Maintenance; Maintenance Intervals; Maintenance Work; Checking The Safety Valve - Buderus SU120.5 Installations- Und Wartungsanleitung

9

Maintenance

▶ Let the DHW cylinder cool down sufficiently prior to any maintenance
work.
▶ Carry out cleaning and maintenance procedures in the specified
intervals.
▶ Remedy all faults immediately.
▶ Only use genuine spare parts.
9.1

Maintenance intervals

Service the appliance in accordance with throughput, operating
temperature and water hardness ( Table 8, page 39).
The use of chlorinated DHW or a water softener unit reduce the service
intervals.
Water hardness in °dH
Calcium carbonate concentration
in mol/ m³
Temperatures
At a standard throughput (< cylinder content/24 h)
< 60 °C
60 – 70 °C
> 70 °C
At a higher throughput (> cylinder content/24 h)
< 60 °C
60 – 70 °C
> 70 °C
Table 8 Service intervals in months
You can check the local 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.
9.2

Maintenance work

9.2.1

Checking the safety valve

▶ Check the safety valve annually.
9.2.2

Descaling/cleaning the DHW cylinder

In order to improve the cleaning effect, heat up the
indirect coils prior to cleaning them with a water jet. The
thermal shock effect separates deposits (e.g. lime scale
build-up) more readily.
▶ Disconnect the DHW cylinder on the DHW side from the pipework.
▶ Close the shut-off valves and isolate the immersion heater from the
power supply (if installed) ( Fig. 17, page 64).
▶ Drain the DHW cylinder ( Fig. 15 and 16, page 64).
▶ Check the DHW cylinder interior for contamination (lime scale
deposits, sediment).
▶ In the case of soft water:
Check the cylinder interior regularly and clean out any sediment
deposits.
-or-
▶ In the case of hard water or severe contamination:
Regularly descale the DHW cylinder in line with the actual amount of
limescale using chemical cleaning methods (e.g. with a suitable
descaling agent based on citric acid).
▶ Clean out the DHW cylinder interior with a water jet
( Fig. 21, page 65).
▶ Remove the residues with a wet & dry vacuum cleaner with plastic
suction hose.
▶ Close the inspection aperture with a new gasket
( Fig. 24, page 66).
▶ Re-commission the DHW cylinder ( chapter 6, page 38).
SU120.5 | SU160.5 | SU200.5 | SU200.5 E – 6 720 819 283 (2016/04)
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
9.2.3

Checking the magnesium anode

The DHW warranty is void if the magnesium anode is not
correctly maintained.
The magnesium anode is a sacrificial anode that is consumed when the
DHW cylinder is in use.
We recommend that the protection current is measured annually using
an anode tester ( Fig. 19, page 65). The anode tester is available as
an accessory.
Never bring the magnesium anode surface into contact
with oil or grease.
▶ Keep everything clean.
▶ Shut off the cold water inlet.
▶ Depressurize the DHW cylinder ( Fig. 15, page 64).
▶ Install and test the magnesium anode ( Fig. 20 to Fig. 24,
page 65).
▶ Replace the magnesium anode if its diameter has been reduced to
below 15 mm.
▶ Check the transition resistance across the earth connection and the
magnesium anode.
Maintenance 9
39