All of us need hot water for a comfortable rest. Hot water in caravans can be used to heat water in a kettle on the stove, or you can spend money and install a high-tech caravan boiler.
Boilers differ in the power supply system: electric and gas.
Electric boilers (Truma and other manufacturers) are cheaper than gas, simpler in construction, compact, quite fire safe.
But to power these boilers you need to connect to 220V, which significantly limits their use. For autonomous work, you will need a powerful fuel generator (which will rattle, eat fuel, and maybe even be stolen the next night), or a powerful storage battery (preferably several) an inverter and solar panels. In other words, to modify the system to autonomy is quite expensive.
A gas boiler (produced by Truma, Carver) is significantly more expensive in terms of cost, but only natural gas and 12V (for supplying a spark) are needed for its operation.
Gas boilers heat water much faster than electric ones. The device of gas boilers is more complicated than electric and requires periodic maintenance. It also requires a safe gas supply and exhaust. More fire hazard. Like all gas appliances in the cold suffers because of the freezing of gas in the cylinder.
There are also boilers-heat exchangers, built into the heating system of the motorhome (from manufacturers Alde, Primus, Truma).
In such boilers, water is heated by taking heat from the heating medium of the heating system (liquid or air). In liquid heating systems, it is also possible to shut off the coolant circulation system to a small circulation circle, which passes only through a heat exchanger (so that in summer, using a common heating system, only heat the water in the boiler and not heat the entire residential trailer).
Also, such heat exchangers are equipped with electric heaters for heating water, in case there is a connection to an external 220V source.
There is the option of using household gas flow heaters in trailers cottages.
Their significant plus is a very small cost. But when installing such a system, you need to be smart and find a suitable attachment point, take into account the correct exhaust gas flow and supply of natural gas. It is also necessary to reduce the power of the burner (stop half of the nozzles, otherwise the water in the boiler will simply boil) and reconfigure the sensor to a lower switching pressure in the water supply.
Also boilers for water heating are divided according to the principle of operation: flow and accumulative.
Flow boiler has small dimensions and weight. The water in the boiler heats up instantly as it arrives with a powerful electric shade or gas burner. When the boiler is running, the consumption of electricity or gas will be significant.
Cumulative boilers significantly exceed flow dimensions. The water is heated by a low-power electric heater (gas burner) slowly and continuously in a special reservoir of limited volume (about 7-13 liters). When the hot water supply is turned on, cold water enters the heating tank and displaces the hot water, the heating process starts anew until the next power up. The advantage of this principle of operation is a significant saving of electricity (gas). Among the shortcomings can be noted the time to wait for the heating of the next portion of water, as well as large sizes.