In winter caravans from Swedish and Finnish manufacturers Kabe, Solifer, Cabby, Polar, as well as on trailers of European manufacturers Kip, Avento, LMC, Adria and others with a winter package (gas heating with a liquid heat carrier), it is not uncommon to find an adjustable gas reducer. Why is it needed and how to correctly set its values?
Since 1990, all European manufacturers began to switch (for security reasons) to a working pressure in the gas line of 30 mbar, instead of the early 50 mbar. This means that all gas appliances (heater, hob, fridge, water boiler) are designed for the pressure of incoming combustible gas - 30 mbar. The Scandinavian caravans situation was different. The gas-fired heating system Primus and Alde installed on them for work efficiency in severe frosts still needed an inlet gas pressure of 50 mbar. Therefore, opening the front lock of the winter caravan for the first time can be a bit confused. A picture of a cluttered gas pipeline opens. But everything is quite simple. First, a gas pressure regulator with a working pressure of 50 mbar is put on the cylinder, then the gas line passes through the absorber (flask with liquid) and is divided after it. One branch goes to the boiler, and the other is put on the gearbox for 30 mbar and then goes to the other gas devices.
The problem is that at a pressure of 50 mbar the boiler becomes very powerful (up to 6 kW) and consumes an impressive amount of gas. This is true when operating in harsh winter conditions, but for moderate temperatures it becomes unprofitable. Say in the summer season, you only need to warm the shower water in the heat exchanger, but not the caravan itself. Or a little warm it on cool nights in August. On early models of the Primus boiler (2450, 2470, 2480) there were 3 burners. One burner worked continuously, and the other two were disconnected mechanically. This made it possible to more precisely adjust the economical operation of the Primus boiler, relative to the external temperature. The late model Primus 2490, as well as all Alde boilers, has only one burner. To ensure economical gas flow and apply an adjustable gearbox. If you look at the end of the rotary washer of the gearbox, you will see divisions from 1 to 12, which corresponds to a smooth increase in pressure in the gas line from 20 mbar to 50 mbar. Thus, in the summer period for heating water in the built-in boiler-heat exchanger or lightly heating the trailer, you can set the regulator of the reducer into divisions 1 and 2. At the same time, the heating power of the gas boiler can be about 3 kW. If it is necessary to be heated in moderate autumn-winter weather, it is more logical to place the regulator on the divisions 5-6 (4-5 kW power, respectively). Well, if you decide to spend the winter in the trailer for real, then in extreme cold it will be necessary to use the full power of the gas boiler, dividing 11-12 (boiler power 6 kW, respectively).