Tpr valve location on rheem 7130s - Rheem Water Heater Pressure Relief Valve

SOURCE: Water Heaer Problems

Although rare the pipes may both me hotter near the heater and the cold water line will get colder the farther back you go from the heater. Now I would do yourself a favor and hire another plumber to do the work on your water heater because from what your telling me these guys don't know anything about water heaters and I suspect they may have bumped your TPR valve (although if you ask them I'm almost positive they'll deny it). Here's what happens. From not be being used all the time the TPR valve gets buildup in it from your water lines, and as soon as the lever is pushed the TPR valve will constantly leak water until it is replaced. I would try replacing that first. To replace it simply unscrews with a wrench, just be sure to turn your water heater off and drain it halfway before replacing. That is the least expensive option. Next I would try putting in an Amtrol Expansion tank. Your local home store can get you the right one. It expands when there is excess pressure in the line. A plumber would have to install this and if you already have one make sure it is working properly. These are the only two things that would make a TPR valve leak. So while the two are not linked, I still don't think it is a coincidence.