The engine trips are due to air trapped in the piping, and the air would cause the pump to see low pressure which in turn tripped the unit. We’ve added a number bleeder valves at various points to attempt to get all the air out of the system. It helps but still doesn’t alleviate the problem. We have gone in and extended the timer for the pump to establish pressure to get past the start-up problem. Still takes quite a while to get all the air burped out of the system.