Hobby boiler not producing hot water: what's going on?

A Hobby motorhome or camper is standardly equipped with a Truma Combi (combination of heating and boiler on gas and/or 230V), or on the more expensive models with an Alde system (heating via central heating fluid with integrated hot water boiler). Sometimes there is also a separate Truma boiler (e.g., a Boiler Elektro or Gas) installed. Each system has its own typical faults, but the symptoms are similar: you turn on the tap and only cold water comes out.

Always start with the simplest checks. Is there enough gas in the cylinder and is the gas tap open? For electric operation: is the plug in the socket, is the fuse in the camper still good, and has the residual current device not tripped? Also check whether the boiler is filled with water (bleed the system via the hot water tap) and whether the water pump works. An empty boiler or a stuck safety valve can block operation.

Diagnosis by power source

• Gas operation (Truma Combi or separate boiler): Do you hear the ignition clicking but the flame does not ignite? Then often the ignition electrode is dirty or worn, or the gas pressure is too low. If the flame ignites but goes out quickly, the flame safety device (thermocouple) may be faulty. With a completely silent boiler, the circuit board or the gas regulator is suspect.
• Electric operation (230V): If the boiler does not heat up on electricity, but does on gas, then usually the heating element (immersion heater) has burned out. This is a known issue with intensive use. Measure the resistance of the element; if it is infinite, it is broken. The thermostat or a relay on the circuit board may also be faulty.
• Alde system: Here, a central heating boiler (gas or electric) provides hot water via a heat exchanger. No hot water often points to an air lock in the central heating circuit, a faulty circulation pump, or a broken 12V supply to the control unit. Also check the expansion vessel and the central heating pressure.

For a complete step-by-step plan and more background on all possible causes, read our general explanation about a camper boiler that does not give hot water. There you will also find tips for descaling and maintenance, which can prevent many problems.

What can a repair cost? A new heating element for a Truma boiler costs roughly between 100 and 200 euros, excluding installation. A new circuit board or gas regulator can go up to 300 to 500 euros. With an Alde system, a faulty circulation pump is usually 150 to 250 euros. Add to that 1 to 2 hours of labour at a usual hourly rate. Sometimes the issue is simple to solve, such as a scaled-up safety valve or a loose plug, and it costs you almost nothing.

If the diagnosis becomes too complex or the repair is no longer economically viable, you do not have to keep struggling. We buy campers in any condition, even with a faulty boiler. Feel free to request a free valuation of your motorhome or see how you can sell your Hobby easily.