I have a 40 year old toilet that drains out he the back. It is leaking from the waste line and I suspect that the wax ring has failed. The other side of the wall it is on is a pipe chase containg supply and drain lines as well as the 2" hot water heating supply lines for my condo and the two below me. I suspect that the wax ring failure is due to the excessive heat inside this pipe chase. I am having trouble finding information on a non wax seal that is suitable for a rear draing toilet. I need to do this repair this weekend and was looking for some advice. I have thought about a felt gasket and possibly some kind of uerthane seal, but because rear training toilets are not very common, I am having trouble finding information on what will work best.