Delta 3 classic as a UPS

I am using my Delta 3 Classic as a UPS to power my basement sump pump. I have the AC power timeout set to 'never' and everything else is in the factory default. The system appears to work as I hoped. When main input power is present, it passes through to power the pump and when the main input power is off ( power outage) the pump is powered by the inverter. Is there anything else I should consider?