Truma Combi D4 diesel heater for motorhomes, campervans and caravans: heating and hot water from the diesel in your vehicle's tank
The Truma Combi D4 diesel heater combines warm-air heating and a 10-litre water heater in a single unit. Truma designed it for small and medium-sized motorhomes, caravans and campervans, and it takes its fuel from the vehicle's own tank, so you do not need gas cylinders.
This Truma Combi D4 is a next-generation model and works in four automatic stages, from 1000 W to 4000 W. Truma also lets you use it while driving and approves it for HVO, the synthetic diesel in the EN 15940 standard. According to the brand, the built-in pressure sensor lets it heat at any altitude.
Before you choose it, bear three things in mind. Firstly, the Truma Combi D4 diesel heater comes with the iNet X Panel or the iNet X Panel 2. Secondly, only a qualified technician can fit it. Thirdly, the box does not contain the exhaust system, the water connection set or the tank connection kit. If you want to see more from the brand, browse the Truma products in our shop.
Benefits of the Truma Combi D4 diesel heater
- No gas cylinders: it takes the diesel from the vehicle's tank, using the connection kit that matches your chassis.
- Heating and hot water in a single unit, with a built-in 10-litre water tank.
- In winter, heating and water run at the same time; in summer, the water heats up independently of the heating.
- Four power stages, from 1000 W to 4000 W (max. 4.4 kW), which the unit selects by itself according to the difference between the set temperature and the ambient temperature.
- Truma permits operation while driving, with a fan-assisted burner.
- Runs on EN 590 diesel and HVO to EN 15940, with a maximum of 7% biodiesel.
- According to Truma, the built-in pressure sensor allows it to heat at any altitude.
- According to the brand, more efficient combustion saves battery power and diesel.
- 4.3" touchscreen, iNet X App via Bluetooth and up to 6 timers.
Is it compatible with your motorhome, campervan or caravan?
This matters because Truma only approves this heater for installation in motorhomes of vehicle class M1 and in caravans of class O. So a campervan needs motorhome approval. If it is a commercial vehicle (class N), Truma prohibits installation.
| Requirement | What Truma says |
| Approved vehicles | Motorhomes of class M1 and caravans (trailers) of class O. |
| Installation prohibited | Coaches and buses (M2 and M3), commercial vehicles (class N), boats and other watercraft, hunting or forestry huts, weekend homes, canopies, and trailers or vehicles for dangerous goods. |
| Vehicle size | Small and medium-sized. For large vehicles, Truma points to the Combi D6. |
| While driving | Permitted. Do not let the vehicle's tank drop to reserve, and do not use the unit while refuelling. |
| Fuel | From the vehicle's tank, with the connection kit recommended for each model (see the tables below). |
| Room temperature sensor | External; the vehicle manufacturer decides where the sensor goes, depending on the vehicle type. |
| Window switch | Required if the wall cowl is below a window that opens or within 30 cm of one (EN 1949). |
| Mains water | Pressure reducer and non-return valve when connecting to a mains water supply. |
| Warm-air ducts | Essential: the unit cannot work without them. |
Space matters because the unit measures 510 x 450 x 300 mm and Truma asks for a minimum installation space of 540 x 500 x 350 mm, plus room for the connections and the drain valve. While the heater runs, keep the wall cowl at least 1 m from any wall, building, tent or vehicle, so that it can draw in fresh air and expel the gases.
Tank connection kit for the Truma Combi D4 diesel heater, by vehicle
Because the heater takes its diesel from the tank, Truma recommends a connection kit according to the vehicle. The brand also warns that the assignment is subject to change and extension. So this first table covers the Fiat Ducato 250, Citroën Jumper, Peugeot Boxer, Iveco Daily, Renault Master and Renault Trafic; the numbers in brackets refer to the notes at the end.
