I’m looking to get my spa back up and running as we are trying to sell our house. The heating element has gone and need a cheap replacement. I found an open box No Fault 4kw element for about $300 less than the current heater exact replacement which is a 6kw No Fault. My question is, can downgrading the element still work? Will it simply use more power to sustain temp? Take longer to get to temp? I’m asking about a Tiger River 2002 Siberian. Thanks!