Grundfos recommends pump installation as per instructions below:
Pump Mounting: For Indoor Use
Arrows on the side or bottom of the pump indicate direction of flow through the pump.
Grundfos circulators can be installed in both vertical and horizontal lines.
The pump must be installed with the motor shaft positioned horizontally.
Under no circumstances should the pump be installed with the shaft vertical
or where the shaft falls below the horizontal plane.

It is recommend that isolation valves be installed on each side of the pump.
If possible, do not install elbows, tees, and similar fittings just before or after the pump.
Provide support for the pump to reduce thermal and mechanical stress on the pump.

Taco recommends pump installation as per instructions as below:
Circulator must be mounted with the motor in the horizontal position.
See diagrams below for acceptable motor mounting orientations.

Electrical box must be located above or on side of motor housing.