Truma Combi
(E)
The Truma Combi (E) is a fan-assisted liquefied gas warm-air heater with an integrated 10-litre hot water boiler and, in 'E' variants, additional heating elements for 230V electrical operation. It provides simultaneous or independent space heating and water warming for caravans and motorhomes.
View official manual on manufacturer's site ↗Technical Specifications
Operating Voltage12V DC / 230V AC
Power Consumption1.2 – 6.5 A (at 12V), 3.9 A (900W) or 7.8 A (1800W) (at 230V)
Gas Or Pressure30 mbar
Fuse Ratings10 A quick-acting (12V), 10 A quick-acting interrupting capacity H (230V)
Dimensions Cutout450 x 300 mm (heater dimensions approx. 510 x 450 x 300 mm)
Master Troubleshooting & Diagnostics Matrix
| Error Code / Indicator | Symptom / Meaning | Possible Cause | Step-by-Step DIY Fix | Suggested Actions |
|---|---|---|---|---|
N/A | The water's taking a really long time to heat up | Water container furred | Descale the water system with a commercial descaler, vinegar essence, or citric acid, per the maintenance instructions. | DIY Safe |
N/A | Water's running off - the boiler won't fill | Safety / drain valve open | Close the safety/drain valve - check the rotary switch is on 'operation', then push the button in until it clicks. | DIY Safe |
N/A | The boiler won't drain, even with the safety/drain valve open | Safety / drain valve drainage socket blocked | Check opening for soiling such as slush, ice, or leaves, and remove obstruction if necessary. | DIY Safe |
N/A | Water's dripping or flowing from the safety/drain valve's drainage socket | Water pressure too high | Check the pump pressure stays under 2.8 bar, fitting a pressure reducer if it's on mains water. | DIY Safe |
N/A | The FrostControl opens after the heater's been switched off | Temperature at the FrostControl dropped below approximately 3 °C, causing it to open automatically | Switch the heater on to warm the installation compartment - without it running, the FrostControl won't close again until it reaches roughly 7°C, unless an optional FrostControl heating element is fitted. | DIY Safe |
N/A | The FrostControl won't close any more | Either the FrostControl's own temperature is below roughly 7°C, or the rotary switch isn't set to operation | Switch the heater on to bring the surroundings above 7°C, or turn the FrostControl's rotary switch to operation and press the pushbutton in until it clicks. Contact an authorised service agent if this doesn't fix it. | DIY Check / Tech Fallback |
W255H | Combi Gas Heater control panel displays fault code W255H | Heater has no 12V power supply. | Ensure that the 12V power supply is available. | DIY Safe |
W255H | Combi Gas Heater control panel displays fault code W255H | No connection between heater and control panel. | Make connection between heater and control panel. | DIY Safe |
W302H / W418H | Combi Gas Heater control panel displays fault code W302H or W418H | Low voltage - the 12V supply to the heater is too low. | Charge the battery. If necessary, replace the old battery. | DIY Safe |
W303H / W411H | Combi Gas Heater control panel displays fault code W303H or W411H | Risk of low voltage - battery voltage is too low (below 10.4V). | Charge the battery. | DIY Safe |
W401H | Combi Gas Heater control panel displays fault code W401H | Summer mode with empty water container. | Switch the heater off and allow it to cool. Fill the boiler with water. | DIY Safe |
W402H | Combi Gas Heater control panel displays fault code W402H (warm air temperature exceeded) | Not all warm air ducts are connected. | Check whether the 4 warm air ducts are connected. | DIY Safe |
W402H | Combi Gas Heater control panel displays fault code W402H (warm air temperature exceeded) | Warm air outlets blocked. | Check the individual outlet openings. | DIY Safe |
W402H | Combi Gas Heater control panel displays fault code W402H (warm air temperature exceeded) | Circulated air intake blocked. | Remove the circulated air intake blockage. | DIY Safe |
W407H | Combi Gas Heater control panel displays fault code W407H | No 230V operating voltage. | Restore 230V operating voltage. | DIY Safe |
W407H | Combi Gas Heater control panel displays fault code W407H | 230V fuse defective. | Replace the 230V fuse (see Combi operating instructions). | DIY Safe |
W408H | Combi Gas Heater control panel displays fault code W408H | No gas supply in Mix mode. | Check the gas supply. See fault code E507H (electronic heating continues in Mix mode). | DIY Safe |
W412H | Combi Gas Heater control panel displays fault code W412H | Window above the cowl is open (window switch). | Close the window. | DIY Safe |
