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Inspection and maintenance
10.4
Maintenance work
10.4.1 Testing the pressure relief valve
▶ Check the pressure relief valve annually.
10.4.2 Descaling and cleaning
In order to improve the cleaning effect, heat up the heat exchanger prior
to cleaning it with a water jet. The thermal shock effect separates
deposits (e.g. limescale) more readily.
▶ Isolate the cylinder from the piping on the domestic water side.
▶ Close the shut-off valves and isolate the immersion heater (if used)
from the mains power supply. ( Fig. 17, page 69).
▶ Drain the cylinder ( Fig. 16, page 69).
▶ Open the inspection aperture on the cylinder.
▶ Check the interior of the cylinder for pollution.
-or-
▶ In the case of soft water:
Check the container regularly and clean to remove limescale.
-or-
▶ In the case of hard water or severe pollution:
Regularly descale the cylinder in line with the actual amount of
limescale using chemical cleaning methods (e.g. with a suitable
descaling agent based on citric acid).
▶ Hose down the inside of the cylinder ( Fig. 20, page 70).
▶ Use a wet & dry vacuum cleaner with plastic suction hose to remove
the residues.
▶ Close the inspection aperture with a new gasket
( Fig. 21, page 70).
10.4.3 Checking the magnesium anode
Failure to service the magnesium anode properly voids the warranty for
the cylinder.
The magnesium anode is a sacrificial anode, which is consumed when
the cylinder is in operation. Two types of magnesium anode can be used.
• A non-insulated magnesium anode ( Variant A, Fig. 25, page 71).
• An insulated magnesium anode ( Variant B, Fig. 25, page 71).
We recommend that insulated magnesium anodes are additionally
checked regarding the protection current using an anode tester on an
annual basis ( Fig. 25, page 71). The anode tester is available as an
accessory.
NOTICE
Corrosion damage!
If the anode is neglected, this could lead to premature corrosion.
▶ Inspect the anode every one or two years, depending on the on-site
water quality, replace if required.
48
Never bring the magnesium anode surface into contact with oil or grease.
▶ Keep everything clean.
▶ Shut off the cold water inlet.
▶ Depressurise the cylinder ( Fig. 16, page 69).
▶ Remove and test the magnesium anode ( Fig. 24 to Fig. 24,
page 71).
▶ Replace the magnesium anode if its diameter has been reduced to
less than 15 mm.
▶ If the magnesium anode is insulated: check the transfer resistance
between the protective conductor connection and the magnesium
anode. If the anode current is <0.3 mA, replace the magnesium
anode ( Fig. 25, page 71).
10.4.4 Recommissioning
▶ Flush the cylinder thoroughly after cleaning or repair.
▶ Vent on the heating side and on the domestic water side.
10.5
Function check
NOTICE
Damage through positive pressure.
A pressure-relief valve malfunction can result in damage due to positive
pressure.
▶ Check the pressure-relief valve function and flush through several
times by venting.
▶ Never close the blow-off opening of the pressure-relief valve.
Stora – 6721839992 (2022/07)
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