Viessmann D2RA, Installation Instructions For Contractors

Page: 42 / 164

42
Filling the process circuit
Note
A separate expansion vessel is installed in the appli-
ance for the process circuit.
Before filling the process circuit:
■ Check the pre-charge pressure of the internal expan-
sion vessel (see page 57).
Charge pressure: 1.7
±
0.25
bar (170 ±
25
kPa).
■ Thoroughly flush the process circuit.
The Viessmann filling station can be used for flush-
ing.
C
B
A
D
E
F
H
G
F
H
G
Fig. 29
A
Pressure gauge
B
Air vent valve
C
Quick-action air vent valve
D
Drain & fill valves in the "filling" position:
F
Upper drain & fill valve open
G Centre shut-off valve closed
H Lower drain & fill valve open
E
Drain & fill valves in the "operating" position:
F
Upper drain & fill valve closed
G
Centre shut-off valve open
H
Lower drain & fill valve closed
0 1. Close the gas shut-off valve and switch the control
unit ON.
0 2. Check whether the air vent screw in quick-action
air vent valve
C
of the process circuit is open.
0 3. Connect the fill hose to upper drain & fill valve
F
.
0 4. Connect one end of the drain hose to lower drain
& fill valve
H and the other end to a drain outlet.
0 5. Set drain & fill valves to "filling" position
D
.
0 6. Open the water tap.
0 7. Activate the filling and venting program (see next
chapter or confirm with
OK when running the com-
missioning assistant).
0 8. When the filling and venting program is finished,
close
lower drain & fill valve
H
.
0 9. As soon as the required operating pressure has
built up at pressure gauge
A
, close upper drain
& fill valve
F
and the water tap.
Operating pressure: 2.8 to 3.0 bar (0.28 to
0.3 MPa).
Note
The safety valve opens at an operating pressure
of 4.0 bar (0.4 MPa).
Take into account the increased volume and pres-
sure caused by the heating up of the fill water dur-
ing operation.
10. Open centre shut-off valve
G
. Drain & fill valves
are in position
E
, "operation".
11. Close the air vent screw at quick-action air vent
valve C .
12. Open the gas shut-off valve.
Note
During the early weeks of operation, air dissolved in
the fill water can escape, making it necessary to top up
the system.
Do not flush the process circuit when topping up, as
otherwise air dissolved in the water would be intro-
duced again.
1. Vent the fill hose and connect it to upper drain & fill
valve F .
2. Connect the vent hose to air vent valve
B
and open
the air vent valve.
3. Release accumulated air (but not water). Close air
vent valve
B
again.
4. Only open upper drain & fill valve
F
("filling" posi-
tion
D
) and top up the process circuit.
5. As soon as the operating pressure has built up at
pressure gauge
A
, close upper drain & fill valve
F
and the water tap.
Commissioning, inspection, maintenance
Filling and venting the process circuit
(cont.)
5678 044 GB