Heating & Hot Water Basics (Truma-Style Systems)
Many Mars caravans use combined systems for space heating and hot water (model dependent). This guide covers the typical “how it works”, warm-up expectations, and the common reasons it won’t heat.
Exact controls and icons vary by unit. If your unit shows an error code, photograph it for your ticket.
What to expect (normal behaviour)
- Hot water can take time to heat (especially from cold start).
- Space heating fan noise is normal.
- In cold conditions, warm-up time increases.
Power/fuel sources (depends on your system)
- Gas: commonly used for heating/hot water
- 240V: some systems support electric heating elements when on shore power
- 12V: controls and fans often need 12V even when heating on gas/240V
Fast troubleshooting (common fixes)
- Confirm 12V system is ON and battery is not extremely low.
- If using gas: confirm bottle is ON and has gas.
- If using 240V mode: confirm shore power is live and breakers are ON.
- Turn the system OFF for 60 seconds, then ON again.
- If there’s an error code/icon: note it and take a clear photo.
Common causes
- No gas supply (bottle off/empty)
- No 12V supply for fan/control
- 240V not available (RCD/breaker trip)
- System not given enough warm-up time
What to include in a support ticket
- Mars model + year
- System brand/model (photo if possible)
- What you’re trying to do: hot water or space heat
- Which energy mode: gas or 240V
- Photo of control panel showing any error code/icons
- Battery monitor photo (voltage/%)