| Vehicle and tank | Without prepared fuel take-off | With prepared take-off | Prepared take-off already in use (e.g. by an auxiliary heater) |
| Fiat Ducato 250 (1) / Citroën Jumper (1) / Peugeot Boxer (1), 90 l, up to Euro 5 | TAS 01 / 09 | with SAE: no kit, direct connection (4); without SAE: TAS 03 | TAS 10 (3) |
| Fiat Ducato 250 / Citroën Jumper / Peugeot Boxer, 90 l, from Euro 5 | TAS 01 / 09 / 11 | with SAE: no kit, direct connection (4); without SAE: TAS 03 | TAS 10 (3) |
| Fiat Ducato 250 / Citroën Jumper / Peugeot Boxer, 120 l | TAS 01 / 11 | with SAE: no kit, direct connection (4); without SAE: TAS 03 | TAS 10 (3) |
| Iveco Daily, from 2007 (identical with Euro chassis) | TAS 01 | with SAE: no kit, direct connection (4); without SAE: TAS 03 | TAS 06 |
| Renault Master up to 04/2010 | TAS 01 / 09 (2) | without SAE: TAS 03 | TAS 10 (3) |
| Renault Master from 05/2010, 80 / 100 l | TAS 06 (6) | – | TAS 10 (3) |
| Renault Trafic from 2014 | TAS 06 (6) | – | TAS 10 (3) |
As you can see, a Fiat Ducato with a factory-prepared tank take-off and an SAE connector needs no kit, because Truma's fuel line, sold by the metre, is enough. For the other vehicles in the tables, however, Truma assigns a specific connection kit.
Tank kit for Ford Transit, Mercedes-Benz Sprinter, Volkswagen and MAN TGE
Then comes the second part of Truma's list, which covers the remaining chassis. Look closely at the columns, because the middle column applies only when the vehicle has the prepared fuel take-off. If you have to lower the tank to fit the kit, note (2) says so.
| Vehicle and tank | Without prepared fuel take-off | With prepared take-off | Prepared take-off already in use (e.g. by an auxiliary heater) |
| Ford Transit, 80 l | – | TAS 05 (5) | TAS 06 |
| Mercedes-Benz Sprinter 906 / 907 (2), 75 l | TAS 01 (2) | TAS 05 (2) | TAS 06 |
| Mercedes-Benz Sprinter 906 / 907 (2), 100 l | TAS 01 (2) | TAS 05 (2) | TAS 06 |
| Volkswagen Crafter up to 2016 (2), 75 l | TAS 01 (2) | TAS 07 (2) | TAS 06 |
| Volkswagen Crafter up to 2016 (2), 100 l | – | TAS 07 (2) | TAS 06 |
| Volkswagen Crafter from 2017 (2), 63 / 75 l | TAS 01 (2) | TAS 07 (2) | TAS 10 (3) |
| Volkswagen T5 | TAS 01 (2) | TAS 07 (2) | TAS 06 |
| Volkswagen T6 | TAS 01 (2) | TAS 07 (2) | TAS 06 |
| MAN TGE | TAS 01 (2) | TAS 07 (2) | TAS 06 |
This is the only list of vehicles Truma publishes, so read it as a kit recommendation for each model, not as a guarantee that you can fit the heater to any other chassis.
Notes and part numbers for the tank connection kits
The notes explain the conditions for each row, while the part numbers show which Truma code matches each TAS kit.
| Note | What Truma says |
| (1) | From Euro chassis. |
| (2) | It may be necessary to lower the vehicle's tank to fit the connection kit. |
| (3) | For connection to fuel lines fitted as standard on the vehicle, Ø 5 x 1.5 mm. |
| (4) | Direct connection of the Truma fuel line to the SAE connector fitted as standard on the vehicle. |
| (5) | If the vehicle has the ‘Camper package’ option (from August 2009). |
| (6) | Approval for fitting to the vehicle's return line covers only the chassis listed; you must fit the kit to that line following Renault's fitting guidelines. |
Each kit also comes with detailed fitting instructions, and the codes are as follows.
| Truma part number | Tank connection kit |
| 34601-01 | TAS 01: you have to remove the level sensor. |
| 34601-03 | TAS 03. |
| 34601-05 | TAS 05. |
| 34601-06 | TAS 06. |
| 34601-07 | TAS 07. |
| 34601-09 | TAS 09: 280 mm pick-up lance; you do not need to remove the level sensor. |
| 34601-10 | TAS 10. |
| 34601-11 | TAS 11: 330 mm pick-up lance; you do not need to remove the level sensor. |
Technical specifications of the Truma Combi D4 diesel heater
These are the figures Truma publishes for the next generation, so you can compare power, fuel consumption and heat-up times before you decide.
| Specification | Value |
| Manufacturer and official name | Truma, Combi D 4 (next generation) |
| Fuel | diesel to EN 590 and diesel to EN 15940 (HVO); it does not accept more than 7% biodiesel |
| Rated heat output on diesel (automatic stages) | 1000 W / 2000 W / 3000 W / 4000 W (max. 4.4 kW) |
| Fuel consumption | 0.1 – 0.4 l/h (0.1 l/h at an average output of 1000 W) |
| Water capacity | 10 litres |
| Water heating time from approx. 15 °C to approx. 60 °C | hot water only: approx. 24 min (EN 15033); heating and hot water: approx. 80 min |
| Pump pressure / system pressure | max. 2.8 bar / max. 4.5 bar |
| Air flow | max. 287 m³/h with 4 warm-air outlets |
In practice, the output rises and falls by itself in stages, and consumption stays at 0.1 l/h when the unit holds an average output of 1000 W. You will find the electrical consumption, dimensions and approval further down.
