Grundfos UPE Serie Instrucciones De Instalación Y Funcionamiento página 14

9. Start-up
Do not start the pump until the system has been filled with liquid and vented.
Furthermore, the required minimum inlet pressure must be available at the
pump inlet. See the general installation and operating instructions.
Note
The system cannot be vented through the pump.
9.1 Venting the pump
Vent the pump before start-up. See figure below.
Warning
When the air vent screw is loosened, scalding hot liquid
under high pressure may escape. Take care that escaping
liquid does not cause personal injury or damage to
components.
Due to air remaining in the pump, the pump may be noisy when first switched
on. This noise should cease after a few minutes of operation.
After start-up, set the desired operating mode and head.
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Air vent screw
Venting the pump