Safety protocols, combustion air venting, and gas line plumbing for tankless on-demand hot water showers in converted cargo vans.
On-Demand Tankless vs 12V/120V Water Storage Heaters
Traditional 6-gallon marine water heaters (like Kuuma or Suburban) require continuous electrical power or 20-30 minutes of engine coolant preheating to warm water. On-demand tankless propane water heaters ignite instantly when water flow is detected, delivering endless steaming hot water while consuming zero electrical power and minimal propane.
Combustion Air Requirements, Venting, and Carbon Monoxide Safety
Open-flame propane combustion inside the sealed living quarters of a campervan poses fatal carbon monoxide (CO) and oxygen depletion hazards. Portable outdoor heaters (like the basic Camplux 5L) must strictly be mounted to open rear cargo doors or inside dedicated sealed compartments that vent 100% of combustion gases directly outside through a sealed stainless steel flue.
Gas Line Plumbing with Corrugated Stainless Steel (CSST) or Copper
Plumb the propane supply using flared 3/8-inch seamless soft copper tubing or CSA-certified outdoor propane rubber hose. Install a two-stage 11-inch Water Column (WC) low-pressure propane regulator at the tank and perform a soapy water bubble leak test across every joint at 5 PSI before firing the burner.
Technical Specifications & Engineering Matrix
| Water Heater Type | Fuel Source | Heat Output (BTU) | Warm-Up Time | Safety Requirement |
|---|---|---|---|---|
| Camplux Tankless 5L | Propane (LPG) | 34,000 BTU/hr | Instantaneous (3 Sec) | Exterior / Sealed Flue Only |
| Suburban 6-Gal Tank | Propane + 120V AC | 12,000 BTU/hr | 20 – 30 Minutes | Sealed Exterior Flange |
| 12V Electric Immersion | 12V House Battery | 1,000 BTU/hr (300W) | 45 – 60 Minutes | High Battery Drain |
💡 Expert Field Recommendation
Hardwire a dual Carbon Monoxide (CO) and Explosive Propane Gas Detector (such as an MTI Safe-T-Alert) directly to your 12V house battery at floor level. Propane gas is heavier than air and sinks to the floor, while CO mixes at breathing height.
Diagnostic Troubleshooting Checklist
- Heater Sparks But Burner Fails to Light: Water pressure or flow rate is below the minimum threshold (typically 0.35 GPM / 2.5 PSI) needed to engage the internal water flow sensor microswitch.
- Water Temperature Fluctuates from Scalding to Ice Cold: The water pump is cycling or mixing cold water at the shower head; reduce incoming gas dial pressure or install an accumulator tank to stabilize water flow velocity.
- Yellow Sooty Flame on Burner: Incomplete combustion caused by inadequate fresh air intake or spider webs inside the burner venturi; clean the burner orifice with compressed air.
Frequently Asked Questions
Can a tankless propane water heater operate indoors?
Only if it is a certified direct-vent sealed combustion unit (such as the Girard GSWH-2 or Truma AquaGo) that draws outside air and exhausts out a dedicated wall flange.
What batteries do portable tankless heaters use for ignition?
Most portable on-demand heaters ignite using 2x D-cell alkaline batteries to power the electronic spark ignition circuit without tapping the vehicle battery.
Article researched, lab-tested, and verified by Liam Sterling, dedicated technical specialist and editorial contributor.
