Viessmann Vitodens 100-W B1HA 26 Installation And Service Instructions Manual page 58

Start-up, Inspection and Maintenance
Cleaning the DHW Heat Exchanger
Legend
A Vitodens 100 B1KA
B Circulating pump (field supplied)
C Cleaning solution (field supplied)
D DHW discharge hose (field supplied)
E DCW inlet hose (field supplied)
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Vitodens 100-W, B1HA/B1KA 26 to 125 Combi Installation/Service
The brazed plate heat exchangers operate with high
turbulence flow, even at low flow rates. This high
turbulence keeps small particles in suspension minimizing
fouling and scaling. In some applications the fouling can
be very high (e.g. when using extremely hard water at
high temperatures). It is always possible to clean the heat
exchanger by circulating a cleaning solution. For optimum
cleaning, the cleaning solution flow rate should not
exceed the normal flow rate. Clean at regular intervals.
Note: Only chemical cleaning is possible (use chemicals
which do not attack copper and stainless steel).
Consult a plate heat exchanger cleaning specialist.
1. Disconnect electrical power to the boiler.
2. Close the shutoff valves and isolate boiler water
from both heating system and domestic cold water in.
3. Pour approximately 5 gallons of new, food grade,
white vinegar or citric acid into a pail.
4. Place the discharge hose D and hose E (connected
to the pump inlet) into the pail of cleaning solution.
5. Attach other end of the hoses D and E to the heat
exchanger.
6. Open both drain valves.
7. Operate the pump and allow the cleaning solution
to circulate through the DHW portion of the heat
exchanger for at least 60 minutes. Then turn off the
pump.
8. Empty the pail and fill with clean potable water.
Rinse the cleaning solution from the DHW heat
exchanger by circulating clean water through it for
at least 7 minutes. Repeat if necessary.
9. Close the drain valve, disconnect both hoses and
return the system into operation.