Very little. Inside keep an eye on the pressure gauge
on the pumping station. It should be around 3 to 5 bar. Fluctuations in the
course of use are quite normal but if the gauge shows no pressure please
contact your installer.
Every month you should check visually that nothing has gone wrong outside.
Every three years the integrity of the glycol can be checked and tested.
Vacuum panels should be checked for the quality of the vacuum every two
years and re-evacuated every five years.