RV & Camper Diesel Heater — Air & Water Models for Every RV Type
A diesel heater is the most practical way to stay warm off-grid in cold weather. It works the same in a camper van, a caravan, or a full-size motorhome. It runs on the diesel you already carry, heats down to -40°F (-40°C), and works parked or driving.
Vvkb builds two kinds. Diesel air heaters blow warm air straight into your living space; the diesel water heater feeds your coolant loop for hydronic systems. Both burn fuel in a sealed chamber, so your cabin air never touches the combustion process.
Every part is picked for cold-weather duty. The housing is glass-fiber reinforced plastic with A380 die-cast aluminum components. The heat exchanger is cast under 1,000 tons of pressure, so the walls come out dense and free of pinholes. The Japanese Kyocera ceramic glow plug lights the fuel at -40°F (-40°C).
Why RV Owners Choose Vvkb
You are buying from the factory that makes the heater, not from a reseller who buys whichever unit is cheapest that quarter. Vvkb has manufactured vehicle heaters since 1996 and started building diesel heaters in 2003.
- Rated to -40°F (-40°C) — the Kyocera ceramic glow plug lights in temperatures where cheap plugs stop firing
- 0.136–0.252 L/hr on the Apollo-V1 — about 1 to 1.5 liters for an eight-hour night on low
- 1.46–2.2A running draw at 12V — light enough that a healthy leisure battery runs it all night
- ~50dB on the Apollo-V1 at low — quieter than normal conversation, measured rather than claimed
- Sealed combustion chamber — intake and exhaust both route outside, so exhaust never enters your living space
- 2.1kg die-cast heat exchanger — the same part weighs 1.56kg on budget units, and that difference is wall thickness
- Certification records you can check — the Apollo-V1 carries ECE R122 and R10 type approval. Every model has CE, RoHS and FCC documentation on file. See the certification records for the numbers
What Is an RV Diesel Heater?
An RV diesel heater is a self-contained furnace that burns diesel to heat your living space without running the engine. You get heat parked overnight, camping off-grid, or driving through sub-zero weather.
Unlike a propane furnace, it draws from the fuel tank already under your vehicle. There are no bottles to swap, no refill stops mid-trip, and no propane locker to find space for.
| Diesel Air Heater | Diesel Water Heater | |
|---|---|---|
| How it heats | Blows warm air directly into the cabin | Heats coolant, which feeds radiators or underfloor loops |
| Best for | Vans, campers, small to mid-size RVs | Large motorhomes and boats with hydronic systems |
| Installation | Two holes, one fuel tap, 12V feed — most owners do it themselves | Multiple components, coolant plumbing — professional fit recommended |
| Vvkb models | Apollo-V1 (2.5KW), Apollo-V2 (5KW) | Apollo-C1 (5KW) |
If you are heating one open space, the diesel air heater is the straightforward answer. If your motorhome already has a hydronic loop, the Apollo-C1 ties into the coolant circuit you have.
What It Costs to Run Compared With a Propane Furnace
Diesel delivers roughly 2.4 times more usable heat per dollar than propane in an RV. The gap comes from combustion efficiency, not from the pump price of the fuel.
A typical RV propane furnace sends 40–42% of its heat straight out the exhaust, leaving about 58–60% inside. A diesel air heater runs near 90%, because the fan pulls heat off the exchanger before the gases leave. Diesel also carries more energy per gallon to begin with — 139,000 BTU against 92,000 BTU for propane.
| Diesel air heater | RV propane furnace | |
|---|---|---|
| Energy per gallon | 139,000 BTU | 92,000 BTU |
| Delivered to the cabin | ~90% | ~58–60% |
| Usable BTU per gallon | ~125,000 | ~54,000 |
| Cost per 100,000 usable BTU | ~$3.04 at $3.80/gal | ~$7.37 at $4.00/gal |
| Overnight, 8 hours | $1.10–$2.40 | $6–$8 |
Fuel prices move, so treat the dollar figures as a worked example rather than a quote. The ratio between the two is what stays stable, because it is set by physics rather than by the market.
There is a second cost most buyers miss. Burning propane releases water vapor into your living space, which is why propane-heated campers wake up with wet windows and damp bedding. Diesel combustion happens inside a sealed chamber vented outdoors, so the heat you get is dry.
Will a Diesel Heater Drain Your Leisure Battery?
No — a diesel air heater draws 1.46 to 2.2 amps at 12V once running, which is less than most LED lighting circuits. Over an eight-hour night that is roughly 12–18Ah, well inside a single 100Ah battery.
