Checking The Indoor Unit Electrical Connections For Firm Seating; Checking The Outdoor Unit Electrical Connections For Firm Seating; Resetting The High Limit Safety Cut-Out - Viessmann VITOCAL 151-A Installation And Service Instructions Manual

Commissioning, inspection, maintenance
Cleaning the DHW cylinder
5. Use a chemical cleaning agent to remove hard
deposits that cannot be removed with a high pres-
sure cleaner.
!
Please note
Cleaning agents containing hydrochloric acid
will attack the DHW cylinder material.
Only use pH-neutral cleaning agents.
Danger
Cleaning agent residues can result in poi-
soning.
Fully drain all cleaning agent.
Always observe the information provided by
the cleaning agent manufacturer.

Checking the indoor unit electrical connections for firm seating

Checking the outdoor unit electrical connections for firm seating

Danger
Contact with live components can lead to seri-
ous injury from electric current. Some compo-
nents on PCBs remain live even after the power
supply has been switched off.
■ When working on the outdoor unit, isolate the
system from the power supply, e.g. at a sepa-
rate MCB/fuse or a mains isolator. Check the
system is no longer live and safeguard against
reconnection.
■ Prior to working on the appliance, wait at least
4 min until the voltage on the charged capaci-
tors has completely dropped out.

Resetting the high limit safety cut-out

A
Fig. 69
High limit safety cut-out reset button
A
90
(cont.)
6. Flush the DHW cylinder thoroughly after cleaning.
7. Fit the protective magnesium anode.
!
Please note
A short circuit between the protective mag-
nesium anode and the indirect coil negates
the protective effect of the magnesium
anode. This leads to corrosion damage on
the DHW cylinder.
Before connecting the cables, check the
resistance across terminals
resistance is significantly less than infinity,
check whether the protective magnesium
anode is touching the indirect coil.
!
Please note
If the heat pump is exposed to temperatures
below 10 °C, e.g. during storage or transport,
–
the high limit safety cut-out of the instantaneous
heating water heater may respond. In this case,
the instantaneous heating water heater will not
heat up.
Heat up the high limit safety cut-out to above
20 °C. Press the reset button of the high limit
safety cut-out.
Note
The high limit safety cut-out can only be reset if the
temperature at the sensor is below 82 °C.
and . If the
A B