Viessmann VITOTRONIC 100 GC1 Installation And Service Instructions Manual page 86

Start-up
Steps
(continued)
2. Check the fixed high limit
86
The check is made via the "TUV button" (see page 85).
When making the check, the "TUV"
button must be kept continuously
pressed.
A minimum supply is required during
the check.
The minimum amount of recirculated
water should be 10% of the amount
recirculated at the rated load.
The amount of heat consumed should
be reduced as far as possible.
The adjustable high limit "R" is
bridged. The burner is switched on
until the boiler water temperature
reaches the safety temperature and
the fixed high limit operates.
When the burner is switched off by
the fixed high limit, release the "TUV"
button, wait until the boiler water
temperature has fallen 15 to 20°C / 27
to 36°F below the selected safety
temperature and then reset the fixed
high limit by pressing the "E" button.