When you’re building out a van, choosing how to heat your “living room” is one of the most critical safety and comfort decisions you’ll make. Most van lifers find themselves choosing between Open Combustion (like a propane camp stove or a “Buddy” heater) and Closed Combustion (like a diesel or propane furnace mounted under the seat or chassis).

While open combustion heaters are cheap and portable, closed combustion is the gold standard for a reason. Here is why.

---

1. Safety: Keeping Exhaust Outside

The biggest difference lies in where the air comes from and where the “bad stuff” goes.

• Open Combustion: These heaters pull oxygen directly from inside your van and release exhaust (including Carbon Monoxide and Carbon Dioxide) back into your living space. This requires you to keep a window cracked, which often defeats the purpose of heating.
• Closed Combustion: These units use a “sealed” system. They pull fresh air for the flame from outside through an intake pipe and push all toxic exhaust fumes back outside through a tailpipe. The air you breathe never touches the flame.

---

2. The Moisture Factor (Goodbye, Condensation)

If you’ve ever woken up in a van with water dripping from the ceiling, your heater might be the culprit.

Burning fuel creates water vapor as a byproduct.

• Open heaters dump that moisture directly into your van. For every gallon of propane burned, you’re essentially throwing about a gallon of water into your air.
• Closed heaters vent all that moisture outside. Because they blow hot, dry air into the cabin, they actually help wick away existing moisture (as we discussed in our last post!), keeping your windows clear and your bedding dry.

---

3. Efficiency and Oxygen Levels

Because open combustion heaters consume the oxygen inside your van, they can eventually lead to oxygen depletion in a small, sealed space. Most modern portable heaters have an “Oxygen Depletion Sensor” (ODS) that shuts them off, but this means your heater might quit in the middle of a freezing night just because you’re breathing.

Closed combustion heaters don’t care how airtight your van is—they get their “breath” from the great outdoors, allowing you to stay sealed up, warm, and safe all night long.

---

Comparison at a Glance

Feature	Open Combustion (Portable)	Closed Combustion (Built-in)
Primary Fuel	Propane	Diesel or Propane
Air Quality	Risk of CO/CO2 buildup	Completely safe
Condensation	High (Wet heat)	Low (Dry heat)
Installation	None (Portable)	Required (Fixed)
Running Cost	High (Disposable bottles)	Very Low (Taps into main tank)

---

Final Thoughts

While a portable open-flame heater is a great “emergency backup,” a closed combustion system is the clear winner for full-time van life or winter camping. It provides a dry, safe, and “set-it-and-forget-it” warmth that makes a van feel like a home.

Those who use open combustion devices should do so with great care. Our products provide demand controlled ventilation based on our CO2 sensing controller. We don’t encourage the use of these devices in sealed spaces around our product. We make products that make fresh are for people and pets. Any open flame is competing with you for oxygen and we can’t bring in that much air.