daily effort and recoverability after a fault. Purchase price belongs in the comparison, but so do new chargers, tanks, vents, cabling, plumbing, certification and future consumables. Give extra weight to factors that can strand you or close access to a campsite.
Plan for a fault, not just normal operation
Ask what happens when the chosen system fails on a Sunday in a regional town. Identify the safe isolation method, what other equipment is affected, whether the caravan remains usable and which parts are realistically stocked in Australia. A highly integrated appliance can save space but may remove several functions at once. Separate systems can provide redundancy but add weight, connections and maintenance. There is no universal winner; record the consequence that matters to your trip.
Carry only the spares and tools the manufacturer permits an owner to use. Do not bypass fuses, pressure devices, ventilation, battery management or combustion safety controls to keep travelling. If a fault involves gas, 230V electricity, overheating, fumes, damaged lithium batteries or leaking waste, isolate the equipment if safe, move people away from the hazard and obtain qualified assistance.
Recheck the decision when your travel changes
A setup chosen for powered coastal parks may not suit a remote inland season. Revisit capacity, fuel, payload and service access after adding appliances, changing tow vehicles, travelling with more people or planning longer stays. Reweigh after material modifications and keep the measured axle and total masses with the system records. This prevents several individually reasonable upgrades from quietly consuming the safety margin.
When keeping the current system is sensible
An upgrade is not automatically progress. If the present equipment is safe, supported and reliably covers your ordinary trips, maintenance or a small complementary item may solve the real problem with less weight and complexity. Replace equipment when measured performance, route requirements, safety, serviceability or a clearly defined new use justifies the change—not simply because a newer technology is popular.
Commissioning and trip records
Before departure, ask the installer to demonstrate normal operation, isolation, alarms, fault messages and safe shutdown. Keep the manual, model and serial number, invoice, commissioning information and a simple diagram with the caravan records. On the first trip, note energy or fuel use, temperatures, refill or disposal intervals and any nuisance alarms. Those observations turn the next adjustment into evidence-based maintenance rather than guesswork.
Your practical next step
Measure one real shower and a normal dishwashing session. Calculate both fresh water used and grey water created, then compare that with tank capacity and disposal intervals. Select the energy source only after the water routine is credible; heating water you cannot carry or retain is not useful autonomy.
Sources and further reading
- Truma Australia water systems
- Truma guide to caravan and motorhome water heaters
- Truma Australia current manuals and downloads
Information checked 24 August 2026. Product specifications and campsite rules can change; confirm the current manual and local requirements before relying on them.
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