Caravan hot water systems: types, anodes, valves and 240V faults
A caravan hot water system stores water in a tank or heats it as it flows.
Tanks and instant units need different care.
Published . 10 min read • Technical Guide
- The tanks in this guide hold 10 to 28 litres. The instant units run on gas with 12V power.
- If your heater's manual names an anode, follow its check times.
- On 240V, check site power, the safety switch and a full heater tank. Gas and 240V repairs are for licensed trades.
Find out which hot water system your van has
Look on the heater's outside door or label, or in your van's paperwork. This guide covers three kinds.
Storage tanks
A storage tank heats a set amount of water and keeps it hot. These tanks run on gas, on 240V, or on both.
- •Suburban SW4 and SW6: 15.1 and 20.3 litres. Models with an electric element use 1440 watts (W) on 240V.
- •Swift, the 28-litre model in its manual: gas, electric and dual versions, with a 1 kilowatt element. On electric it is usable in about 40 minutes and full temperature in 1 hour.
- •Truma UltraRapid: 14 litres, gas or gas and electric. Truma lists 1415 W on 240V. From 20 to 65 degrees takes 45 minutes on gas, 40 on electric and 28 on both.
Instant units
An instant unit heats water as it flows, so it has no hot tank to wait for. These units run on gas with 12V power, and each needs a minimum flow at the tap before it starts.
- •Suburban ST-60: needs more than 0.7 gallons a minute, about 2.6 litres.
- •Truma AquaGo comfort: starts above about 1.5 litres a minute. The standard setting is 49 degrees.
- •Camec 13kW: needs 1.5 litres a minute. It sets from 35 to 60 degrees and gives 5 litres a minute at 37 degrees.
Combined heaters
A combined heater warms the van and the water from one unit. Truma's Combi 2E and 4E hold 10 litres. Truma lists about 23 minutes to heat the water from 15 to 60 degrees, or about 90 minutes with the van heater running as well.
Hot water not working on 240V: first checks
Check the van is plugged in and the heater's tank is full before 240V goes on. The heater's tank is full when water runs from a hot tap. Then follow the list for your heater. Each list is that maker's own.
Suburban SW with an element
- •Check the heater's tank is full. Suburban says the most common trouble comes from switching on before the tank is filled.
- •Turn off the gas supply to the heater, then turn the circuit breaker to on.
Truma UltraRapid
- •Connect the van to the site supply.
- •Check the safety switch, which Truma calls the residual current circuit breaker.
Swift
- •Check the heater's tank is full and water flows from a hot tap.
- •Turn on the switch at the power point.
- •Allow time. Swift says the water reaches a usable temperature in about 40 minutes.
Stop and call a licensed tradesperson if:
- •These checks do not bring the hot water back. The thermal cut-out may have tripped.
- •The thermal cut-out on the 240V side has tripped. Suburban, Truma and Swift each say this shows a possibly dangerous situation, and not to reset it until a qualified person has serviced the heater.
- •You find the tank empty with the power on. Turn the power off and have the element checked before you use 240V again.
- •The safety switch trips again after you reset it.
Suburban says all electrical work is for a licensed electrician.
The instant units in this guide run on gas with 12V power. For those, and for any heater that will not light on gas, start with our hot water fault checks.
Check your heater's anode if it has one
An anode is a metal rod inside some water heaters. It corrodes in place of the tank, which helps the tank last longer. Check your heater's manual for one.
Suburban SW tanks
- •The anode is magnesium or aluminium.
- •Check it every 6 months. Let the tank cool and drain it first, using the steps under servicing. Replace the anode when it is below 50% of its original diameter.
- •Suburban says running the tank without its anode voids the inner tank warranty. Skipping the 6-monthly check also voids that warranty.
- •Suburban says to use only genuine Suburban rods, and that other rods may void the warranty. The rod itself is not covered by warranty.
- •The rod is 215 millimetres (mm) long and 17 mm across. Use a thread sealant approved for drinking water.
Other heaters
- •Swift says its stainless tank does not need an anode to prevent corrosion. Its anode tube protects against bacteria if untreated bore water gets in, and only needs replacing after long periods on that water.
- •Camec's card for its 13kW instant unit says there is no anode to replace.
- •Jayco's service checklist says to replace the anode where applicable.
Bypass, saver and diverter valves: what each one does
Bypass valves
A bypass sends water around the heater, so the heater is closed off from the rest of the plumbing. Makers describe it for winterising, when the van is stored through frost or the plumbing takes winterising fluid.
A valve on each side of the heater closes it off, and a third valve opens the bypass line. Layouts differ, so check your kit. Turn the heater off before you change the valves. Return them to normal use before you switch it on again.
- •Suburban SW: use the bypass kit to close off the heater and drain it, and leave it closed off if antifreeze goes through the plumbing. Suburban says antifreeze can be very corrosive to the anode.
- •Truma AquaGo comfort: winterising with fluid is only possible with an installed bypass kit, which is sold separately. Truma's steps are to close valves A and B and open valve C, then drain the unit.
Saver valves
A saver valve saves the cold water that sits in the hot line while you wait for hot water. These two sellers' descriptions show the two ways it is done.
- •Enviro Save: a thermal valve under the sink or basin. It returns cooler water to the cold supply, then switches to hot at the set temperature. It suits one wet area, and needs at least 4 litres a minute.
- •Showermiser: a unit at the shower. You flip a lever and the cold water goes back to the water tank. A tube changes colour when the water is hot.
Ask a licensed plumber or your installer whether a valve suits your plumbing and carries WaterMark approval.
