We have a 5 Year Old Power Vent 98 Gallon Gas Heater Rheem Pro G98 75U RH that has been having the same issues for years. We keep getting moisture outside where the drain pipe goes. The Plumber has replaced the T & P valve twice already with the factory part. We also have an issue with temperature. At the "Normal Setting" the water is way too hot and can burn at the faucet or shower, which also causes even more moisture outside from all that heat. If set at one notch below normal, the water is lukewarm at best. The plumber added an expansion tank a few years ago and that did nothing. Instead of me buying another T & P valve I was going to ask Rheem for one along with a gas control unit for the temperature, but was thinking of asking for a brand new heater since it has an 8 year warranty and we are not sure these parts would solve the problems. Not sure what to do ? My Plumber is suggesting a commercial T & P valve instead of the small factory size.