en
6
7
Flow rate measurement
The VFS Grundfos Direct Sensor
TM
is used for meas-
uring the flow rate and the temperature. In order to
ensure faultless operation of the sensor, the system
has to be flushed and must be free of dirt particles.
orifice in the measurement
head
8
Air separator
WARNING!
Scald danger!
During venting, the air discharged can
reach temperatures of more than
100 °C.
Î
In order to avoid scalding,
pay attention to the system
temperatures!
The air separator is used for venting the water / glycol
mixture in the solar circuit. The air separated from the
heat transfer fluid gathers in the air scoop and can be
discharged manually at the air vent valve.
Î
Open the air vent valve and collect the discharged
fluid in a suitable container.
Î
Check the system pressure after bleeding and, if
necessary, increase it to the specified operating
pressure.
9
Maintenance
In the case of maintenance (such as a replacement of
the pump) proceed as follows:
Î
Close the ball valve (4).
Î
Turn the slot of the flowmeter spindle by 90°
anti-clockwise (see figure below).
The heat transfer fluid can now be drained from the
pump.
Î
Open the drain valve (3).
If necessary, open the union nut at the pressure side.
Î
Now dismount the pump.
10 Safety devices
The pump station is equipped with a diaphragm safety
valve which corresponds to the relevant directives
and regulations. For installation and operation, please
pay attention to the following advice:
• The safety valve has to be easily accessible. The ef-
ficiency of the valve must not be influenced or disa-
bled by barriers!
• The strainer or other restriction devices must not
be mounted between collector (-field) and safety
valve!
• The diameter of the discharge pipe must cor-
respond to the diameter of the valve outlet; the
maximum length must not exceed 2 m; more than
2 bends are inadmissible. When these values are
exceeded, you have to install a discharge pipe with
larger dimensions. Do not use more than 3 bends
and pipes longer than 4 m!
• If the discharge pipe leads into a drain pipe with a
funnel, the diameter of the drain pipe has to be at
least twice as large as the valve inlet. The opening of
the discharge pipe must be inclined downwards. It
must be routed such that the opening can be seen
but does not present any risk to a person standing
or passing by.
• We recommend placing a container below the dis-
charge pipe. If the safety valve opens, the fluid will
be collected and can be refilled into the system
when the pressure is too low.
