From what I have seen, only commercial establishments such as hotels and such use one of these, but...that's exactly what I just took out from under a Beachport spa. The tub came with the house, built-in inside. We enjoy having the option of using the Hot Springs Sovereign outside, or the big ol' Beachcraft inside. Unfortunately, the previous owners made their own thermowell when adding a top side temp control (Spa-Temp ST-130), it sprang a leak, the heater ran dry (no clue why the the flow switch didn't shut the pump down, apparently it wasn't working!) and needless to say, after pulling the element and testing with a multi-meter, the element is fried. So...what I need is the replacement for Heater Control Box with Element: Part No. C-2500-3-KW12. This was part of a Hayward Max-Pak C-500-15MP2H12 (11.5KW) 1 1/2 horsepower system. Everything else is working fine. I pulled the heat sensing bulb from the thermowell, and have unhooked the top mount control from the system. It's of no use to me, when we find the temp we like, it stays there anyway. We had great luck with the larger heater, as we do have parties and the inside hottub stays open for long periods of time. This seems to be the place to get the best help with parts needs, so let me know if you have ideas, or if this is just too old to replace?