Truma Combi 4 gas heater for your motorhome, caravan or campervan: 4000 W of gas heating and hot water in one unit
The Truma Combi 4 gas heater combines heating and hot water in a single gas appliance for your motorhome, caravan or campervan. According to Truma, this saves space and weight in the vehicle, because the heater itself houses the 10-litre stainless steel tank.
It runs on LPG only (propane or butane at 30 mbar) and works at two power levels, 2000 W and 4000 W, which the unit chooses depending on the heat you need. Truma suggests it for small and medium-sized vehicles, with a gas consumption of 160 – 335 g/h. If you are looking for a gas heater for a caravan of that size, this Combi 4 is Truma's answer.
It comes with the iNet X Panel control panel, which you operate from the touchscreen or from your phone. Note, though, that the box does not include the exhaust system or the water connection set, because you order both separately, and fitting is a job for qualified technicians.
Benefits of the Truma Combi 4 gas heater
- Two functions in one unit: it heats the vehicle and, at the same time, the water in the tank.
- Four warm-air outlets that, according to Truma, distribute the heat optimally around the living space.
- Automatic output: it switches by itself from 2000 W to 4000 W depending on the difference between the set temperature and the ambient temperature.
- 10-litre stainless steel tank and, according to Truma, a short water heating time.
- It heats the living space even if the water tank is not full.
- Fan-assisted burner, designed to work while you drive too, provided the gas supply has a MonoControl CS regulator or another safety shut-off device.
- Low consumption: 160 – 335 g/h of gas and, according to Truma, low energy consumption.
- Practically silent and extremely economical in operation, according to Truma's official website.
- Part of the Truma iNet X system: you control it from the panel or from the app.
- Weighs 14.4 kg without water, the lowest weight in the gas Combi range, which it shares with the Combi 6.
Is it compatible with your motorhome, campervan or caravan?
According to Truma, the Truma Combi 4 gas heater is approved only for motorhomes of vehicle class M1 and for caravans of class O, provided the gas installation complies with standard EN 1949. A campervan therefore needs approval as a motorhome to take it; Truma does not permit fitting it in a commercial vehicle (class N).
Truma also sorts its Combi heaters by vehicle size: small, medium and large. That is why the Combi 4 corresponds to small and medium-sized vehicles, while for a large one the range points to the Combi 6. Then go through the next two tables with your installer.
Vehicle, space and power supply for the Truma Combi 4 gas heater
First of all, measure the space, because the unit and its minimum installation space determine where you can fit it. Truma also states clearly which vehicles you cannot install it in.
| Requirement | What Truma says |
| Permitted vehicles | Motorhomes of vehicle class M1 and caravans of class O, with the gas installation carried out to standard EN 1949. |
| Vehicles not permitted | Coaches and buses (M2 and M3), commercial vehicles (class N), boats and other watercraft, hunting or forestry huts, weekend homes and canopies; nor is it allowed in trailers or vehicles that carry dangerous goods. |
| Vehicle size | Small and medium-sized. |
| Unit dimensions (L x W x H) | 510 x 450 x 300 mm |
| Minimum installation dimensions | 540 x 500 x 350 mm, with additional space for the gas connection, the water connections and the drain valve depending on the installation situation. |
| 12 V supply | The unit runs on 12 V; you will find the consumption in the technical specifications. |
| Controls and accessories | Only with the matching Truma control panels and accessories. The vehicle manufacturer decides where the room temperature sensor goes. |
In short, the type of vehicle and the free space are the first things to confirm. If anything does not match your situation, ask your installer before you buy.
Gas, regulator and driving
Truma is very specific about gas, because the supply pressure must match the unit's and, if you want to heat on the road, you need a safety shut-off device. The MonoControl CS regulator meets that requirement, and for two-cylinder installations Truma recommends the DuoControl CS vertical or the DuoControl CS horizontal.
| Topic | What Truma says |
| Gas and pressure | LPG (propane / butane) at 30 mbar. The service pressure of the supply and that of the unit (rating plate) must match. |
| Regulator | Regulating devices to DIN EN 16129 (in vehicles), with a fixed outlet pressure of 30 mbar and a flow rate that covers at least the maximum consumption of all appliances. Truma recommends the MonoControl CS and, with two cylinders, the DuoControl CS. |
| Cylinders | Upright, drawing gas in the vapour phase; you must not draw it in the liquid phase. |
| Cold | At temperatures around 0 °C or below, the regulator or the changeover valve must work with the EisEx regulator heater. |
| While driving | Safety shut-off device in accordance with UNECE Regulation 122, e.g. the MonoControl CS. Without it, you keep the cylinder closed and put up warning signs in the gas locker and near the control panel. |
| When not to use it | Never during refuelling, in car parks, garages or on ferries: switch it off at the control panel, and it must not be possible to switch it on remotely. |
So, if you want heating while you drive, the safety shut-off device (such as the one on the MonoControl CS) is not optional. The conditions for the cowl, the water and the warm-air ducts are further down, in the installation section.
