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Updated Apr 21, 2026Fact-checked on Apr 21, 2026
Hot water is the comfort upgrade that changes van life — but the power implications vary wildly between a propane instant heater, a 12V electric heater, and a DIY solar shower. What actually makes sense?
A propane instant heater (Camplux, Joolca) uses almost no battery — just a few watts for the igniter and fan. An electric 12V inline heater draws 10-20A continuously and only produces lukewarm water. The most efficient setup for most vans is a diesel-fired water heater (like the Webasto dual-top) that taps into your existing diesel heater circuit.
Expert tip
The best hot water setup for full-time van life is a combination: propane tankless for daily showers, plus a 12V immersion heater for quick hand-washing. Total power cost: under 20Wh/day. Total hardware cost: under €150. Maximum comfort, minimum electrical complexity.
Example calculation for your setup
Results based on a typical use case
| Appliance | Power | Usage/day | Wh/day |
|---|---|---|---|
| Compression fridge | 45W | 24h | 1080 |
| LED lighting | 20W | 4h | 80 |
| Water pump | 30W | 0.5h | 15 |
| Phone charging | 15W | 2h | 30 |
| Daily consumption | 1205 Wh | ||
Recommended LiFePO4 battery
151 Ah
(80% depth of discharge)
Recommended AGM battery
241 Ah
(50% depth of discharge)
Recommended solar panels
402 Wc
VANPOWERCALC.COMYOUR ENERGY PROFILE
YOUR ENERGY PROFILE.
This document contains the sizing of your future electrical installation, calculated based on your appliances.
Minimum Daily Consumption
0 WH / DAY
Inventory:
SYSTEM SIZINGPage 2
Battery
To guarantee 0WH without damaging your bank (80% max discharge):
0 AH
LiFePO4 12V
Solar
Minimum power required to recharge your consumption:
0 W
via MPPT
220V AC
Maximum power (with 25% safety margin).
0 W
No Need
Safety & CablingPage 3
12V Cable Sizing Guide
Use this professional reference table to select the correct gauge (mm²) for your cables. For 12V in a van, the maximum tolerated voltage drop is 3%. Always use multi-stranded flexible automotive wire.
| Current (A) | Round trip < 2m | Round trip 4m | Round trip 6m |
|---|---|---|---|
| 5A (LEDs, USB) | 1.5 mm² | 2.5 mm² | 4 mm² |
| 10A (Fridge, Pump) | 2.5 mm² | 4 mm² | 6 mm² |
| 20A (Heater) | 4 mm² | 10 mm² | 10 mm² |
| 50A (DC/DC Booster) | 10 mm² | 16 mm² | 25 mm² |
| 100A (Inverter) | 25 mm² | 35 mm² | 50 mm² |
Fuse Sizing
The fuse protects the wire, not the appliance. Always place it as close to the power source as possible (battery or busbar).
- Wire 1.5 mm² → Max fuse 10A
- Wire 2.5 mm² → Max fuse 20A
- Wire 4 mm² → Max fuse 30A
- Wire 6 mm² → Max fuse 40A
- Wire 10 mm² → Max fuse 60A
SCHÉMA ÉLECTRIQUE
PANNEAUX SOLAIRES
0W
RÉGULATEUR MPPT
BATTERIE AUXILIAIRE
0 Ah
Lithium LiFePO4
FUSIBLE
FUSIBLE
BOÎTE À FUSIBLES 12V
Pompe, Leds, Frigo...
CONVERTISSEUR 220V
NON REQUI
PRO GEARPage 4
SHOPPING LIST
Where to find this equipment? Here is the community-approved selection.
12V 6-way Fuse Box
Mandatory protection
Digital Multimeter
Test your connections
Heavy Duty Crimping Tool
For perfect lugs
Heat Shrink Tubing
Insulation and safety
GENERATED BY VANPOWERCALC.COM
Comparison table
| Option | Liters/use | Electric draw | Cost approx. |
|---|---|---|---|
| Outdoor shower (drum) | 5-10L | Pump 30W → 0.2Ah | $0/shower |
| 12V electric heater | 10L | 180W × 30min = 90Wh | $80-150 |
| Gas heater | 10L | Pump only ~2Wh | $60-120 + gas |
| Solar camp shower | 6-10L | Pump only ~2Wh | $20-40 |
| Diesel boiler | 10L | ~30Wh pump | $400-800 |
About this tool
Hot Water in a Van: Comparing Electrical and Non-Electrical Options#
Having hot water in a van is a game-changer for comfort — but the power implications vary wildly between systems. This guide covers the real electrical cost of each option so you can make the right choice for your build.
