I just replaced the old water heater with a new bradford white gas heater. Everything went smooth until I fired it up and about 15 minutes later the relief valve started dripping. I had the heat set to 'hot' as a starting point per the manual. I searched this site and found that a few others had issues like this, so I have some direction. Now I need to isolate what is causing it, temp or pressure. There is a PRV in the line from the city but I don't think there is an expansion tank, I'll have to look closer to see if its hidden somewhere. I also need to get a pressure gauge to see what is happening.