Electrical consumption, dimensions, weight and approval
The unit runs on 12 V and, during the 2 minutes of switching on and off, it draws a typical current of 20 A, with possible peaks of up to 80 A, as the table shows.
| Specification | Value |
| 12 V consumption, heating + water tank | 0.4 – 8.1 A |
| Heating the water tank only, at 12 V | 0.5 A |
| Consumption during 2 minutes when switching on and off | typical continuous current of 20 A, with possible peaks of up to 80 A |
| Quiescent current | approx. 0.001 A |
| FrostControl heating element (optional) | max. 0.4 A |
| Dimensions (L x W x H) | 510 x 450 x 300 mm |
| Minimum installation dimensions | 540 x 500 x 350 mm |
| Type approval | E1 122R–00 0232 and E1 10R–06 5277 |
| Weight | 14.8 kg (with peripherals: 16.0 kg) |
| Truma part numbers and EAN | iNet X Panel: 33406-20, EAN 4052816042824; iNet X Panel 2: 33407-20, EAN 4052816050744 |
Truma counts the control panel, the FrostControl, the diesel pump with its bracket, the flexible hoses, the cables and the fixings as peripherals, so the weight with peripherals is higher. Without peripherals, the Truma Combi D4 diesel heater weighs the same as the Combi D6: 14.8 kg.
How the Truma Combi D4 diesel heater works
Inside the unit, a circulation fan draws in cold air from the interior, passes it through the heat exchanger and then returns it warm to the living area through the warm-air ducts, which end in four outlets. The unit chooses the power stage itself, since it compares the temperature set on the control panel with the ambient temperature.
Heating, hot water or both functions at once
With the Truma Combi D4 diesel heater you do not need to fill the water tank to heat the living area; if you do fill it, the water heats up on its own. If you only need hot water, for example in summer, the unit heats the water separately and switches the burner off once it reaches the chosen temperature.
But bear in mind that, according to Truma, the water in the tank can reach 70 °C. That is why the brand recommends a mixer tap or a thermostatic mixing valve, because separate hot and cold taps carry a risk of scalding.
While driving and with HVO
The burner is fan-assisted so that it works correctly on the move, and Truma lets you use it while driving. However, do not let the vehicle's tank get close to the reserve mark: the take-off would draw in air, the supply would turn irregular and combustion would leave thick smoke and odours. Do not use the heater while refuelling either.
Both EN 590 diesel and EN 15940 synthetic diesel work as fuel. Truma states that the heater is approved for pure HVO (for example HVO100) and for blends of it with fossil diesel and B7. However, it does not accept blends with more than 7% biodiesel (B10, B20, B30 or pure biodiesel), nor used oil, rapeseed oil, alcohol or petrol.
At temperatures below 0 °C, problems can arise if you keep refuelling with summer diesel, and below -20 °C you must check that the winter diesel is suitable for that range. After refuelling with winter diesel, also let the unit run for at least 15 minutes to fill the lines.
iNet X Panel or iNet X Panel 2: what changes on the Combi D4
You choose the control panel when you buy. Both control the heating, the air-conditioning system and the Truma LevelControl indicator with a 4.3" touchscreen, and you can also operate both from the free iNet X App via Bluetooth. According to Truma's data, this is the only thing that changes:
| Item | iNet X Panel | iNet X Panel 2 |
| 4.3" TFT-LCD touchscreen | resistive | capacitive |
| Weight | approx. 150 g | approx. 190 g |
| Dimensions (L x W x H) | 96.7 x 120.1 x 31 mm | 89 x 118 x 31 mm |
| Low-battery warning in the app | Not published by Truma | yes: the app warns you when it needs replacing |
Everything else is the same. Both run on 12 V (8 V to 16 V), use 1.5 W, work with TIN, CI and CAN buses and Bluetooth Low Energy, and withstand -30 °C to 60 °C. The battery is a CR 2032 lasting about 8 years, while the protection rating is IP20 at the front and IP00 at the back.
Both panels also have physical Home and Back buttons. With the app, you can also connect up to 3 mobile phones at once and set up to 6 timers. Updates install from the app, over internet and Bluetooth, and can take up to 15 minutes.
