S&P PWW Notice D'installation page 9

Check valve
The check valve allows circulation by gravity of the hot water (opening pressure 20 mbar
approx.) when the pump is off.
Operating position: check valve closed, passage only in flow direction.
When putting the system into operation and during maintenance work (filling and flushing), the
check valve must be opened.
Isolation function inactive: Check valve opened, flow is possible in both directions.
During heating operation, the check valve must be set to operating position.
The "PWW" must be equipped with a differential pressure relief valve (order separately). This
valve must always be installed in the return flow pipe. The cap with extension must be removed
to open the bypass.
If needed, the other cap (without extension) must be assembled on the other side.
Differential pressure
Differential pressure
relief insert
relief device
Plug with extension
The differential pressure relief accessory is preadjusted at an opening pressure of 200 mbar.
Another opening pressure of 50 to 400 mbar can be adjusted on the flywheel - marked on the
scale.
Flow chart bypass DN 25
(differential pressure relief device)
The PWW is additionally equipped with a bypass with manual presetting at the three-way mixing
valve. When leaving the factory, the bypass is closed. (Slit of the bypass stem turned by 90°
towards the bypass channel, position "off", see illustration.)
By turning the bypass stem by 90°, i.e. slit running parallel to the bypass
channel, position "on", the maximum flow rate can be reached.
Kv values:
II) and bypass "stem" completely opened
Mixing valve (I
Kv = 4.7
Mixing valve closed (III
Mixing valve completely opened (I
Kv = 4.3
Plug
Plug Plug
Supply on right hand side
ä
Flow rate V [m h]
II), bypass opened Kv = 2.6
II), bypass closed
Differential pressure
Differential pressure
relief device
relief insert
Supply on left hand side
Plug with extension
Flow chart bypass DN 32
(differential pressure relief device)
Flow rate V [m h]
ä
Safety
screw