When sourcing a Truma Combi system, you must prioritize energy source compatibility (LPG, Electric, or Diesel versions). Ensure the unit provides a heat output of at least 4kW to 6kW for standard motorhomes. Key technical benchmarks include a 10-liter stainless steel water tank, a short heating time (approx. 20 minutes from 15°C to 60°C), and low power consumption (averaging 1.1A to 5.6A). For high-altitude performance, verify if the unit includes an integrated altitude sensor for operation up to 3,000 meters.