Looking into a new heater. Old one is very, very old. Still fires up but needs regular attention (relight pilot frequently, replaced thermocouple twice in two years). The heater itself looks good, but with the front panel removed I can see that the bottom of the unit has nearly rusted through. It sits directly on a concrete pad. My thought is that when we replace I'll put the new one on an Ultralight mounting pad (the ones that A/C units sit on) so it will elevate the unit by a few inches. I checked a couple of pool heater manuals online and they say it's an acceptable method but I'm wondering if anyone's done it and noticed any difference?