Truma Combi 4 E connections

This entry is the Combi 4 E gas/electric space and water heater. It needs a 12 V supply for electronics and the circulation fan even when heating from 230 V. The technical data, page 22, gives 1.2–6.5 A at 12 V for Combi 4 (E), plus separate electric-heater stages of 900 W/3.9 A and 1800 W/7.8 A at 230 V. The catalog uses the upper 6.5 A DC demand. Gas heat output of 2 or 4 kW is not electrical draw; the electric heating element is a separate shore-power load.

The connector diagram, page 20, identifies terminal 40 as +12 V and 41 as ground, both 6.3 mm spades. Its internal F10A quick-acting fuse is separate from the branch-protection instruction on page 21: connect to a 10 A fused on-board circuit, using 2 × 2.5 mm² cable, or 2 × 4 mm² for 6–10 m total cable length. The stated maximum total length is 10 m. No other consumers should share this supply line.

When connected directly to the battery, page 21 requires protection of both positive and negative leads. Follow this installation-specific arrangement rather than treating the drawing as a generic positive-fuse-only branch. The catalog's 10 A DC-terminal boundary represents the specified protected supply; it is not a measured load.

The 230 V instructions, page 21, require a circuit rated at least 10 A, preferably 16 A, a suitable residual-current device and an all-pole maintenance disconnect with at least 3.5 mm contact separation. AC L, N and PE are shown separately in the catalog. Keep mains and low-voltage wiring apart, and have the gas and mains installations completed and tested by qualified installers.

Check gas tightness, secure exhaust and combustion-air connections, unobstructed warm-air outlets and room-sensor placement. Fill and check the water system, then test draining through the frost-protection valve. The tank's 10 L capacity is not protection against freezing: drain according to the operating instructions whenever frost exposure is possible. If heating stops, check both supplies and the actual controller fault code; increasing a fuse rating is not a remedy for a recurring fault.