Diesel Heater Size Calculator (2–5 kW)
Pick the right diesel heater size for your van from 2–5 kW using volume, insulation, and climate. Clear verdict plus heat-load estimate.
How do I estimate my van’s interior volume (m³)?
Measure interior **length × width × average height** after furniture. Example: 3.2 m × 1.7 m × 2.0 m ≈ **10.9 m³**. Use a preset if you’re close; exact decimals aren’t needed.
Which insulation option should I pick?
Be conservative. Most DIY builds are **“decent”** (thermal bridges, windows). Pick **“good”** only if you’ve detailed bridges and glazing well; pick **“poor”** for minimal insulation.
Nights vs full-day — why does it change the result?
Full-day winter use adds runtime and recovery needs (doors opening, cold starts). The tool adds a buffer so the heater isn’t maxed out all day.
I’m between 3 kW and 4–5 kW — what now?
If you camp in **real cold**, work inside, or have lots of glass, go up a size and ensure you can run **hot burns** regularly. If you mostly do shoulder seasons, the smaller unit may be nicer (quieter, less idling).
Does altitude affect this sizing?
Yes. Higher altitude reduces oxygen and heater output. If you spend time above ~1,500–2,000 m, treat results as **optimistic** and consider the next size up or an altitude kit.