Diverter valves
Sellers use this name for two parts. RecPro, a US seller, uses it for the valve that sends water around the heater, which is a bypass. The Showermiser kit uses it for the lever valve at the shower, which is a saver. Ask the seller which job the part does before you buy it.
Tempering and pressure limiting valves
- •A tempering valve mixes hot water with cold to cool it. RMC sells one set to a maximum of 50 degrees, and John Guest sells one preset to 47 degrees.
- •Suburban's manual says a tempering valve or similar device must be installed between the heater's outlet and any tap. Its tank holds water above 60 degrees, and it warns that water above 60 degrees can burn severely. Suburban says to always feel the water before you bathe or shower.
- •A pressure limiting valve lowers mains pressure before it reaches the van. Outback Equipment lists one preset to 350 kilopascals (kPa).
- •Suburban says mains pressure must be limited to about 350 kPa or the warranty is void. Swift lists a maximum inlet pressure of 400 kPa.
Servicing a caravan hot water system
Have a licensed person do the gas and electrical work. These are the jobs the manuals give to owners.
Operate the relief valve every 6 months
Suburban, Swift and Truma's UltraRapid manuals each say to operate this valve at least once every 6 months. It clears lime deposits and shows the valve is not blocked. The manuals warn of danger if you skip it. The water can be very hot, so let the heater cool first and stand clear of the outlet. To operate it, use its lever so water runs, then let the valve close. Truma's test lever must go back to close. Never plug or cap the outlet, as Suburban warns.
Suburban says a small drip can be normal as pressure builds, and that constant leaking may show a problem. Ask your dealer about constant leaking.
Drain the tank before storage or frost
Turn the heater off first, on gas and on 240V. When you finish, close the drain or refit the anode, using thread sealant on Suburban's. Then refill it before you switch it on again. The tank is full when water runs from a hot tap.
- •Suburban SW: on an element model, turn the breaker off first. Turn off the gas and the water pump, and open both taps. Let it cool, then remove the anode to drain it. Refit the anode, then refill before you light it again.
- •Truma UltraRapid: turn off the pump, let it cool and open the hot taps. Move the drain lever to drain, and check 14 litres have come out.
- •Swift: when you store the van, drain through the ball valve in the cold line, or run out at least 40 litres when you next use it. In freezing conditions, Swift says to check water flows from a hot tap before you turn it on.
Flush and descale
- •Suburban SW: drain and flush regularly. Suburban says outback water needs it more often than city water, and that bore water must not be used.
- •Swift: do not fill directly from untreated bore water.
- •Truma UltraRapid: descale at least twice a year. Products containing chlorine are unsuitable.
- •Truma AquaGo: use only Truma's decalcifying tablets.
Book the service
- •Truma says to have the complete gas installation checked by a licensed person at least every 2 years.
- •Western Australia says a licensed gas fitter should service installed gas appliances to the maker's instructions, after long trips, or at least annually.
- •Jayco says to service its vans every 10,000 kilometres or 12 months, through a Jayco dealer or authorised repairer.
Queensland requires a licence or authorisation for any gas work in a caravan, including servicing. New South Wales requires a qualified person to do the work or to immediately supervise it. Check your state's gas regulator if you live elsewhere.
If you smell gas, Suburban says to put out any flames, touch no electrical switches, get everyone out of the van and shut off the gas at the bottle. Have a licensed gas fitter fix it before anyone uses the heater.
Who to call
- •Truma: Leisure-Tec Australia, 1300 07 2018.
- •Camec: 1300 422 632 (1300 4CAMEC).
- •Swift: 03 9359 3068.
- •Suburban: your dealer. The manual names Coast to Coast RV Services on its warranty.
- •Jayco: 1800 331 601.
Our recall guide shows where to check for safety recalls on your van and its fitted gear.
Common questions
Why is my caravan hot water not working on 240V?
Check the van is on site power, then check the circuit breaker or safety switch your heater's manual names. The heater's tank must be full before the element goes on. If a thermal cut-out has tripped, call a qualified person.
Can I reset the thermal cut-out myself?
No. Leave it until the heater has been serviced. Suburban, Truma and Swift each say a tripped cut-out on the 240V side shows a possibly dangerous situation. Each says to have a qualified person service the heater first.
Does my caravan hot water system have an anode?
Check your heater's manual. Suburban's SW tanks have a magnesium or aluminium anode. Swift's stainless tank has an anode tube against bacteria from untreated bore water. Camec's card for its 13kW instant unit says there is no anode to replace.
How often should I check the anode?
Suburban says to check the anode in its SW tanks every 6 months, and to replace it below 50% of its original diameter. Swift says its anode does not need changing on a regular basis.
What does a hot water bypass valve do?
It sends water around the heater so the heater is closed off. Suburban and Truma both describe it for winterising. Truma says its AquaGo can only be winterised with fluid if a bypass kit is fitted.
What does a caravan water saver valve do?
It saves the cold water that sits in the hot line while you wait for hot water. The Enviro Save returns it to the cold supply. The Showermiser sends it back to the water tank when you flip a lever.
Do instant hot water systems run on 240V?
The Suburban ST-60, Truma AquaGo and Camec 13kW in this guide run on gas with 12V power. Check your unit's manual if yours is a different model.
How hot does caravan hot water get?
It depends on the heater. Suburban's SW tanks hold above 60 degrees, and Truma's UltraRapid limits at about 70 degrees. Swift's tank stops at 78 degrees and is tempered. Truma's AquaGo standard setting is 49 degrees. Suburban warns that water above 60 degrees can burn severely, so feel the water before you shower.