Based upon the pictures Brandon posted, the valve Pete pictured sure looks like a pressure valve only. It seems recommending the valve be replaced with a TPR valve would make good sense.

As for where the discharge line for the valve should exhaust, it will vary by region. Being as Pete is up in New Hampshire, exhausting a line to the exterior would make it susceptible to freeze-ups. Around here in Pennsylvania, these valves exhaust indoors and onto the floor. I've never understood how having these valves exhaust into a drain line or to the exterior is supposed to help the homeowner determine if there is a problem with the unit. If you see water beneath the valve on the floor, you know it may need repairs. If you can't see anything, a problem stands to go unknown and uncorrected for a longer period of time.