Technical specifications of the Truma Combi 4 gas heater
For reference, these are the official figures for the Truma Combi 4 gas heater according to Truma's manual. The dimensions, the gas and the service pressure are already in the compatibility table, because they affect the installation.
| Specification | Value |
| Water capacity | 10 litres (stainless steel tank) |
| Water heating time from approx. 15 °C to approx. 60 °C | water heater only: approx. 23 min (EN 15033); heating + water heater: approx. 80 min |
| Pump pressure / system pressure | max. 2.8 bar / max. 4.5 bar |
| Air flow (free-blowing, without ducting) | max. 249 m³/h with 3 outlets; max. 287 m³/h with 4 outlets |
| Standby heat consumption | 8.6 g/h in gas operation (EN 15033) |
| Quiescent current at 12 V | approx. 0.001 A |
| Heating the water only, at 12 V | max. 0.5 A |
| FrostControl heating element (optional) at 12 V | max. 0.4 A |
| Protection type | IPX1 |
| 12 V fuse | 10 A fast-acting, 5 x 20 mm |
| Rated heat output (automatic stages) | 2000 W / 4000 W |
| Gas consumption | 160 – 335 g/h |
| Data according to EN 624 | Qn = 4.8 kW (Hs), 345 g/h, C13, I3 B/P(30) |
| Consumption at 12 V, heating + water heater | 1.2 – 6.5 A |
| Weight without water | 14.4 kg (with peripherals: 14.9 kg) |
At 14.4 kg without water, the Truma Combi 4 gas heater weighs the same as the Combi 6, even though the latter reaches a higher output. In the weight with peripherals, Truma counts the control panel, the FrostControl, the bracket, the flexible hoses, the cables and the fixing material, but not all of these come in the box.
How the Truma Combi 4 gas heater works
It is a blown air heater with a built-in water heater. When it is cold, the Truma Combi 4 gas heater warms the living area and heats the water at the same time. In summer you can select hot water only, and the burner then heats the tank on its lowest stage until the water reaches the desired temperature, at which point the burner switches off.
When it works as a heater, the unit chooses the output stage by itself according to the difference between the temperature set on the control panel and the ambient temperature. While a room temperature sensor measures the air in the vehicle, other internal sensors monitor the water. Before it reaches the set value it reduces the output and, when the temperature drops, it switches on again without you doing anything.
Inside, the combustion air enters through the outer duct of the cowl and a fan carries it to the burner, which has two ignition electrodes and one flame-sensing electrode and ignites the mixture of gas and air. A circulation fan then blows the air over the fins of the heat exchanger and distributes it through four outlets.
The stainless steel tank is eccentric in shape. According to Truma, this makes the hot water circulate and mix better and gives it better thermal stratification, and the HDF thermal cover insulates the unit.
With an empty tank and while driving
An empty tank is not a problem, because the Combi 4 can work as a heater only. While you drive, the fan-assisted burner keeps running, but it requires the safety shut-off device mentioned above, such as the MonoControl CS.
iNet X Panel control panel for the Truma Combi 4 gas heater
This version comes with the iNet X Panel, Truma's central operating system, so you do not have to choose another control panel. With its 4.3-inch touchscreen you control the heating, the air-conditioning system and the Truma LevelControl, and you can also do so from the free iNet X App over Bluetooth.
| Specification | Value |
| Display | TFT-LCD 4.3" touchscreen (resistive) |
| Power supply | 12 V (8 V – 16 V) |
| Consumption | 1.5 W |
| Interfaces | TIN bus, CI bus, CAN bus and Bluetooth Low Energy (BLE) |
| Operating and storage temperature | -30 °C to 60 °C |
| Battery | CR 2032, lasts approximately 8 years |
| Weight | approx. 150 g |
| Dimensions (L x W x H) | 96.7 x 120.1 x 31 mm |
| Protection | class III; front IP20, rear IP00 |
| Physical buttons | Home and Back |
| Phones connected at once (iNet X App over Bluetooth) | up to 3 |
| Timers | up to 6 (set in the app) |
| Appliances it controls | heating, air-conditioning system and Truma LevelControl |
| Remote control | with the iNet X Connect module (optional, not included) |
| Manufacturer's warranty | 24 months |
The panel thus shows the indoor climate and the outdoor and indoor temperatures, and displays specific error messages with solutions. With the Truma LevelControl, which you buy separately, you can also see the gas fill level.
App, updates and everyday use
You can also download the app from Google Play (Android) or the App Store (iOS), depending on your operating system. You install software updates from your phone, with an internet connection and Bluetooth, and they can take up to 15 minutes; if they fail, the panel reverts to the last software installed.
