I have the newer United Spas control Pack, 240 Volt, 50 AMP. Tub heats and works okay for a few days, then fails to heat. Examination showed that one of the lead wires to element fried and burnt in half. I reconnected, all was well for two days, then same thing happened. I reconnected again, and tub is heating successfully as I write. But obviously, something is causing these wires to grossly overheat. The heating element is brand new and seemingly functioning well (tub is heating at 6 degrees/hour). Any thoughts as to what might be causing wires to overheat? Also what is typical setting for flow sensor on heater housing? Thank you

Typically it's caused by a poor wiring connection (loose terminal connection, corrosion, etc,) , which causes resistance and too much amp draw through the wire, causing it to over heat and burn through. Once that happens, much of the wire will be damaged, causing it to be restrictive to electric flow, causing too much amp draw through the wire, causing it to over heat and burn through. Most people don't cut out any where near enough of the old damaged wire when repairing.

Oh, just because the element is new, doesn't guarantee it's not the problem either

Thanks for your quick response. Do you have any thoughts why the original wire burnt up in the first place? It had only been in service two days. I did replace the wire and so far have 36 hours and counting-holding my breath. Thanks again.