Connecting The Dhw Cylinder On The Water Side; Installing A Safety Valve (On-Site); Installing The Dhw Temperature Sensor; Iimmersion Heater (Accessory, Only For Su200/5E) - Buderus SU120/5 Installation And Maintenance Instructions Manual

6

Commissioning

5.2.1 Connecting the DHW cylinder on the water side

System example with all recommended valves and stopcocks
( Fig. 11, page 102).
B Use installation material that is heat-resistant to 160 °C (320 °F).
B Never use open vented expansion vessels.
B Use metal connection fittings in DHW heating systems with plastic
lines.
B Size the drain line in accordance with the connection.
B To facilitate blow-down, never install bends in the drain line.
B Keep primary lines as short as possible and insulate them.
B If using a non-return valve in the cold water supply: Install a safety
valve between the non-return valve and the cold water inlet.
B Install a pressure reducer if the static system pressure is in excess of
5 bar.
B Seal all superfluous connections.

5.2.2 Installing a safety valve (on-site)

B Install a type-tested safety valve that is approved for potable water
(≥ DN 20) in the cold water supply (
B Observe the safety valve installation instructions.
B Terminate the discharge pipe where it will be easily visible in the frost-
protected area above a drain.
– The discharge pipe must be at least equal to the outlet cross-
section of the safety valve.
– The discharge pipe must be able to discharge at least the flow rate
that is feasible at the cold water inlet (
B Attach a notice with the following text to the safety valve: "Never close
the discharge pipe. During heating, water may be discharged for
operational reasons."
If the static system pressure exceeds 80 % of the safety valve response
pressure:
B Install a pressure reducer upstream (
Mains pressure Safety valve
(static pressure) response pressure
< 4.8 bar ≥ 6 bar
5 bar 6 bar
5 bar ≥ 8 bar
6 bar ≥ 8 bar
7.8 bar 10 bar
Table 6 Selection of a suitable pressure reducer
5.3

Installing the DHW temperature sensor

Fit one DHW temperature sensor respectively at test port [7] (for the
solar thermal system) and [3] (for the heat source) for capturing and
monitoring the DHW temperature at the DHW cylinder
( Fig. 3, page 99).
B Install the DHW temperature sensor (
that the sensor area has contact with the sensor well surface area over
its full length.
5.4

IImmersion heater (accessory, only for SU200/5E)

B Install the immersion heater in accordance with the separate
installation instructions.
B When installation of the cylinder is complete, inspect the earth
conductor (including metal connection fittings).
24
Fig. 11, page 102).
Table 4, page 22).
Fig. 11, page 102).
Pressure reducer
in the EU outside the EU
Not required
max. 4.8 bar
Not required
max. 5.0 bar Not required
max. 5.0 bar Not required
Fig. 12, page 102). Ensure
6 Commissioning
NOTICE: Risk of system damage through excessive
pressure!
Excessive pressure can result in tension cracks in the
enamel coating.
B Never close the blow-off line of the safety valve.
B Commission all assemblies and accessories as specified in the
manufacturer's technical documentation.
6.1

Commissioning the DHW cylinder

Check the DHW cylinder for leaks using potable water
only.
On the DHW side, the test pressure must not exceed 10 bar (150 psi)
positive pressure.
B Flush the DHW cylinder and pipework thoroughly prior to
commissioning ( Fig. 14, page 103).
6.2

Instructing users

WARNING: Risk of scalding at the hot water draw-off
points!
There is a risk of scalding at the hot water draw-off
points if the DHW temperature is set above 60 °C and
during thermal disinfection.
B Advise users that they should only draw off mixed
water.
B Explain the operation and handling of the heating system and DHW
cylinder, making a particular point of safety-relevant features.
B Explain the function and checking of the safety valve.
B Hand all enclosed documents over to the user.
B User recommendation: Arrange an inspection/maintenance
contract with an approved heating contractor. Have the DHW cylinder
inspected and, if required, serviced annually in accordance with the
service intervals stated ( Table 7, page 25).
B Highlight the following for the user:
– Water may be discharged from the safety valve during heat-up.
– The safety valve discharge pipe must always be kept open.
– Service intervals must be observed (
– Recommendation in the case where there is a risk of frost and
when the user is briefly away: Keep the DHW in operation and
select the lowest possible DHW temperature.
7

Shutting down

B If an immersion heater has been fitted (accessory), isolate the DHW
cylinder from the power supply .
B Switch off the temperature controller at the control unit.
WARNING: Scalding from hot water!
B Let the DHW cylinder cool down sufficiently.
B Drain the DHW cylinder ( Fig. 16 and 17, page 103).
B Decommission all assemblies and accessories of the heating system
as specified in the manufacturer's technical documentation.
B Close the shut-off valves (
SU120/5, SU160/5, SU200/5, SU200/5E – 6 720 801 756 (2012/06)
Table 7, page 25).
Fig. 18, page 104).