The moment that matters is start-up. The glow plug pulls around 8 amps for two to three minutes while it heats enough to light the fuel. That spike is what your battery has to cover.
| Phase | Apollo-V1 (2.5KW) | Apollo-V2 (5KW) |
|---|---|---|
| Glow plug start-up, 2–3 min | ~8A | ~8A |
| Running, high | 1.46A | 1.93A |
| Running, boost | 1.68A | 2.2A |
| Eight-hour night, low to medium | ~10–13Ah | ~13–18Ah |
Failed ignition on a cold morning is almost always a voltage problem, not a heater fault. If the pack sags below about 11.5V during the start sequence, the plug never gets hot enough. The unit reports a fault code instead of lighting.
Two things prevent it. Run the heater from the leisure battery on its own fused feed, not a shared accessory circuit. Keep the supplied 4-meter cable rather than extending it with thinner wire. If you are still on aging lead-acid, a lithium pack holds voltage far better through the spike.
Is an RV Diesel Heater Safe to Sleep With?
Yes, because the combustion side and the air you breathe are physically separate circuits. Outside air enters a sealed chamber through its own intake, and exhaust leaves through its own pipe — both routed outside your RV.
Cabin air is blown across the outside of the heat exchanger and back into the room. It picks up heat through the exchanger wall, and never enters the chamber where the fuel burns. That wall is the barrier, which is why its casting quality matters more than any other part.
The Apollo series adds an overheat sensor that shuts the unit down automatically if temperatures pass design limits. For the full explanation of how sealed combustion works and what the standards require, read whether a diesel heater is safe to sleep with.
One habit is worth keeping regardless: fit a carbon monoxide detector in any space you sleep in. It costs very little. It also covers the one thing engineering cannot — a joint that shakes loose on a rough road.
How an RV Diesel Heater Works
The heater runs a six-stage cycle every time you switch it on, and it takes three to five minutes from button press to warm air. Understanding the sequence makes fault codes far easier to read.
- Air intake — outside air is drawn into the sealed combustion chamber through its own pipe
- Fuel metering — the pump delivers diesel in measured pulses, 0.136 to 0.475 L/hr depending on model and heat level
- Ignition — the Kyocera ceramic glow plug lights the fuel-air mixture, drawing about 8A for two to three minutes
- Heat exchange — combustion heats the die-cast aluminum exchanger from inside
- Air circulation — the blower pushes cabin air across the outside of the exchanger and back into your space
- Exhaust — combustion gases leave through a separate pipe to the outside, never entering the cabin
Once it reaches your set temperature the heater modulates fuel delivery rather than cycling on and off. That is why a diesel unit holds a steadier temperature than a propane furnace that switches between full output and nothing.
Every start begins with a self-check on the pump, plug, sensors and blower. If something is wrong the control panel shows a code instead of running blind — the full list is in the diesel heater troubleshooting guide.
Vvkb RV Diesel Heater Models
Three models cover everything from a converted panel van to a 40-foot motorhome. Pick by heated volume first and by heating method second.
Apollo-V1 — 2.5KW Diesel Air Heater
Built for camper vans, small caravans and spaces up to about 20m².
- 2.5KW / 8,500 BTU at boost, five heat levels
- Rated to -40°F (-40°C), normal operation to 11,483 ft (3,500 m)
- 0.136–0.252 L/hr fuel use, 1.46–1.68A at 12V
- ~50dB at low setting
- 310 × 122 × 115mm, 2.6kg (5.7 lbs)
- Kyocera ceramic glow plug, 24mm exhaust, 4-meter flame-retardant harness
- ECE R122 and R10 type approval (E-mark), plus CE, RoHS and FCC
Apollo-V2 — 5KW Diesel Air Heater
Built for large motorhomes, buses and spaces over about 20m².
- 5KW rated — 4.7KW / 16,100 BTU measured at boost
- Rated to -40°F (-40°C)
- Five heat levels plus a 99-hour programmable timer
- 2520 stainless steel combustion chamber, holds shape at 1,200°C
- 0.201–0.475 L/hr fuel use, 1.93–2.2A at 12V
- 380 × 140 × 138mm, 4.8kg
- CE, RoHS and FCC documentation
Apollo-C1 — 5KW Diesel Water Heater
Built for large motorhomes, boats and any RV with an existing hydronic loop.
- 5KW output, heats coolant to 60–80°C
- Rated to -49°F (-45°C)
- German circulation pump
- Kyocera ceramic glow plug
- Heats your living space and pre-warms the engine from the same unit
- CE, RoHS and FCC documentation
What to Look for When Buying an RV Diesel Heater
1. Ask for the certification numbers, not the logos
Anyone can print a CE logo on a box, because CE is a manufacturer self-declaration rather than an independent test. Type approval — the E-mark — is different. It is issued by a national authority, it carries a traceable number, and anyone can look it up.