E507H / E516H / E517H | Combi Gas Heater control panel displays fault code E507H, E516H, or E517H | Gas cylinder empty. | Replace the gas cylinder. | DIY Safe |
E507H / E516H / E517H | Combi Gas Heater control panel displays fault code E507H, E516H, or E517H | The gas cylinder or its quick-acting valve is closed. | Check the gas supply and open the valves. | DIY Safe |
E507H / E516H / E517H | Combi Gas Heater control panel displays fault code E507H, E516H, or E517H | Gas pressure regulation system iced up. | Use a regulator heater (EisEx). | DIY Safe |
E507H / E516H / E517H | Combi Gas Heater control panel displays fault code E507H, E516H, or E517H | Butane content in the gas cylinder too high. | Use propane - butane is unsuitable for heating, particularly at temperatures below 10C. | DIY Safe |
E507H / E516H / E517H | Combi Gas Heater control panel displays fault code E507H, E516H, or E517H | Combustion air infeed or exhaust outlet is sealed. | Check the openings for anything blocking them (slush, ice, leaves, etc.) and clear it away. | DIY Safe |
E507H / E516H / E517H | Combi Gas Heater control panel displays fault code E507H, E516H, or E517H | Gas pressure regulation system faulty. | Inspect and, if necessary, replace the gas pressure regulation system. | DIY Safe |
E607H | Combi Gas Heater control panel displays fault code E607H | Maximum number of fault resets reached. | Wait 15 minutes and reset the fault. | DIY Safe |
E621H | Combi Gas Heater control panel displays fault code E621H | Room temperature sensor or cable faulty. | Inspect the room temperature sensor cable, replace if faulty. | DIY Safe |
E624H | Combi Gas Heater control panel displays fault code E624H | Frost Control heating element has a short circuit. | Disconnect the heating element plug from the electronic control unit and replace the heating element. | DIY Safe |
E632H | Combi Gas Heater control panel displays fault code E632H | Overheating protection has been triggered. | Reset overheating protection (see Combi operating instructions). | DIY Safe |
E514H | Combi Gas Heater control panel displays fault code E-514-H | The vehicle was powered down at the master switch/control panel before the correct shutdown procedure was completed (the control panel's rotary push button must be held for 3 seconds to power it down first, before powering down the van at the master switch). | Keep the power on and wait until the error code stops flashing (approx. 15 minutes), then press the rotary push button twice to continue as normal. To avoid recurrence, always press and hold the rotary push button for 3 seconds to power down the control panel before powering down the van at the master switch. | DIY Safe |
#41 | Combi Gas Heater control panel displays fault code #41 | Electronics blocked. | Get in touch with Truma's service team. | Professional Intervention Required |
#43 | Combi Gas Heater control panel displays fault code #43 | Overvoltage above 16.4V | Check the battery voltage and the voltage sources feeding it, such as the charger. | DIY Safe |
Frequently Asked Questions
Q: Can the Combi be operated without water in the tank?
Yes, interior heating is possible both with and without water content, depending on the operational setting.
Q: I can smell gas inside the vehicle - what should I do?
Straight away, remove any ignition sources - put out naked flames, don't touch electrical switches, phones or radios, and don't start the engine. Open the windows and doors, get everyone out of the vehicle, shut off the gas cylinders or external gas supply, and have the whole system checked and repaired by a qualified expert.
Q: How do I protect the water boiler from frost damage?
If the vehicle is not in use during freezing periods, you must completely drain the water container via the safety/drain valve (FrostControl or manual drain valve). The system does not feature an internal active frost protection mechanism that prevents freezing without draining.
Q: Can the Truma Combi be operated while driving?
Yes, as long as a suitable safety shut-off device - for example a gas pressure regulator like Truma's MonoControl CS - is fitted in line with UN ECE Regulation 122, to stop gas escaping uncontrolled in a crash.
Q: How do I reset the 230V overheating protection on Combi E models?
Let the heater cool, remove the cover over the electrical connector, and press the switch's reset button.
Q: What do the different LED colors mean for the operating mode?
Green means operational, and yellow indicates the warm water heat-up phase.
Q: What electrical power levels are available in electrical mode?
You can select 900 W or 1800 W depending on the setting.