This article and video demonstrate what a frost protector valve does and how to reset it.
Your Benimar motorhome has a frost protector valve which will dump water from the pipes in below zero temperature.
When your Truma heating systems detects a minus temperature, which could result from being parked up in extremely cold conditions such as snow or a heavy frost, the Frost Protector Valve will open and dump the water from your pipes onto the ground.
This is to protect water freezing in your pipes and causing damage. You will know this has happened if you see water on the ground under your motorhome and no water is coming out of your taps.
This can also happen if the motorhome has not been used in a while.
This Frost Protector Valve needs to be manually reset so you can use your taps again.
If you are parked up during a heavy frost or in the snow and you have your hot water and heater on, the Frost Protector Valve will not open. However, at night if you turn your heater and hot water off, also turn off your water pump. The reason for this is the valve will not only dump the water in pipes but will empty your tank as well if the water pump is left on.