Wolf BWL-1 S - Page 32

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20. Connecting the heating / cooling
circuit and the DHW circuit
Size calculation for air/water heat pumps:
Approx. 10 litres/kW heating output (for A2/W35)
Air/water
heat pump
BWL-1S(B)-07 BWL-1S(B)-10 BWL-1S(B)-14
Buffer cylinder SPU-1-200 SPU-1-200 SPU-1-200
Recommended buffer
cylinder sizing for the
BWL-1S(B)
A buffer cylinder for optimising compressor runtime is not required, thanks to
theinvertertechnology;thereforesmallerbuffercylindersaresufcient
.
Recommended sizing for
diaphragm expansion vessel
(DEV)
Expansion vessel
size
Water content
heating system
Expansion vessel
pre-charge pressure
25 litres 235 litres 1.5 bar
35 litres 320 litres 1.5 bar
50 litres 470 litres 1.5 bar
80 litres 750 litres 1.5 bar
100 litres 850 litres 1.5 bar
140 litres 1210 litres 1.5 bar
200 litres 1600 litres 1.5 bar
Sincevariableowratescanariseontheheatdraw-offsidedependingontheload,
theminimumow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 %
underoor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owratemustbe
veriedbymeansofapressuredropcalculation.
Ifnecessary,one(ormore)heatedheatingcircuits(s)canbespecicallyopenedfully
via output A1 during defrost mode.
The valve opening time must be < 20 sec.
Buffer cylinder
Inordertoensurethattheheatpumpoperatesreliablyandefciently,itisessential
thattheowratesspecied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.
Approximate pipework
calculation for heating water
owratesandCupipeswithout
bends (observe residual head of
pump).
Air heat pump Nominalwaterowrate Minimum cross-section,
heating circuit pipework
Pressure loss
per metre
Flow velocity
BWL-1S(B)-07 19.7 l/min Pipe Ø 35x1.5 /
28x1.5
0.75 mbar/m /
2.4 mbar/m
0.41 m/s /
0.67 m/s
BWL-1S(B)-10 400V 28.8 l/min Pipe Ø 35x1.5 1.5 mbar/m 0.60 m/s
BWL-1S(B)-14 400V 34.1 l/min Pipe Ø 35x1.5 2.0 mbar/m 0.71 m/s
BWL-1S(B)-10 230 V 31,8 l/min Pipe Ø 35x1.5 1,7 mbar/m 0,66 m/s
BWL-1S(B)-14 230 V 40,4 l/min Pipe Ø 35x1.5 2,6 mbar/m 0,84 m/s
- 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sufcientlylarge(>DN25).
DHW cylinders