The Apollo-V1 holds ECE R122 approval E24*122R00/06*0054*00 and ECE R10 approval E24*10R06/02*4825*00, both issued through NSAI in Ireland. Every Vvkb model has CE, RoHS and FCC documentation on file, and you can see the whole set on the certifications page.
The test to apply to any seller is simple. Ask which authority issued the approval and what the number is — a factory answers in one message, a rebadger goes quiet.
2. Heat output: 2.5KW or 5KW?
- Camper van or small caravan under ~20m² → Apollo-V1, 2.5KW / 8,500 BTU
- Large RV or motorhome over ~20m² → Apollo-V2, 5KW / 16,100 BTU
- Multiple zones or an existing hydronic loop → Apollo-C1 water heater
When you are between sizes, go up. A 5KW unit running at low output is quieter, cleaner and less prone to soot than a 2.5KW unit held at full throttle all night.
3. Heat exchanger weight
The exchanger wall is the only thing between exhaust gas and the air you breathe. Its casting quality is a safety spec, not a performance one. A Vvkb 5KW exchanger weighs 2.1kg in ADC12 alloy; the equivalent budget part weighs about 1.56kg.
That 0.5kg is wall thickness and casting density. Thin, porous castings develop pinholes as sulfuric residue attacks the aluminum. A pinhole in that wall is the one failure that puts exhaust into your living space.
4. Cold start reliability
At -22°F (-30°C) the glow plug decides whether you get heat at all. Kyocera ceramic plugs reach ignition temperature faster than the metal-sheathed plugs fitted to budget units and last considerably longer in service.
Plugs are consumables on every brand — expect two to three years of regular use. The difference is that a replacement Kyocera plug is a stocked part rather than a hunt through marketplace listings.
5. Altitude rating
Thin air changes the air-fuel ratio, and a heater that cannot compensate sooties up its own burner. Vvkb controllers use a barometric sensor and adjust the mixture automatically for normal operation up to 11,483 ft (3,500 m).
Camp higher than that regularly and the fuel curve can be recalibrated at the factory, for operation to 18,045 ft (5,500 m). That is a build-time option rather than a setting, so specify it when ordering. Details are in the high altitude diesel heater guide.
The Downsides Nobody Puts in the Ad
A diesel heater is the right answer for most RVs, but it is not free of trade-offs. Here is the honest list, because knowing them up front is what keeps a heater working for ten years.
- You have to drill. Two holes through the floor or wall for exhaust and intake. There is no version of this that clamps on.
- The fuel pump ticks. A metering pump makes an audible click on every pulse. Mounting it on the supplied rubber bracket at a 15–30° angle, away from the sleeping area, takes care of most of it.
- Running on low forever causes soot. Long, low-output sessions are the single biggest cause of carbon build-up. Run it hot for an hour, then off, rather than simmering all night at minimum.
- It needs servicing. Plan on opening the combustion chamber roughly once a year for heavy users — clean the screen, scrape the carbon, check the plug. A neglected burner throws fault codes in the middle of winter.
- Never kill the power while it is running. Cutting the supply skips the cooldown cycle, leaving unburnt fuel to coke inside a hot chamber. Always shut down from the control panel and let the fan finish.
- Cold-weather diesel matters. Untreated summer diesel can gel below about 5°F (-15°C) and starve the pump. Winter-blend fuel or an anti-gel additive solves it.
RV Diesel Heater for Every Vehicle Type
Fit depends on heated volume and where you can route two pipes. These are the five setups we get asked about most.
Camper Van
Under 10m² in most builds. The 2.6kg Apollo-V1 fits under a seat or in a cabinet base, with both pipes through the floor.
Caravan & Travel Trailer
15–25m². The Apollo-V1 suits smaller vans; larger twin-axle caravans want the Apollo-V2 with a dedicated tank.
Campervan Conversion
The 310 × 122 × 115mm footprint fits the void under a fixed bed. It runs with the engine off, so you stay warm without idling.
Van & Overlanding
Panel vans and expedition builds where cargo space is the constraint. Ducting lets you put the heater out of the way and the outlet where you sleep.
Motorhome
Larger volumes need the Apollo-V2. Where a hydronic loop already exists, the Apollo-C1 feeds radiators and underfloor from the same burner.
Boat & Marine
Both air and water models work afloat with the marine kit. The Apollo-C1 suits cabins that already have a calorifier.
How to Install an RV Diesel Heater
Most owners with basic mechanical skills fit an air heater in a day. The work is five steps, and everything except the fuel tap is in the box.