If you do not touch it for 60 seconds, the screen goes to the lock menu and, after another 60 seconds, to standby mode. Even so, the paired phones can still control the connected appliances. To clean the screen, use a non-abrasive cloth dampened with water or, if that is not enough, a mild soap solution.
Installation and fitting of the Truma Combi 4 gas heater
As Truma requires, only qualified and authorised personnel (technicians) may fit, repair and inspect the Truma Combi 4 gas heater. They must also follow the installation and operating instructions and the technical standards in force. This is not a job to do yourself, so plan the installation at the same time as you choose the unit.
| Item | What the installer must allow for |
| Cowl | Do not block it, and Truma prohibits fitting covers over the cowl. When cleaning the vehicle, do not spray water directly at it. The unit needs an exhaust system, which is not in the box. |
| Opening window | If the cowl is near or below a window that opens, you need an automatic cut-off device; under EN 1949, a window switch if it is less than 30 cm away. |
| Warm-air ducts | Truma does not allow the unit to run without them. |
| Mains water | If you connect the vehicle to a mains water supply (external pressure), a pressure-reducing valve so that the water heater does not have to withstand more than 2.8 bar. |
| Solar installation | Under EN 1648, always a battery with a charge controller or a voltage regulator (11 V – 15 V; AC voltage ripple < 1.2 Vpp) between the panels and the heater. |
| Yellow label | The installer or the owner must stick the enclosed warning label in a place clearly visible to all users, e.g. the wardrobe door. |
As you can see, the list covers the exhaust, the water and the electrics, so it is worth having the installer go through all of it before fitting.
Water, FrostControl and frost
Because the Combi has no built-in frost protection, frozen water can seriously damage the unit. That is why Truma offers the FrostControl valve, which comes inside the FC TB (36100-01) or FC JG (36100-02) water connection set; that set is not in the box.
It is a safety and drain valve that needs no electricity. If frost threatens, it drains the water heater through a drain pipe and opens by itself below about 3 °C. You can only close it by hand when the valve is at about 7 °C or more. If you leave the vehicle unused in frosty weather, always drain the water heater, because Truma excludes frost damage from the warranty.
What the box contains and the accessories you need
The version with the iNet X Panel (Truma 33704-20) comes with the following in the box, according to the contents published by Truma:
- Heater with room temperature sensor.
- iNet X Panel control panel.
- 6 m control panel cable.
- Fixing parts.
The following, however, is not in the box, so you need to allow for it before you arrange the installation. The contents do not list the warm-air ducts either, although the unit cannot run without them.
- Exhaust system: ZR 80 wall cowl or roof cowl, with exhaust pipe and combustion air pipe.
- FC TB (36100-01) or FC JG (36100-02) water connection set, which includes the FrostControl valve and the elbows.
- FrostControl safety and drain valve, which comes inside that set, and the optional heating element (70070-01), which you buy separately.
- iNet X Connect remote module, which is optional.
- Warm-air ducts and outlets.
- Gas pressure regulator, such as the MonoControl CS or the DuoControl CS.
Official Truma part numbers for the exhaust
For the exhaust, Truma publishes these part numbers, which serve as a guide when ordering the material from your installer; none of them comes with this heater.
| Part number | What it is | What it is for |
| 36240-01 | Complete ZR 80 wall cowl kit: inner cowl part, 1.1 m exhaust pipe, 1 m combustion air pipe and clamps (without the outer cowl part) | Routing the exhaust gases out through the vehicle wall |
| 34122-01 | Complete CD roof cowl kit: 3 m AA 3 exhaust pipe, 3 m ZR 80 combustion air pipe and clamps | Routing the exhaust gases out through the roof |
| 36140-01, 36151-01 / -05 / -08 / -09 / -10, 34051-01, 39320-00, 39580-00, 39590-00, 34070-01, 34080-01 | Loose parts: ZR 80 inner part, outer parts in cream, bianco, light grey, black and anthracite, DKC 2 roof cowl, pipes by the metre, clamp, 30 cm extension and SDDF wall bushing | Completing or extending the wall or roof cowl |
Official Truma part numbers for water, air and other accessories
For water, warm air and window cut-off, Truma also publishes the following part numbers.
