Wolf FWS-2-60L Instructions De Montage page 41

Protection against scaling
Chemical descaling
3064928_201607
Scaling protection - chemical descaling
To protect against scale build-up, the thermostatic head should be set to no
more than 3.25, which corresponds to around 50 °C in the nominal range,
when the total water hardness is 15 °dH (2.5 mol/m³) or higher.
In accordance with the Drinking Water Ordinance [Germany], this is the
lowest permissible value for DHW temperatures, given that it practically rules
out the risk of legionella proliferation with daily use of the hot water system.
If the total hardness is 20 °dH or higher, the use of a water treatment facility
in the cold water supply line when heating DHW is essential in order to
prolong the maintenance interval. Even if water hardness is below 20 °dH,
a higher risk of scale build-up may occur locally, necessitating suitable
softening measures. Failure to take such measures will result in premature
scaling of the appliance and reduced DHW convenience. The contractor
should always check the local conditions.
1. The freshwater module is cleaned using a circulation procedure:
With this type of descaling, hoses are used to form a circuit with the
freshwater module being cleaned and the pump containing the descaling
material. The cleaning agent is then pumped through the module in a
circulation process.
2. Use only manufacturer-approved descaling agents. (Sulphamic acid-
based descaling powder, heat descalers). Other chemicals may destroy
the module.
3. Mix the powdered cleaning agent with 5-15 % fresh water to create a
solution.
4. Disconnect the freshwater module from the power supply so that the
pump cannot run during flushing.
5. Fully separate the domestic hot water side of the freshwater module
from the pipework at the union nut (including DHW circulation).
6. Connect the cleaning agent feed to the cold water connection and the
drain to the hot water connection. Do NOT change the direction. Doing
so may damage the flow switch.
7. Let the flushing process run for 6 - 8 hours.
8. The freshwater module may heat up. This is normal, because the
chemical reaction in the freshwater module and the DHW circulation
pump generate heat.
9. The pH value of "fresh" cleaning agent is 1.2. The cleaning will cause
the pH value to rise. If the pH value rises above 2.5 - 3, add cleaning
agent to return it to the original value.
10. Once cleaning is complete, flush the freshwater module with copious
amounts of water. This lengthy flush is required to ensure that no
cleaning agent remains in the module.
11. Reconnect the freshwater module correctly.
12. Neutralise the cleaning agent after use (pH = 7) and dispose of it in the
public sewer system.
13. Follow the instructions on the material safety datasheet supplied with the
product.
41