But remote control needs the iNet X Connect module, which is optional and not included. According to Truma, the iNet X Connect does not work in Andorra, Bosnia and Herzegovina, Kazakhstan, Moldova, Ukraine, Turkey, Belarus or Russia.
Installation and fitting: a job for qualified technicians
Only qualified and authorised persons, that is, technical personnel, may fit, repair and test this Truma product. If you are not a technician, you must not open the unit, install it in another vehicle, modify it or repair it yourself. So leave the fitting to a technician.
The installer will also need to complete what the box does not contain: the exhaust system, the water connection set with the FrostControl valve, the tank connection kit and the warm-air ducts. They will also place the yellow warning stickers somewhere clearly visible in the vehicle, for example on the wardrobe door.
FrostControl and frost risk
The FrostControl, which comes in the water connection set (not included), is a power-free safety and drain valve: below about 3 °C it opens by itself and empties the water tank, and you can only close it by hand when the valve is at least about 7 °C. You can also open it to clean the tank, when there is a risk of frost or before winter storage.
If you leave the vehicle unused in cold weather, empty the water tank, because Truma excludes frost damage from the warranty. To fill the tank sooner in cold climates, there is also an optional heating element that brings the valve up to about 10 °C.
What's in the box and the accessories you need
This is what comes in the box, depending on the variant you choose. The unit also needs warm-air ducts to work, but they do not appear in the contents.
- iNet X Panel variant: heater with room temperature sensor, iNet X Panel, 6 m control panel cable, fuel line, metering pump and fixings.
- iNet X Panel 2 variant: heater with room temperature sensor, iNet X Panel 2, control panel cable, fuel line, metering pump and fixings.
The following items do not come in the box or with the heater, so you will need to add them to your installation plan:
- Exhaust system: Combi D pipe kit with silencer and ZR 80 wall cowl (inner and outer parts).
- Water connection set FC TB (36100-01) or FC JG (36100-02), which is the one that includes the FrostControl valve.
- Fuel tank connection kit, depending on the vehicle.
- FrostControl heating element, optional.
- iNet X Connect remote module, optional.
- Warm-air ducts and air outlets.
Official Truma part numbers: exhaust and water
These are the part numbers Truma lists as accessories for the next-generation Combi D, starting with exhaust and water.
| Truma part number | Official accessory |
| 34502-01 / -02 / -03 / -04 | Complete Combi D pipe kit, with exhaust silencer 600 and Ø 80 mm combustion-air pipe, in lengths of 0.6 / 0.7 / 1.0 / 1.5 m. If you have to shorten it, you need the 35 mm locking-washer tool to fit the replacement washer (34020-45200). |
| 36140-01 | Inner part of the ZR 80 cowl with clamps (without outer part). |
| 36151-09 / 36151-10 | Outer part of the ZR 80 cowl, black or anthracite; Truma recommends these two heat-resistant variants for the Combi D (E). |
| 36100-01 | FC TB water connection set: FrostControl TB power-free drain valve, TB elbows for Ø 10 mm flexible water hoses and black flexible PVC hose (TB = barbed connection). |
| 36100-02 | FC JG water connection set: FrostControl JG power-free drain valve, JG elbows for Ø 12 mm rigid pipe and clear flexible PVC hose (JG = John Guest system). |
Official Truma part numbers: fuel, cowl and extras
This second table covers fuel, cowl conversion, warm air and the other extras the brand also lists.
| Truma part number | Official accessory |
| 34020-01315 | 5 x 1.5 mm fuel line for the next-generation Combi D, sold by the metre. With it and the unit's own components, you can connect a vehicle such as a Fiat Ducato with a factory-prepared tank take-off and SAE connector, without further adaptations. |
| 34020-01669 | Wall cowl conversion kit for the Combi D (E): converts from the Combi D to the next generation and lets you keep using the old side-wall cut-out. |
| 34092-01 | Black BGC elbow for connecting directly to the warm-air outlets (outlet for Ø 65 mm or Ø 72 mm pipes). |
| 70070-01 | FrostControl heating element with 1.5 m cable, to fill the water tank faster regardless of the ambient temperature. |
| 47000-00140 | Alternative iNet X room temperature sensor (e.g. FFC2), for direct connection to the iNet X Panel control panel. |
| 34030-34700 / 34020-01581 | Window switches (the second one narrow) for automatic switch-off of the heating; the 34030-34700 suits common hinged caravan windows. |
These part numbers come from Truma's official list and serve as a guide for your installer, but we only quote them here and do not offer them as part of the box.