| Part number | What it is | What it is for |
| 36100-01 | FC TB water connection set: FrostControl TB power-free drain valve, TB elbows for Ø 10 mm flexible water hoses and black PVC flexible hose (TB = barbed connection) | Connecting the water and draining the water heater if there is a risk of frost |
| 36100-02 | FC JG water connection set: FrostControl JG power-free drain valve, JG elbows for Ø 12 mm rigid pipe and transparent PVC flexible hose (JG = John Guest system) | The same as the one above, with rigid pipe |
| 70070-01 | FrostControl heating element with 1.5 m cable | Filling the water tank sooner, regardless of the ambient temperature |
| 34092-01 / 34310-01 | Black BGC elbow for connecting warm-air ducts (Ø 65 mm or Ø 72 mm) directly and black CB blanking cap | Connecting or closing off a warm-air outlet |
| 34030-34700 / 34020-01581 | Window switch for standard caravan opening windows, and narrow window switch | Switching the heater off when you open the window |
| 47000-00140 | Alternative iNet X room temperature sensor (e.g. FFC2), for direct connection to the Truma iNet X Panel control panel | Alternative sensor that connects directly to the control panel |
Control panel cables are also available in various lengths, up to a maximum of 10 m. The window switch is mandatory if the cowl is below an opening window or less than 30 cm from it.
Who is the Truma Combi 4 gas heater for?
The Truma Combi 4 gas heater suits you if you want heat and hot water in a small or medium-sized vehicle and prefer gas. For example, if any of these sounds like you:
- You travel in a small or medium-sized motorhome or caravan and want to avoid two separate appliances.
- You are fitting new equipment with your installer and want a heater that runs on gas only.
- You want heating on the road and are willing to install a regulator with a safety shut-off.
- You prefer to control the temperature from your phone, with up to 3 phones at once.
- In summer you only need hot water, without switching the heating on.
- Your campervan is approved as a motorhome (class M1); you cannot fit this unit in a commercial vehicle (class N).
Maintenance, cleaning and warranty for the Truma Combi 4 gas heater
To keep the Truma Combi 4 gas heater performing, have the unit's cleaning service carried out by specialist technicians and clean the installation space at least once a year. Also use the safety and drain valve regularly, at least twice a year, to remove limescale and check that it has not seized up. For safety, children must not carry out maintenance or cleaning.
You must also sterilise and descale the water tank regularly. Cleaning products sold in camping shops are suitable and, to remove limescale, so are commercial descalers, vinegar essence or citric acid. Pour them in through the water inlet in the recommended proportion, leave them to work and rinse thoroughly with clean water.
To combat micro-organisms, Truma adds a complementary method: when the water reaches 60 °C the burner switches off, you keep the unit switched on for at least another 30 minutes and you do not draw any hot water, so that the residual heat takes it up to 70 °C.
Fuse, solar installation and smell of gas
Before opening the connection cover, disconnect the 12 V on all poles. Also, before touching the electronics you must establish equipotential bonding, because electrostatic charge can damage them beyond repair. Replace the fuse only with one of the same type, and then put the cover back.
With solar panels, when disconnecting the battery, disconnect the charge controller first and, when reconnecting, connect it last.
If you smell gas, Truma says to avoid any source of ignition, open windows and doors, evacuate the vehicle, close the gas cylinders and have the installation checked by technicians before using it again.
Manufacturer's warranty
Truma offers a voluntary 24-month warranty against material or manufacturing defects, valid in the member states of the European Union, Iceland, Norway, Switzerland and Turkey. If there is a covered defect, the manufacturer or an authorised Service Partner repairs or replaces the unit. It is the manufacturer's warranty, it does not replace the statutory warranty and it excludes frost damage.
Frequently asked questions
What is a Truma Combi boiler and what does the Truma Combi 4 gas heater do?
A Truma Combi boiler is a blown air heater with a built-in water heater. The Truma Combi 4 gas heater warms the living space and heats the 10 litres in its stainless steel tank with a single gas appliance, so you do not need a separate water heater.
Can I use the Truma Combi 4 gas heater while driving?
Yes, but only if the installation has a safety shut-off device in accordance with UNECE Regulation 122, such as the MonoControl CS regulator. If it does not, you must keep the gas cylinder closed while driving and put warning signs in the gas locker and near the control panel.
Is the Truma Combi 4 gas heater suitable for my campervan?
Yes, as long as the van is approved as a motorhome (vehicle class M1) and the gas installation complies with EN 1949. Truma also does not allow fitting it in commercial vehicles (class N). Truma designed this Combi for small and medium-sized vehicles, while the Combi 6 is for large ones.
Combi 4 or Combi 6: which one do I need?
It depends on the size of the vehicle, because Truma sorts the Combi range into small, medium and large. While the Combi 4, at 2000 W and 4000 W, is for small and medium-sized vehicles, the Combi 6 reaches 6000 W and is for large vehicles. Both weigh 14.4 kg without water.
What else do I need to buy to install it?
The box does not include the exhaust system or the water connection set with the FrostControl. It does not include the warm-air ducts either, which the unit needs to work. You also need a gas regulator, such as the MonoControl CS, and a qualified installer, because Truma only allows fitting by technicians.
