A "qualified" engineer has fitted a replacement Grundfos pump (UPS 15-50) to our oil-fired system. I've just noticed the flow direction arrow is pointing upwards, when the old one pointed downwards. The pump seems to lie in the the cold return, so the old arrangement made sense. However, I note that Grundfos do not recommend pumping downwards because of the risk of air locks. Has he done the right thing by reversing it or is this asking for trouble?