Startup; Before Start-Up; Venting The Pump; Venting Of Heating Systems - Grundfos ALPHA1 Series Installation And Operating Instructions Manual

10. Startup

10.1 Before start-up

Do not start the pump until the system has been filled with liquid
and vented. The required minimum inlet pressure must be
available at the pump inlet. See sections 4. Applications and
13. Technical data and installation dimensions.

10.2 Venting the pump

Fig. 12 Venting the pump
The pump is self-venting. It need not be vented before start-up.
Air in the pump may cause noise. This noise will cease after a few
minutes running.
Quick venting of the pump can be obtained by setting the pump to
speed III for a short period, depending on system size and
design.
When the pump has been vented, i.e. when the noise has
ceased, set the pump according to the recommendations.
See section 8. Setting the pump.
Caution
The pump must not run dry.
The system cannot be vented through the pump. See section

10.3 Venting of heating systems.

20
1
III
II I POWER
1
III
I
= 10 Min.
10.3 Venting of heating systems
1
2
III
II I POWER
Fig. 13 Venting of heating systems
The heating system can be vented in the following ways:
• via an air escape valve installed above the pump (A)
• via a pump housing with air separator (B).
In heating systems that often contain much air, we recommend
the installation of pumps with pump housing with air separator,
i.e. ALPHA1 pumps, type ALPHA1 XX-XX A.
When the heating system has been filled with liquid, follow this
procedure:
1. Open the air escape valve.
2. Set the pump to speed III.
3. Let the pump run for a short period, depending on system size
and design.
4. When the system has been vented, i.e. when the possible
noise has ceased, set the pump according to the
recommendations. See section 8. Setting the pump.
Repeat the procedure, if necessary.
Caution
The pump must not run dry.
A
B
3
III
I
= 10 Min.