Hot Water Options Compared#
| System | Power Required | Hot Water Time | Best For |
|---|---|---|---|
| Propane tankless (Camplux 5L) | 0W (gas only) | Instant | Off-grid freedom |
| 12V DC immersion heater | 100-150W | 20-40 min (10L) | Simple solar builds |
| Diesel heater with hot water | 10-30W (fan) | 30-45 min | Cold climates |
| Electric tankless (230V) | 2,000-3,500W | Instant | Shore power only |
| Solar thermal collector | 0W | 2-4h of sun | Summer use only |
| Heat exchanger (engine coolant) | 0W | While driving | Supplemental only |
12V Immersion Heaters: The Solar-Friendly Option#
A 12V immersion heater rated at 100-150W can heat 10L of water in 20-40 minutes — enough for a daily shower. For 30 minutes of heating: 120W × 0,5h = 60Wh = 5Ah. That's very manageable with 200W of solar.
Recommended setup: a 10-15L insulated tank with a 12V immersion element, gravity-fed from a roof tank. The water stays hot for hours if the tank is well-insulated (neoprene sleeve). Cost: 30-60€ for the immersion element, 40-80€ for the tank.
Propane Tankless Heaters: Zero Electrical Cost#
The Camplux 5L and similar propane tankless heaters are the king of off-grid hot water. Electrical consumption: near zero (just a piezo igniter). The trade-off is propane gas cost (one 3kg bottle lasts 4-8 weeks for a single person) and the regulatory complexity of propane in some countries.
A 5L/min unit at 6 kW heats cold water (15°C) to shower temperature (38°C) at 2,3L/min — comfortable for a shower. For a couple, upgrade to 8L/min.
Diesel Heater Integration: The Winter Choice#
Webasto and Espar diesel heaters can be fitted with a hot water heat exchanger circuit. The electrical consumption stays at just 10-30W (for the fan) while the diesel burner heats the water. This is the most power-efficient option for winter van life in cold climates.
A Webasto Thermo 90 can heat a 10L tank from 15°C to 60°C in 30-35 minutes while also heating your cabin — two birds with one stone.
230V Electric Tankless: Shore Power Only#
At 2,000-3,500W, a 230V electric tankless heater requires a large inverter (minimum 3,500W pure sine) and drains even 400Ah LiFePO4 batteries in under 90 minutes. Use this only if you spend most nights at campsites with shore power.
Expert tip: The best hot water setup for full-time van life is a combination: propane tankless for daily showers, plus a small 12V immersion heater for quick hand-washing or dishes. Total power cost: under 20Wh/day for the 12V element, zero for the propane unit. Total cost: under €150.
Frequently asked questions
What is the lowest-power hot water system for a van?▼
A propane tankless heater (Camplux, Eccotemp, etc.) uses near-zero electricity — just a piezo igniter. A 12V DC immersion heater is the best electric option at 100-150W, heating 10L in 20-40 minutes (60Wh total for a daily shower).
Can I have a hot shower in a van off-grid without solar?▼
Yes, with propane tankless heaters that use no electricity, or with a diesel heater hot water circuit that uses only 10-30W. A 12V immersion heater also works but needs at least 100-200W of solar or regular driving to replenish the ~60Wh used per shower.
How much power does a 12V van water heater use?▼
A 12V immersion heater uses 100-150W. For a 10L hot water tank heated from 15°C to 50°C: it takes about 25-35 minutes, consuming 40-80Wh total. Very manageable with any solar setup.
Is a diesel heater worth it for hot water in a van?▼
Yes for winter van life. A diesel heater with a hot water heat exchanger heats your tank while also heating the cabin — same diesel fuel, same electrical draw (10-30W for the fan). Very cost-effective vs a separate hot water system.
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