- Mount the heater — under a seat, in a cabinet or under the floor, on the supplied plate. Keep at least 8 in (20 cm) of clear space around the combustion air intake, or you will chase E03 overheat codes later
- Drill for exhaust and intake — two holes through floor or wall. The exhaust must point downward or rearward and must never sit near a window, vent or air intake
- Run the fuel line — tap the existing diesel tank with the supplied standpipe, or fit a small auxiliary tank. Mount the pump below tank level, tilted 15–30° with the outlet up
- Connect 12V — the 4-meter harness runs to a fused feed at the leisure battery. Do not extend it with thinner cable
- Run the self-check — power up and let the startup sequence complete before your first trip. First light produces some white smoke while the fuel line purges, which is normal
For a step-by-step walkthrough with tools and torque figures, follow the complete diesel heater installation guide. For the Apollo-C1 and any coolant plumbing, use a workshop — a hydronic loop with air trapped in it will not circulate.
Diesel heaters work in petrol RVs too. You add a small auxiliary diesel tank, and the heater runs entirely independently of the engine and its fuel.
Frequently Asked Questions
Are diesel heaters good for RVs?
Yes, and for off-grid use they are the strongest option available. They run from the fuel you already carry, draw 1.46–2.2A at 12V, and produce dry heat. They also hold a steadier temperature, because they modulate output instead of cycling on and off. The trade-offs are an installation that requires drilling and a burner that needs cleaning about once a year.
Is a diesel heater cheaper to run than an RV propane furnace?
Yes, by roughly 2.4 times per unit of usable heat. Diesel carries 139,000 BTU per gallon against 92,000 for propane. A diesel air heater delivers about 90% of that into the cabin; an RV propane furnace delivers 58–60%. An eight-hour night costs about $1.10–$2.40 in diesel against $6–$8 in propane.
Will a diesel heater drain my leisure battery overnight?
No. Running draw is 1.46–2.2A at 12V, so an eight-hour night uses roughly 12–18Ah from a 100Ah battery. The load that matters is the glow plug at start-up, which pulls about 8A for two to three minutes. If your pack sags below 11.5V during that window, ignition fails. Give the heater its own fused feed and keep the supplied 4-meter cable.
What are the disadvantages of a diesel heater?
Four, honestly. You have to drill two holes for the exhaust and intake. The metering pump ticks unless it is rubber-mounted away from the bed. Long runs at minimum output cause carbon build-up, so it is better to run hot then switch off. And the burner needs cleaning roughly once a year in heavy use. None of these are brand-specific — they are how the technology works.
Can I run a diesel heater while driving?
Yes. The Apollo-V1 holds ECE R122 and R10 type approval — the E-mark — which is the European standard covering combustion heaters used in moving vehicles. The sealed combustion system behaves the same parked or under way, and the exhaust exits outside the vehicle either way.
Do I need a carbon monoxide detector with a diesel heater?
The heater does not require one, but you should fit one anyway. Sealed combustion means exhaust cannot reach cabin air during normal operation. What a detector covers is abnormal operation — an exhaust joint shaken loose on a rough track. A detector costs a fraction of one night's fuel.
Can I duct a diesel heater into my existing RV furnace vents?
Sometimes, but check the duct diameter first. Vvkb air heaters use 60mm outlets on the Apollo-V1 and 75mm on the Apollo-V2. Most factory RV ducting is 4 inches or larger, so you need an adapter and short runs. Long, wide ducting drops outlet temperature sharply, so a short dedicated duct usually beats reusing the furnace trunking.
Will diesel fuel gel in extreme cold?
Untreated summer-blend diesel can begin to gel around 5°F (-15°C), which starves the pump long before the heater itself reaches its limit. Winter-blend fuel from any northern filling station is treated for local conditions, and an anti-gel additive covers you if you drove north on southern fuel. The heater itself is rated to -40°F (-40°C).
Does a diesel heater work at high altitude?
Vvkb heaters compensate automatically for normal operation up to 11,483 ft (3,500 m) using a barometric sensor that adjusts the air-fuel ratio. Above that, thin air causes incomplete combustion, reduced output and faster soot build-up. For regular camping higher than 11,483 ft, the fuel curve can be recalibrated at the factory before shipping for operation to 18,045 ft (5,500 m).
Can a diesel heater work in a gas or petrol RV?
Yes. You fit a small auxiliary diesel tank, typically 5 to 10 liters. That is several nights of heat, and the heater runs completely independently of your engine and its fuel. All it needs from the vehicle is a 12V feed.
Talk to the People Who Build It
Vvkb has manufactured vehicle heaters since 1996 and diesel heaters since 2003, from our own factory rather than a trading office. Ask for a certification number, a spare glow plug or a fuel curve recalibration. You get an answer from someone who has the drawing.
Retail buyers get stocked units with regional shipping through rvheater.com. Converters, rental fleets and dealers should contact us directly for volume pricing and OEM options.