Inspection And Maintenance; Inspection; Maintenance; Maintenance Intervals - Bosch Stora WS 300-5 PK Installation And Service Instructions For Contractors

Inspection and maintenance

9 Inspection and maintenance
WARNING
Risk of scalding from hot water!
Hot water can cause serious burns.
▶ Allow the cylinder to cool down sufficiently.
▶ Allow the cylinder to cool down sufficiently before carrying out any

maintenance.

▶ Carry out cleaning and maintenance procedures in the specified
intervals.
▶ Remedy all faults immediately.
▶ Only use genuine spare parts!
9.1

Inspection

An inspection/check of the cylinders must be carried out every 2 months
in accordance with DIN EN 806-5. During this the set temperature
should be checked and compared with the actual temperature of the
heated water.
9.2 Maintenance
Annual maintenance should be carried out in accordance with DIN EN
806-5, Appendix A, tab. A1, line 42. This includes the following work:
• Function check of the pressure-relief valve
• Tightness test of all connections
• Cleaning of the cylinder
• Checking of the anode
9.3

Maintenance intervals

The maintenance to be carried out depends on the flow rate, operating
temperature and water hardness ( Tab. 8). We recommend the
maintenance intervals specified in tab. 8 which are based on many years
of experience.
The use of chlorinated potable water or a water softener unit reduces the
maintenance intervals.
You can check the water quality with your water supply utility.
Depending on the composition of the water, it can make sense to deviate
from the reference values listed.
Water hardness [°dH]
Calcium carbonate
concentration CaCO [mol/m3]
3
Temperatures
At a normal flow rate (< cylinder content/24 h)
< 60 °C
60...70 °C
> 70 °C
At an increased flow rate (> cylinder content/24 h)
< 60 °C
60...70 °C
> 70 °C
Table 8 Maintenance intervals in months
9.4

Maintenance work

9.4.1

Testing the pressure relief valve

▶ Check the pressure relief valve annually.
9.4.2

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.
54
3...8.4 8.5...14 > 14
0.6...1.5 1.6...2.5 > 2.5
Months
24 21 15
21 18 12
15 12 6
21 18 12
18 15 9
12 9 6
▶ 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. 25, page 74).
▶ Drain the cylinder ( Fig. 24, page 74).
▶ 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. 28, page 75).
▶ Use a wet & dry vacuum cleaner with plastic suction hose to remove
the residues.
▶ Close the inspection aperture with a new gasket
( Fig. 29, page 75).
9.4.3

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. 33, page 76).
• An insulated magnesium anode ( Variant B, Fig. 33, page 76).
We recommend that insulated magnesium anodes are additionally
checked regarding the protection current using an anode tester on an
annual basis ( Fig. 31, page 76). 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.
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. 23, page 74).
▶ Remove and test the magnesium anode ( Fig. 32 to Fig. 35,
page 76).
▶ 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. 31, page 76).
9.4.4

Recommissioning

▶ Flush the cylinder thoroughly after cleaning or repair.
▶ Vent on the heating side and on the domestic water side.
Stora – 6720821526 (2021/06)