I'm about to fit a Salamander shower pump from their CT range. The installation instructions say that "cold water supplies to the pump must be taken from the opposite side of the cold water storage cistern to the cold water mains inlet". I've checked with Salamander and they say if the outlet from the cold water roof tank feeding the pump is directly below the float valve inlet then there is a risk of entraining air in the supply to the pump and damage to the pump is possible. They say I should move the inlet so it is at least 90 degrees round the tank away from the outlet, otherwise the warranty will be invalid.
Is this normal? Has anyone else done this? Surely the standard arrangement of roof tanks is for the outlets to be directly below the inlets? I can't believe there's an army of plumbers out there moving the inlets to roof tanks to comply with this. Is it just a get-out for Salamander to avoid honoring warranties, or is it actually a real issue? I've looked at Grundfos and Stuart Turner shower pump instructions and they do not mention this.