Glossary 110020135485_00 VRT 350 Operating instructions 3311.16 Time periodsA time period is a preset, defined time period in which theheater or the hot water generation are switched on.11.17 Timer programWith timer programs, you can control your heating installa-tion in such a way that heating and hot water are already inthe set time periods with the set desired temperature.11.18 Access level for the operatorThis access level contains all the functions that the oper-ator is allowed to change.11.19 Access level for the competent personThis access level contains all the additional functions thatcan be changed by the competent person; these must notbe changed without specialist knowledge. This access levelis reserved for the competent person and is therefore pro-tected by an access code.