The following experience report is about the Sigmar Marine 40 litre water boiler with the type designation B040 UCD, which we have installed in our camper ourselves and have now been using for several weeks. This report is not an advert for the manufacturer. We were not provided with a test model and were not paid for our opinion.

How the Sigmar Marine COMPACT works

There are many different types of water heaters on the market that are designed for use in motorhomes, campers and vans. The water can be heated using electricity, fuel, air or the waste heat from the engine. All systems have their advantages and disadvantages. From an ecological point of view, heating using waste heat from the engine makes the most sense. No additional energy is required to produce hot water. During the day you move around with the camper and when you arrive at your destination in the evening, the water supply in the boiler is heated up to 80-100 degrees. Depending on the model, in combination with the available fresh water, there are sufficient reserves for relaxed showers. The disadvantage of the system is that it is not used for long periods. This is where the 12V electric heating coil with an output of 1200W helps with the Sigmar Marine COMPACT.

What can the Sigmar Marine COMPACT do?

The water boiler was specially designed for the water sports sector, but also works perfectly in a camper. The water boiler is available in many different versions.
- Volume 20-60L in various gradations (our model: 40L capacity)
- With single or double heat exchanger
- Different power levels of the electric heating element (our model: 1200W)

How the Sigmar Marine COMPACT works

The water boiler has a total of six ½" threaded connections. Two connections are for the domestic hot water system (cold in, hot out). Two further connections are for the engine cooling circuit. The last two connections can be used variably. Either an additional heat source can be connected, for example another motor, or a circuit using solar thermal energy would also be conceivable. The connections can also be used to utilise an existing hot water heating system for domestic hot water heating.

The water boiler in our model has a 230V heating element with 1200W output. If a powerful inverter is available, the water can therefore be easily heated using electricity. The boiler has a thermostat that switches off the heating element when a temperature of 65 degrees is reached.

To avoid misunderstandings. The water circuit of the engine is not directly connected to the domestic hot water system. There is a tank in the water boiler through which the fresh water system runs. The heating circuit of the motor is channelled through the fresh water system via a heat exchanger. The two circuits therefore do not "come into contact" with each other.

How long does the heat in the Sigmar Marine COMPACT last?

Of course, this essentially depends on the outside temperature or the temperature in the vicinity of the boiler. During our test period, the outside temperature at night was between 0 and 10 degrees. If you arrive at your destination in the evening, there should be sufficient temperature for a shower or to wash the dishes by the next evening. The water remains hand-warm for approx. 48-72 hours. In our experience, two people can shower with the 40 litre capacity and still have enough heat for other things.

Connecting the Sigma Marine COMPACT to the engine

Our boiler was installed in the living area directly behind the driver's cab so that the distance between the engine and boiler is not too great. We installed two ½" fittings with 13 mm hose nozzles on the boiler. Two radiator hoses with a diameter of 13 mm lead from these hose nozzles into the engine compartment. These hoses must now be connected to the engine's cooling circuit at two points in the engine compartment.

We were advised not to interrupt the main cooling circuit of the engine directly. Most vehicles, or even lorries, have separate supply lines from the engine for the heating inside the driver's cab. Interrupting this circuit for the boiler has two advantages. Firstly, these hoses have a smaller diameter than the main circuit. This means that the 13 mm hoses can be better integrated into the system. Secondly, the cab circuit only opens once the engine circuit has reached a sufficient temperature.

In our system, we have extended the hoses of the circuit for the driver's cab (blue in the picture) and moved them to a location in the engine compartment where there is sufficient space for distribution. We used two ¾" T-pieces and two ball valves. We used 19mm ¾" hose nozzles in the driver's cab circuit and 13mm ¾" hose nozzles in the direction of the boiler. The ball valves offer the advantage that in the event of a defect or for maintenance work, the circuit to the boiler can be interrupted in two simple steps.

Does the performance of the engine change?

The performance of the engine does not change in any way. We have also not noticed any changes in the engine temperature, e.g. whether it warms up later or similar.

How quickly does the water in the Sigmar Marine COMPACT heat up?

The good thing is - you don't have to drive for long. In our experience, the water in the boiler is lukewarm after just a few kilometres. We recommend a journey time of one hour to heat the boiler to the full temperature of around 90 degrees. However, this may vary depending on the model of vehicle.

Conclusion

We are really enthusiastic about the Sigmar Marine COMACT water boiler. There is probably no simpler and more sustainable way to heat domestic hot water. Of course, there is some additional work to be done when installing the boiler, such as connecting it to the engine. Connecting to the motor, i.e. changing or adapting an existing cooling system, is also not to everyone's taste. We also had our reservations and some respect for the installation. But in hindsight, everything worked perfectly and we can take a hot shower with a clear conscience!

Advantages and disadvantages at a glance

Pro:
	Sustainable - no energy required
	Price/performance in order
	Keeps the water warm for up to 72 hours
	Always warm water when travelling regularly
	Alternatively heatable with electricity
Contra:
	No hot water for longer periods
	More complex installation compared to 230V boilers
	Cooling circuit of the vehicle must be modified

Prize of the Sigmar Marine COMPACT in April 2023: 749 €
To order for example from www.svb.de

Do you have any questions? We are happy to answer all your questions. Just write to us using the contact form!
Find out more about our campervan conversion here.