Thanks Ollie, yes it would've been better to use one of those, but unfortunately I was ill advised and now have to use what I have. If there's a simple way to wire up the existing unit to achieve thermal overload protection then that's the way to go.... don't really need the start/stop options, there's a simple reset button on the overload unit to press in the unlikely event of motor overload. The pump is serving a single property of just one occupant so unlikely to be any issues