Installing A Safety Valve (On-Site); Installing The Dhw Temperature Sensor; Immersion Heater (Accessory); Commissioning - Buderus SU300.5 serie Installations- Und Wartungsanleitung Für Den Fachhandwerker

6

Commissioning

5.2.2

Installing a safety valve (on-site)

▶ Install a type-tested safety valve that is approved for potable water
( DN 20) in the cold water supply ( Fig. 10, page 55).
▶ Observe the safety valve installation instructions.
▶ 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 ( Table 4, page 36).
▶ 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:
▶ Install a pressure reducer upstream ( Fig. 10, page 55).
Mains pressure Safety valve
(static pressure) response pressure
 6 bar
< 4.8 bar
5 bar 6 bar
 8 bar
5 bar
 8 bar
6 bar
7.8 bar 10 bar
Table 7 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 53).
▶ Install the DHW temperature sensor ( Fig. 11, page 56). Ensure
that the sensor area has contact with the sensor well surface area
over its full length.
5.4

Immersion heater (accessory)

▶ Install the immersion heater in accordance with the separate
installation instructions.
▶ When installation of the cylinder is complete, inspect the earth
conductor (including metal connection fittings).
6 Commissioning
NOTICE: Risk of system damage through excessive
pressure!
Excessive pressure can result in tension cracks in the
enamel coating.
▶ Never close the blow-off line of the safety valve.
▶ 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.
▶ Flush the DHW cylinder and pipework thoroughly prior to
commissioning ( Fig. 13, page 56).
38
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
6.2

Instructing users

WARNING: Risk of scalding at the hot water draw-off
points!
Depending on the system and operating conditions
(thermal disinfection) there is a risk of scalding at the
DHW draw-off points in DHW mode.
Installation of a thermal mixer is prescribed when setting
a DHW temperature via 60 °C.
▶ Advise users that they should draw off only mixed
water.
▶ Explain the operation and handling of the heating system and
cylinder, making a particular point of safety-relevant features.
▶ Explain the function and how to check the pressure relief valve.
▶ Hand all enclosed documents over to the user.
▶ Recommendation for the operator: Conclude a maintenance and
inspection contract with an approved contractor. Have the cylinder
serviced and inspected annually at the specified maintenance
intervals ( Table 8, page 39).
Highlight the following for the user:
▶ Setting the DHW temperature.
– Water may be discharged from the pressure relief valve when
heating-up.
– Always keep discharge pipe for pressure-relief valve open.
– Comply with maintenance intervals ( Table 8, page 39).
– Where there is a risk of frost and when the operator is briefly
away: Keep the heating system in operation and set the lowest
possible DHW temperature.
7

Shutting down

▶ If an immersion heater has been fitted (accessory), isolate the DHW
cylinder from the power supply ( Fig. 15, page 57).
▶ Switch off the temperature controller at the control unit.
WARNING: Scalding from hot water!
▶ Let the DHW cylinder cool down sufficiently.
▶ Drain the DHW cylinder ( Fig. 15 and 16, page 57).
▶ Decommission all assemblies and accessories of the heating system
as specified in the manufacturer's technical documentation.
▶ Close the shut-off valves ( Fig. 17, page 57).
▶ Depressurize the indirect coils.
▶ Drain and blow out the indirect coils ( Fig. 18, page 57).
▶ To prevent corrosion, dry out the interior and keep the inspection
aperture covers open.
SU300.5 | SU400.5 – 6 720 819 326 (2019/12)