Diesel additional heater retrofit

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Updated – January 20, 2023

In colder climes, it is generally recommended to install an additional diesel heater in addition to the existing ALDE water heater. This is because you probably fill up more often than you will find filling or exchange stations for gas bottles in more distant countries.

Well, additional heaters, be it Webasto or Eberspächer, to name two of the most well-known providers, are known from various cars, vans, etc. They usually heat the water in the vehicle's cooling circuit. Its heat is then supplied to the vehicle interior via the ventilation heat exchanger.

In a motorhome, however, you don't want to heat the engine so much as you want to heat the living area. The gas-powered ALDE water heater takes this into account. It heats the antifreeze circulating through the installed radiators, be it using an electric heating cartridge or gas.

In both cases, the desired room temperature is selected via a central thermostat controller. The type of heating is determined via separate switches for electric or gas heating.

Diesel additional heater – workshop search

A diesel additional heater from the car sector has its own control panel, which can also be used to set the switch-on time, duration and temperature, which can also be controlled remotely.

In the motorhome, however, you would ideally still like to use the existing ALDE control for the diesel auxiliary heater and have the option of switching both the pump and the engine heating on or off.

The company has taken on this task Steitz was adopted in Groß-Gerau over ten years ago and has been implementing it exactly the same way ever since, including a second exhaust silencer to ensure even more peace and quiet at night.

Groß-Gerau isn't exactly around the corner from us, which is why various inquiries were initially sent to local workshops certified for diesel additional heaters. All offers were priced at around 3,800 euros.

Immediately in Hamburg we received a short-term appointment to assess the structural conditions. However, when specifically asked, it was said that the desired integration of the ALDE control, in particular the switchable engine heating, could not be implemented. The fact that the intended version was not the “Camper”, but the standard car version, was not even mentioned. The same tenor was consistently heard at all other specialist workshops requested.

So the choice fell on Steitz, a company that was far away from us.

Webasto Thermo Top – Caravan version

The Webasto Thermo Top Caravan is designed as a continuous runner, while the other versions allow an uninterrupted operating time of only a maximum of 60 minutes.

Integration into the existing ALDE heating system takes place via an existing heat exchanger and its own water pump. This means the ALDE system remains untouched. A switchable solenoid valve to shut off the engine circuit is also installed.

The heat exchanger located between the driver and front passenger seat, which is usually switched on while driving in order to use the engine heat to heat the interior, now remains permanently connected to the circuit. In this way, when the diesel auxiliary heater is in operation, the heat generated enters the ALDE circuit and heats the radiators in the same way.

The vehicle's own fan can be switched on at any time to warmly ventilate the space between the windshield and the lowered roller shutter and prevent condensation from forming. This can also be automated via SmartHome.

Specially tailored control unit

A standard control unit is configured in such a way that the burner is switched off when the target temperature is reached and switched on again when it falls below it.

Since the current requirement for the starting process is around 15 A, and current in mobile homes is usually rather limited, the Steitz company has implemented a modified control algorithm in collaboration with the Webasto company. This is based on continuous operation - which is permissible in this version - with multi-stage power adjustment depending on the room thermostat setting.

If the ALDE thermostat switches off, the ALDE circulation pump stops. The temperature on the Webasto heater rises, which is why the diesel heater reduces its output to around 1.2 kW. If the temperature falls below the set target, the circulation pump is switched on again, the water temperature of the Webasto heater drops, which is why it gradually increases its output and adapts it to the heat requirement within its entire performance range.

In this operating mode, the average diesel consumption is 0.3 liters per hour, which means the daily requirement is 7.2 liters.

The implementation

The arrival took place on Sunday evening. You can stay overnight on the factory property, including shore power supply.

Work begins at 8:00 a.m. in the morning. You are not allowed to stay in the vehicle during installation, but - by arrangement - you are allowed to return to the motorhome from 5:00 p.m. and spend the night there. In the meantime, a rental vehicle can be made available upon request or you can stay in the heated office container, equipped with very comfortable armchairs.

The work will be completed on the second day of installation. The additional heater is subjected to an endurance test on the second night. If everything is successful, you can start the journey home.

Conclusion

Taking the approximately 1,200 km route was worth it!

Mr. Steitz, his son and the employees do careful and professional work. The expertise acquired from more than a decade of experience is clearly noticeable. You know what you are doing and how. In comparison to other companies that we have previously contacted and were on site, here we don't spend a lot of time puzzling around, but rather clearly formulate the offer, create the work, do the invoicing (which has to be paid in cash) and generate full customer satisfaction.

Everything without ifs and buts – friendly, quick, reliable, simply perfect. What more do you want?!