Rooms Are Too Hot; There Is No Hot Water - Viessmann VITODENS 100-W Operating Instructions Manual

What to do if...

Rooms are too hot

Cause
Control unit or room temperature control
unit incorrectly adjusted.
The "U" symbol is shown on the display.

There is no hot water

Cause
The heating system is off.
Control unit incorrectly adjusted.
No fuel.
The "U" symbol is shown on the display.
Symbol "U" flashes on the display. The
burner does not start.
18
Remedy
Check and correct the room temperature
or boiler water temperature (see
page 13).
Room temperature control unit op-
erating instructions
Notify your heating contractor of the fault
code.
Remedy
■ Turn on the ON/OFF switch " " (see
page 8).
■ Switch ON the mains isolator, if instal-
led (outside the boiler room).
■ Reset the MCB in the power distribution
board (main domestic MCB).
Check settings and correct if required:
■ "tw" has to be adjusted (see
page 13).
■ Check and correct the DHW tempera-
ture at rotary selector "tw" (see
page 13).
With LPG:
Check the fuel reserves and re-order if
required.
With natural gas:
Open the gas shut-off valve. If necessary,
check with your gas supply utility.
Notify your heating contractor of the fault
code shown.
Reset the burner fault (see page 20).