It could work. However, everything I read suggests a wax ring isn't as good as the rubber gasket usually used in RVs. The thinking is the wax softens with heat and deform under vibration. Not sure I buy the argument but all the RV mfg use the rubber gasket.
Ours, as put together, had no seal between the hydroseat and the "flange". This is certainly not right. It's also not stable as is. The wax seal would add some rigidity but I think likely not enough. I think the hydroseat may be too high even with no wax seal. The toilet is still tippy when fully tightened. It's either not sucking down to the floor or the hydroseat is flexing.
But it may be the best and certainly be the easiest solution. It's encouraging to hear they work well in residential applications.
Originally Posted by Kevin A
I have used those replacement flanges for toilet in old houses. I usually put a wax ring around the opening in the floor, put the DANCO flange over it and screw the flange to the floor. The new toilet then sits in the new flange with the rubber gasket acting as the seal for the toilet out-flow. I think that would work for you based on your picture. If the wax ring sits too high, I've shaved them done to fit, too.