Who is the Truma Combi D4 diesel heater for?
The Truma Combi D4 diesel heater suits you if your vehicle is an M1 motorhome or a class O caravan, small or medium-sized, and you want heating and hot water without relying on gas cylinders. These are the profiles it fits best:
- Anyone who travels in winter and wants heating while driving too.
- Anyone who prefers to refuel with a single fuel, the one in the vehicle's tank.
- Anyone who wants hot water on board without adding a separate water heater.
- Anyone who wants to control the temperature from a touchscreen or from a mobile phone.
- Anyone who drives a campervan approved as a motorhome and has identified their tank kit.
However, if the vehicle is a commercial vehicle (class N), a bus or a boat, Truma does not authorise installation. If you are comparing equipment, you can also have a look at the air conditioning and cooling section.
Maintenance, cleaning and warranty for the Truma Combi D4 diesel heater
A little routine extends the life of the unit, so with the Truma Combi D4 diesel heater it is worth following these guidelines from the manual:
- If it contains water, heat it for about 30 minutes at least once a month.
- Operate the FrostControl valve at least twice a year to release limescale and prevent blockages.
- Check the exhaust gas system at regular intervals and at least every 2 years.
- Check the double exhaust pipe, the unit's mounting and the wall cowl, especially after long journeys.
- Keep the cowl free of snow, ice, leaves, tarpaulins and nests, and do not spray it with pressurised water.
- Clean the outer part of the cowl with a soft sponge and an outdoor plastic cleaner.
- If smoke comes out of the cowl for more than 1 minute, switch the unit off.
Water tank and starting up after a break
Firstly, you must sterilise and descale the tank regularly. Camping cleaning products are fine, while for limescale you can use commercial descalers, vinegar essence or citric acid. Truma also recommends heating the water to 70 °C periodically to curb legionella and other micro-organisms.
To do this, select diesel mode, set the water to 60 °C and switch the unit on: the residual heat then takes the water up to 70 °C. Leave it on for at least 30 minutes without drawing off any hot water. After a long break, charge the batteries, then rinse the unit and hoses with drinking water and check that the cowl has no damage or nests.
Replace 12 V fuses only with original Truma parts, and only while the battery is disconnected. Finally, any repair is a job for a specialist technician or Truma's after-sales service. If you park in an enclosed space, switch the heating off, deactivate the timer and do not switch it on remotely with the app, because of the risk of exhaust-gas poisoning.
Manufacturer's warranty
As the manufacturer, Truma grants a 24-month voluntary warranty against material or manufacturing defects, valid in the European Union, the United Kingdom, Iceland, Norway, Switzerland and Turkey. This warranty does not, however, affect the consumer's statutory rights against the seller. The control panel also has 24 months of cover.
Frequently asked questions
What is the Truma Combi D4 diesel heater and what is it for?
The Truma Combi D4 diesel heater is a combi boiler: a warm-air unit with a 10-litre water heater, from Truma's next generation. It heats the living area and the water with the diesel from the vehicle's tank, so it uses no gas cylinders. It suits small or medium-sized motorhomes, caravans and campervans, as long as the campervan has motorhome approval.
Can I use the Truma Combi D4 diesel heater while driving?
Yes. Truma allows operation while driving, and the fan-assisted burner works properly on the move. Do not let the vehicle's tank drop to reserve, though, because the unit sucks in air and the fuel supply turns irregular, and do not use the heater while refuelling.
Which tank connection kit does my Fiat Ducato or Mercedes Sprinter need?
It depends on the year, the tank and whether the fuel take-off is prepared. On a Fiat Ducato 250 with factory take-off and SAE connector, Truma's fuel line is enough; without the connector, you need the TAS 03. A Sprinter 906 / 907 takes the TAS 01, the TAS 05 with a prepared take-off or the TAS 06 if it is in use; you may have to lower the tank.
Can I fit it in my campervan?
Only if the van has motorhome approval, that is, class M1. Truma does not allow installation in commercial vehicles (class N), buses or boats. Truma also designed this Combi D4 for small and medium-sized vehicles; for large ones, it points to the Combi D6.
What do I need to buy separately to install the Truma Combi D4 diesel heater?
The box does not include the exhaust system (Combi D pipe kit and ZR 80 cowl), the water connection set with FrostControl or the tank connection kit, so you must add them. Nor does it include the warm-air ducts, without which the unit does not work. A qualified technician must also do the fitting.
