Wolf BWL-1 S Installation And Operating Instructions Manual page 32

DHW cylinders
Buffer cylinder
Recommended buffer
cylinder sizing for the
BWL-1S(B)
Recommended sizing for
diaphragm expansion vessel
(DEV)
Approximate pipework
calculation for heating water
flow rates and Cu pipes without
bends (observe residual head of
pump).
Air heat pump Nominal water flow rate Minimum cross-section,
BWL-1S(B)-07
BWL-1S(B)-10 400V
BWL-1S(B)-14 400V
BWL-1S(B)-10 230 V
BWL-1S(B)-14 230 V
32
20. Connecting the heating / cooling
circuit and the DHW circuit
- The DHW cylinder must be equipped with an internal indirect coil suitable for the
heating output of the heat pump.
- The internal indirect coil should have a surface area of at least 0.25m² per kW of
heating output.
- The pipework must be sufficiently large (> DN 25).
Since variable flow rates can arise on the heat draw-off side depending on the load,
the minimum flow rate must be ensured to enable fault-free heat pump operation.
This is usually achieved by installing a separating buffer cylinder or a low loss header.
A buffer cylinder is essential for all systems with radiators, individual room
temperature control (thermostatic valves), multiple heat generators or heating
circuits.
For air/water heat pumps with output-dependent control in connection with 100 %
underfloor heating, there is no need to use a buffer cylinder, provided the following
condition is met:
1 (or more) lines of the heating system (e.g. bathroom) is permanently and fully open
(requires the written consent of the operator). For this, the minimum flow rate must be
verified by means of a pressure drop calculation.
If necessary, one (or more) heated heating circuits(s) can be specifically opened fully
via output A1 during defrost mode.
The valve opening time must be < 20 sec.
Size calculation for air/water heat pumps:
Approx. 10 litres/kW heating output (for A2/W35)
Air/water
heat pump
Buffer cylinder
A buffer cylinder for optimising compressor runtime is not required, thanks to
the inverter technology; therefore smaller buffer cylinders are sufficient
Expansion vessel
size
25 litres
35 litres
50 litres
80 litres
100 litres
140 litres
200 litres
In order to ensure that the heat pump operates reliably and efficiently, it is essential
that the flow rates specified in the technical data for the heating circuit can be
guaranteed. The following table lists the required minimum cross-sections for the
pipework on the heating circuit side. On systems with a separating cylinder or low
loss header, these cross-sections must, as a minimum, be observed up to the
separating cylinder (e.g. incl. the BSP/BSH) or the low loss header.
heating circuit pipework
19.7 l/min Pipe Ø 35x1.5 /
28.8 l/min Pipe Ø 35x1.5
34.1 l/min Pipe Ø 35x1.5
31,8 l/min Pipe Ø 35x1.5
40,4 l/min Pipe Ø 35x1.5
BWL-1S(B)-07 BWL-1S(B)-10
SPU-1-200 SPU-1-200
Water content
heating system
235 litres
320 litres
470 litres
750 litres
850 litres
1210 litres
1600 litres
Pressure loss
per metre
0.75 mbar/m /
28x1.5 2.4 mbar/m
1.5 mbar/m
2.0 mbar/m
1,7 mbar/m
2,6 mbar/m
BWL-1S(B)-14
SPU-1-200
.
Expansion vessel
pre-charge pressure
1.5 bar
1.5 bar
1.5 bar
1.5 bar
1.5 bar
1.5 bar
1.5 bar
Flow velocity
0.41 m/s /
0.67 m/s
0.60 m/s
0.71 m/s
0,66 m/s
0,84 m/s
3064298_201507